1989 5.8 fuel pressure question

[mikefamig]

I've searched around the net and have seen this question asked countless times but can not come up with a definitive answer.

I have the common cold start problem where I have to spin the engine long, the engine starts rough and then smooths out quickly and I have done some testing with a fuel pressure gauge. The pump makes 40psi KOEO. The regulator limits the pressure to ~32psi idling. When I turn the engine off the pressure holds up for a long time. I think that it was a half hour before it dropped at all. The pressure goes to zero overnight.

Now I have seen claims that it is normal for pressure to drop to 15 - 20 psi 15 minutes after stopping engine. I have also read that it is normal if the pressure is zero after sitting overnight and some that claim that it should hold pressure overnight. I plan to do further testing by clamping off the feed and return fuel lines overnight both together and individually but in the meantime.....

My first question:

1 Is it normal for the fuel pressure to drop to zero after sitting for 12 hours or so?

and

2 Where are the check valves in the fuel system?I have seen claims that they are in the fuel tank pump and in the high pressure pump and in the regulator and in the reservoir. The best that I can tell so far is that there are two in the single function reservoir, one in each direction, and I can't seem to veriy that for sure.


EDIT
I am aware that the pressure escapes through three possible routes, the supply line, the return line and the injectors. There is no black smoke when the engine starts and the problem only occurs after the car has sit for an hour or more.

 

[Motech]

I have never seen any published Ford specs on fuel pressure retention beyond a couple minutes of rest time.

Let's say a single-tank, dual-pump system like yours in excellent condition delivers 34 psi regulated idle and 43 psi idle w/ regulator vacuum disconnected. When idling at regulated 34 psi, we can expect a pressure rise on shut-off about midway, say 38-39 psi that will still be holding when we come back five minutes later. An hour? 5-10 psi drop would not concern me, and overnight I would not be concerned if we found pressure had dropped to under 10 psi.

What would concern me is any immediate loss after engine shut-off.

Even moreso is ability to achieve full operating pressure with key-on prime the next morning. If you come out and see 5-15 psi after overnight soak, I would expect pressure to jump to full unregulated 43 psi in the first KOEO pump prime. If it pressure is zero, and it takes two or more KOEO prime events to achieve unregulated pressure, you have some delivery issues that need to be looked into.

Not counting injectors, you're going to have three anti-return "check valves" to consider: Regulator, in-tank lift pump and frame-mounted main pump set up like this:





The electric fuel pump system consists of two fuel pumps: a low pressure boost pump mounted in the fuel tank, and a high pressure fuel pump mounted on the frame rail. An in-line reservoir is located at the high pressure pump inlet. This design provides for satisfactory fuel pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fill levels.

The low pressure electric fuel pump is used to provide pressurized fuel to the inlet of the high pressure pump and helps prevent noise, hot fuel problems, and prevent dirt and other particulate matter from entering the system. Any water accumulation in the fuel tank can pass through the filter without restriction.




The externally mounted high pressure fuel pump is capable of supplying 80 liters (21.2 gallons) of fuel per hour at a working pressure of 269.0 kPa (39 psi). The pump has an internal pressure relief valve to provide overpressure protection in the event the fuel flow becomes restricted. Overpressure is restricted to 950 kPa (138 psi) and reduced fuel flow will result. The system pressure is controlled by a pressure regulator on the engine.


I have seen in-tank pump failures that stress the pressure pump big-time and cause extended delays in system prime after overnight leak-down, with symptoms just like yours.

These systems require an additional step to determine which pump is leaking down. If your're losing pressure through the pump side (with return line blocked), then both pumps are shot. But if that rear pump is losing it's prime--or worse, not working--it will not show up with the front pump covering it's behind. You'd need to isolate that pump from the mix to know for sure.


STO Connector



STATIC PRESSURE TEST
1.Check for adequate fuel supply.
2.Turn key OFF
3.Install fuel pressure gauge to test port on fuel rail.
4.Install test lead to fuel pump lead of STO test connector.
5.Turn Key On Engine Off (KOEO).
6.Ground test lead to run fuel pump.
7.Check to determine if fuel pressure is within acceptable limits. See: Fuel Pressure > Pressure, Vacuum and Temperature
a. If pressure is low but greater than 3 psi (indicates fuel pump is running but not enough pressure) check for:
^ Plugged fuel filter
^ Kinked fuel line
^ Low voltage to pump (should be without 0.5 volts of battery voltage at connector).
^ Disconnect the fuel return line and note if fuel is being returned during this low pressure condition. If fuel is being returned, replace the fuel pressure regulator. Reconnect the fuel return line.
b. If pressure is less than 3 psi (pump not running) check for:
^ Defective fuse link
^ Inertia switch open
^ Wiring at fuel pump/tank connector loose or open
^ Fuel pump ground connection at chassis loose or defective
^ Improper fuel pump relay operation
If fuel supply and return lines are OK, and electrical supply and ground are OK, and fuel pressure is still low, replace fuel pump.

DYNAMIC PRESSURE TEST
1. Disconnect and plug the vacuum line to the pressure regulator.
2. Start engine and run at idle. Check to determine if fuel pressure is within acceptable limits. See: Fuel Pressure > Pressure, Vacuum and Temperature
a. If pressure is low check for:
^ Plugged fuel filter
^ Restricted fuel line
^ Low voltage to pump (should be within 0.5 volts of battery voltage at connector).
3. Reconnect the vacuum line to the regulator.
If fuel supply and return lines are OK, and electrical supply and ground is OK, and fuel pressure is still low, replace fuel pump.

LEAKAGE TEST
1.Momentarily activate fuel pump by grounding test lead. Raise pressure to approximate operating pressure.
2.Remove ground from test lead and note pressure on gauge. Pressure should remain within 2 psi for 3 minutes after lead is ungrounded.
a. If pressure is not maintained check for leaking fuel
^ Lines
^ Connectors
^ Injectors
b. Disconnect fuel return line and plug engine side. Momentarily activate fuel pump by grounding test lead. Raise pressure to approximate operating pressure. If pressure holds replace regulator and retest. Reconnect the fuel return line.
If pressure is not maintained replace fuel pump.

For all these fancy Ford steps, it's really easier to just put a gauge directly inline with the in-tank pump output hose underneath the truck at the frame-mount pump input and energize the pump(s). This will measure the in-tank pump pressure only while still maintaining return system forward. Hard to find specs for, and I've only done this a couple times myself back in the nineties, so I couldn't tell you operating spec. Expect to see 8-12 psi though, and no leakdown. If you get nada, there's your main problem.

Also, the reservoir shown above MAY OR MAY NOT contain a cartridge-style filter inside. Only way to know for sure is to spin the reservoir off and check. If none there, no biggie, just replace that reservoir o-ring if it will not reseal. If there is a filter in there, my cake says it's still original, and could be the bane of all evil your system is currently suffering.

Any of these downstream issues will likely cause a volume/flow problem you will see on a pressure gauge up at the fuel rail though. Tape the gauge to your windshield, take a drive and see what happens to pressure under load. If you idle at 34/43 psi, and you nail it, pressure jumps to 43, then trickles down, down, down the longer you're WFO, you got low pump flow or restricted filters.

 

[Motech]

PS:
Be cautious crimping fuel lines off.

1. Most of them are nylon and can crack if crimped, at best distort
2. It is next to impossible to crimp a line totally shut unless it's rubber and you are using a very strong, broad-shouldered crimper

 

[mikefamig]

I have never seen any published Ford specs on fuel pressure retention beyond a couple minutes of rest time.

Let's say a single-tank, dual-pump system like yours in excellent condition delivers 34 psi regulated idle and 43 psi idle w/ regulator vacuum disconnected. When idling at regulated 34 psi, we can expect a pressure rise on shut-off about midway, say 38-39 psi that will still be holding when we come back five minutes later. An hour? 5-10 psi drop would not concern me, and overnight I would not be concerned if we found pressure had dropped to under 10 psi.

What would concern me is any immediate loss after engine shut-off.

Even moreso is ability to achieve full operating pressure with key-on prime the next morning. If you come out and see 5-15 psi after overnight soak, I would expect pressure to jump to full unregulated 43 psi in the first KOEO pump prime. If it pressure is zero, and it takes two or more KOEO prime events to achieve unregulated pressure, you have some delivery issues that need to be looked into.

Not counting injectors, you're going to have three anti-return "check valves" to consider: Regulator, in-tank lift pump and frame-mounted main pump set up like this:


View attachment 30391


The electric fuel pump system consists of two fuel pumps: a low pressure boost pump mounted in the fuel tank, and a high pressure fuel pump mounted on the frame rail. An in-line reservoir is located at the high pressure pump inlet. This design provides for satisfactory fuel pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fill levels.

The low pressure electric fuel pump is used to provide pressurized fuel to the inlet of the high pressure pump and helps prevent noise, hot fuel problems, and prevent dirt and other particulate matter from entering the system. Any water accumulation in the fuel tank can pass through the filter without restriction.


View attachment 30392

The externally mounted high pressure fuel pump is capable of supplying 80 liters (21.2 gallons) of fuel per hour at a working pressure of 269.0 kPa (39 psi). The pump has an internal pressure relief valve to provide overpressure protection in the event the fuel flow becomes restricted. Overpressure is restricted to 950 kPa (138 psi) and reduced fuel flow will result. The system pressure is controlled by a pressure regulator on the engine.


I have seen in-tank pump failures that stress the pressure pump big-time and cause extended delays in system prime after overnight leak-down, with symptoms just like yours.

These systems require an additional step to determine which pump is leaking down. If your're losing pressure through the pump side (with return line blocked), then both pumps are shot. But if that rear pump is losing it's prime--or worse, not working--it will not show up with the front pump covering it's behind. You'd need to isolate that pump from the mix to know for sure.


STO Connector
View attachment 30390


STATIC PRESSURE TEST
1.Check for adequate fuel supply.
2.Turn key OFF
3.Install fuel pressure gauge to test port on fuel rail.
4.Install test lead to fuel pump lead of STO test connector.
5.Turn Key On Engine Off (KOEO).
6.Ground test lead to run fuel pump.
7.Check to determine if fuel pressure is within acceptable limits. See: Fuel Pressure > Pressure, Vacuum and Temperature
a. If pressure is low but greater than 3 psi (indicates fuel pump is running but not enough pressure) check for:
^ Plugged fuel filter
^ Kinked fuel line
^ Low voltage to pump (should be without 0.5 volts of battery voltage at connector).
^ Disconnect the fuel return line and note if fuel is being returned during this low pressure condition. If fuel is being returned, replace the fuel pressure regulator. Reconnect the fuel return line.
b. If pressure is less than 3 psi (pump not running) check for:
^ Defective fuse link
^ Inertia switch open
^ Wiring at fuel pump/tank connector loose or open
^ Fuel pump ground connection at chassis loose or defective
^ Improper fuel pump relay operation
If fuel supply and return lines are OK, and electrical supply and ground are OK, and fuel pressure is still low, replace fuel pump.

DYNAMIC PRESSURE TEST
1. Disconnect and plug the vacuum line to the pressure regulator.
2. Start engine and run at idle. Check to determine if fuel pressure is within acceptable limits. See: Fuel Pressure > Pressure, Vacuum and Temperature
a. If pressure is low check for:
^ Plugged fuel filter
^ Restricted fuel line
^ Low voltage to pump (should be within 0.5 volts of battery voltage at connector).
3. Reconnect the vacuum line to the regulator.
If fuel supply and return lines are OK, and electrical supply and ground is OK, and fuel pressure is still low, replace fuel pump.

LEAKAGE TEST
1.Momentarily activate fuel pump by grounding test lead. Raise pressure to approximate operating pressure.
2.Remove ground from test lead and note pressure on gauge. Pressure should remain within 2 psi for 3 minutes after lead is ungrounded.
a. If pressure is not maintained check for leaking fuel
^ Lines
^ Connectors
^ Injectors
b. Disconnect fuel return line and plug engine side. Momentarily activate fuel pump by grounding test lead. Raise pressure to approximate operating pressure. If pressure holds replace regulator and retest. Reconnect the fuel return line.
If pressure is not maintained replace fuel pump.

For all these fancy Ford steps, it's really easier to just put a gauge directly inline with the in-tank pump output hose underneath the truck at the frame-mount pump input and energize the pump(s). This will measure the in-tank pump pressure only while still maintaining return system forward. Hard to find specs for, and I've only done this a couple times myself back in the nineties, so I couldn't tell you operating spec. Expect to see 8-12 psi though, and no leakdown. If you get nada, there's your main problem.

Also, the reservoir shown above MAY OR MAY NOT contain a cartridge-style filter inside. Only way to know for sure is to spin the reservoir off and check. If none there, no biggie, just replace that reservoir o-ring if it will not reseal. If there is a filter in there, my cake says it's still original, and could be the bane of all evil your system is currently suffering.

Any of these downstream issues will likely cause a volume/flow problem you will see on a pressure gauge up at the fuel rail though. Tape the gauge to your windshield, take a drive and see what happens to pressure under load. If you idle at 34/43 psi, and you nail it, pressure jumps to 43, then trickles down, down, down the longer you're WFO, you got low pump flow or restricted filters.

 

[mikefamig]

This is very helpful, thank you!

I've read this all and I think that I am beginning to see the big picture and I will re-read as I do some testing. So there is no check valve in the reservoir like I suspected. There are three check valves, one in the rear tank pump, one in the high pressure pump and one in the pressure regulator. I assumed that the system should hold pressure over night and it helps to know that it is normal for it to drop over a period of hours.

I have already done some testing with a gauge on the fuel rail. I get approx 40psi at full pump pressure and about 32psi at idle with regulator connected and ir goes back up near 40 running with regulator vacuum disconnected. I have also noted that after sitting overnight the pressure with first key-on is low. I don't remember the reading but it took a few key cycles on/off to get 40psi and then it still started with a lot of spinning and rough engine. I have already replaced the fuel filter on the frame rail so maybe a filter in the reservoir. I have read that my 89 should not have a filter but I think that I should remove the reservoir and open it up next.

The fact that it was still hard to start in the morning after cycling the key on and off and getting 40psi suggests that there is something more than fuel pressure causing me trouble. I am going to repeat that test later this morning.

Mike.

 

[Tiha]

Ditto on the flow testing, Pressure testing on the two pump system is not enough.

Also ditto on fuel pressure probably not being your issue, I was going to say cycle the key first as well.

 

[mikefamig]

I also added 32 oz of Sea Foam to the nearly full fuel tank.

Mike.

 

[mikefamig]

Ditto on the flow testing, Pressure testing on the two pump system is not enough.

Also ditto on fuel pressure probably not being your issue, I was going to say cycle the key first as well.

It is a little difficult to do inline testing with all of the fuel lines having O-ring type connectors. I have no way to connect a gauge to one of these connectors but I suppose that I can buy some connectors and make something up.

I am thinking that I can test the output from the in-tank pump by attaching a rubber line to the engine side of the reservoir which would accept a plain old rubber fuel line.

Mike.

 

[Motech]

So there is no check valve in the reservoir like I suspected.

I am not positive on that. If so, I have never traced retention loss to that unit. In fact, I have only ever had issues with them when they double as switching valves for dual tanks.

Maybe someone can chime in better, like @L\Bronco perhaps?

I am thinking that I can test the output from the in-tank pump by attaching a rubber line to the engine side of the reservoir which would accept a plain old rubber fuel line.

You could also simply disconnect main pump electrical conbector and see what you get at service port. Might take a few primes though, during which a deep funnel in your fuel filter neck will help you hear that pump running (or not?)

 

[mikefamig]

I am not positive on that. If so, I have never traced retention loss to that unit. In fact, I have only ever had issues with them when they double as switching valves for dual tanks.

Maybe someone can chime in better, like @L\Bronco perhaps?



You could also simply disconnect main pump electrical conbector and see what you get at service port. Might take a few primes though, during which a deep funnel in your fuel filter neck will help you hear that pump running (or not?)

I like the idea of unplugging the pump but is there a connector that is easy to get to or maybe a fuse or relay that I can unplug? Is there a connector on the pump itself?

 

[mikefamig]

I am not positive on that. If so, I have never traced retention loss to that unit. In fact, I have only ever had issues with them when they double as switching valves for dual tanks.

Maybe someone can chime in better, like @L\Bronco perhaps?



You could also simply disconnect main pump electrical conbector and see what you get at service port. Might take a few primes though, during which a deep funnel in your fuel filter neck will help you hear that pump running (or not?)

I have never seen any published Ford specs on fuel pressure retention beyond a couple minutes of rest time.

Let's say a single-tank, dual-pump system like yours in excellent condition delivers 34 psi regulated idle and 43 psi idle w/ regulator vacuum disconnected. When idling at regulated 34 psi, we can expect a pressure rise on shut-off about midway, say 38-39 psi that will still be holding when we come back five minutes later. An hour? 5-10 psi drop would not concern me, and overnight I would not be concerned if we found pressure had dropped to under 10 psi.

What would concern me is any immediate loss after engine shut-off.

Even moreso is ability to achieve full operating pressure with key-on prime the next morning. If you come out and see 5-15 psi after overnight soak, I would expect pressure to jump to full unregulated 43 psi in the first KOEO pump prime. If it pressure is zero, and it takes two or more KOEO prime events to achieve unregulated pressure, you have some delivery issues that need to be looked into.

Not counting injectors, you're going to have three anti-return "check valves" to consider: Regulator, in-tank lift pump and frame-mounted main pump set up like this:


View attachment 30391


The electric fuel pump system consists of two fuel pumps: a low pressure boost pump mounted in the fuel tank, and a high pressure fuel pump mounted on the frame rail. An in-line reservoir is located at the high pressure pump inlet. This design provides for satisfactory fuel pump operation during extreme vehicle maneuvers and steep vehicle attitudes with low-tank fill levels.

The low pressure electric fuel pump is used to provide pressurized fuel to the inlet of the high pressure pump and helps prevent noise, hot fuel problems, and prevent dirt and other particulate matter from entering the system. Any water accumulation in the fuel tank can pass through the filter without restriction.


View attachment 30392

The externally mounted high pressure fuel pump is capable of supplying 80 liters (21.2 gallons) of fuel per hour at a working pressure of 269.0 kPa (39 psi). The pump has an internal pressure relief valve to provide overpressure protection in the event the fuel flow becomes restricted. Overpressure is restricted to 950 kPa (138 psi) and reduced fuel flow will result. The system pressure is controlled by a pressure regulator on the engine.


I have seen in-tank pump failures that stress the pressure pump big-time and cause extended delays in system prime after overnight leak-down, with symptoms just like yours.

These systems require an additional step to determine which pump is leaking down. If your're losing pressure through the pump side (with return line blocked), then both pumps are shot. But if that rear pump is losing it's prime--or worse, not working--it will not show up with the front pump covering it's behind. You'd need to isolate that pump from the mix to know for sure.


STO Connector
View attachment 30390


STATIC PRESSURE TEST
1.Check for adequate fuel supply.
2.Turn key OFF
3.Install fuel pressure gauge to test port on fuel rail.
4.Install test lead to fuel pump lead of STO test connector.
5.Turn Key On Engine Off (KOEO).
6.Ground test lead to run fuel pump.
7.Check to determine if fuel pressure is within acceptable limits. See: Fuel Pressure > Pressure, Vacuum and Temperature
a. If pressure is low but greater than 3 psi (indicates fuel pump is running but not enough pressure) check for:
^ Plugged fuel filter
^ Kinked fuel line
^ Low voltage to pump (should be without 0.5 volts of battery voltage at connector).
^ Disconnect the fuel return line and note if fuel is being returned during this low pressure condition. If fuel is being returned, replace the fuel pressure regulator. Reconnect the fuel return line.
b. If pressure is less than 3 psi (pump not running) check for:
^ Defective fuse link
^ Inertia switch open
^ Wiring at fuel pump/tank connector loose or open
^ Fuel pump ground connection at chassis loose or defective
^ Improper fuel pump relay operation
If fuel supply and return lines are OK, and electrical supply and ground are OK, and fuel pressure is still low, replace fuel pump.

DYNAMIC PRESSURE TEST
1. Disconnect and plug the vacuum line to the pressure regulator.
2. Start engine and run at idle. Check to determine if fuel pressure is within acceptable limits. See: Fuel Pressure > Pressure, Vacuum and Temperature
a. If pressure is low check for:
^ Plugged fuel filter
^ Restricted fuel line
^ Low voltage to pump (should be within 0.5 volts of battery voltage at connector).
3. Reconnect the vacuum line to the regulator.
If fuel supply and return lines are OK, and electrical supply and ground is OK, and fuel pressure is still low, replace fuel pump.

LEAKAGE TEST
1.Momentarily activate fuel pump by grounding test lead. Raise pressure to approximate operating pressure.
2.Remove ground from test lead and note pressure on gauge. Pressure should remain within 2 psi for 3 minutes after lead is ungrounded.
a. If pressure is not maintained check for leaking fuel
^ Lines
^ Connectors
^ Injectors
b. Disconnect fuel return line and plug engine side. Momentarily activate fuel pump by grounding test lead. Raise pressure to approximate operating pressure. If pressure holds replace regulator and retest. Reconnect the fuel return line.
If pressure is not maintained replace fuel pump.

For all these fancy Ford steps, it's really easier to just put a gauge directly inline with the in-tank pump output hose underneath the truck at the frame-mount pump input and energize the pump(s). This will measure the in-tank pump pressure only while still maintaining return system forward. Hard to find specs for, and I've only done this a couple times myself back in the nineties, so I couldn't tell you operating spec. Expect to see 8-12 psi though, and no leakdown. If you get nada, there's your main problem.

Also, the reservoir shown above MAY OR MAY NOT contain a cartridge-style filter inside. Only way to know for sure is to spin the reservoir off and check. If none there, no biggie, just replace that reservoir o-ring if it will not reseal. If there is a filter in there, my cake says it's still original, and could be the bane of all evil your system is currently suffering.

Any of these downstream issues will likely cause a volume/flow problem you will see on a pressure gauge up at the fuel rail though. Tape the gauge to your windshield, take a drive and see what happens to pressure under load. If you idle at 34/43 psi, and you nail it, pressure jumps to 43, then trickles down, down, down the longer you're WFO, you got low pump flow or restricted filters.

I had a good find today. I left the fuel gauge on the fuel rail overnight and the first thing in the morning the fuel pressure was zero on the fuel rail. I turned the key on and got 38psi first shot. I started the engine and it spun a little longer than I would expect but it started and ran smoothly.

Last week I noticed some wetness in the dirt on the fuel reservoir so I cleaned and dried it up good. Today I crawled under there after a good ride and there is a small leak on the rear lower fuel line connector on the tank side which is the pump feed line from the tank. I'm hoping that just removing and replacing the connector will seal the o-ring and if not I'll need to learn to fix that connector.

Mike

 

[Motech]

I like the idea of unplugging the pump but is there a connector that is easy to get to or maybe a fuse or relay that I can unplug? Is there a connector on the pump itself?

They're just two spade connectors, a power and a ground that pull right off. And they can't be crossed either as a positive is larger than the negative.

You can see them in the shot in my first reply. Blow up the view of the pump on the frame rail, and you'll see where the two connectors plug in.

 

[L\Bronco]

Awesome info Motech, the only thing I would add would be to watch for leaking injectors. In my time at Ford I saw it enough. The factory testing was for pressure loss in 15 to 30 seconds.
A long crank with a short stumbly idle, then clear is either an empty fuel line (in tank check valve leaking) or fuel pooled in the intake runners (Leaking injectors)
Your pressure immediately comes up, so I would lean towards injectors. Not an easy test.
I used to pull the fuel rail and injectors up, out of the intake, leaving the lines attached. Then secure the injectors in the rail with zip ties and cycle the key several times to build pressure. Then watch for drips. (I'm too cheap to just replace them all)
I have seen good fuel systems hold 30 psi for several days. FYI
Hope that helps.
Cheers

 

[mikefamig]

Awesome info Motech, the only thing I would add would be to watch for leaking injectors. In my time at Ford I saw it enough. The factory testing was for pressure loss in 15 to 30 seconds.
A long crank with a short stumbly idle, then clear is either an empty fuel line (in tank check valve leaking) or fuel pooled in the intake runners (Leaking injectors)
Your pressure immediately comes up, so I would lean towards injectors. Not an easy test.
I used to pull the fuel rail and injectors up, out of the intake, leaving the lines attached. Then secure the injectors in the rail with zip ties and cycle the key several times to build pressure. Then watch for drips. (I'm too cheap to just replace them all)
I have seen good fuel systems hold 30 psi for several days. FYI
Hope that helps.
Cheers

The engine does idle just a little rough, not as smooth as I would like. Can the injectors be replaced without removing the upper intake manifold?

Mike.

 

[L\Bronco]

The engine does idle just a little rough, not as smooth as I would like. Can the injectors be replaced without removing the upper intake manifold?

Mike.

I'm not sure if you can sneak out the side under the plenum, but its not hard to remove the upper, if it has EGR remove the valve from the manifold and work around it, the tube usually breaks when you try to remove it.
And don't forget the hidden bolt in the middle under the plenum, (go in with a long 1/4" extension from the top), it's either torx or allen, I can't remember, sorry.
Cheers.

 

[mikefamig]

I'm not sure if you can sneak out the side under the plenum, but its not hard to remove the upper, if it has EGR remove the valve from the manifold and work around it, the tube usually breaks when you try to remove it.
And don't forget the hidden bolt in the middle under the plenum, (go in with a long 1/4" extension from the top), it's either torx or allen, I can't remember, sorry.
Cheers.

I'm not decided to do it yet but thanks for the info.

 

[mikefamig]

They're just two spade connectors, a power and a ground that pull right off. And they can't be crossed either as a positive is larger than the negative.

You can see them in the shot in my first reply. Blow up the view of the pump on the frame rail, and you'll see where the two connectors plug in.

I determined that the o-ring on the fuel reservoir is leaking so I plan to remove and re-seal it. I just removed the lower fuel line on the rear of the reservoir (goes to the tank) and gas is flowing out of it so I put it back on. Is this going to siphon the entire tank out of gas or is it just what is in the lines?

I had imagined that it would just drain a little from the line but it was a lot of gas that drained already and it was still flowing.

Mike.

 

[mikefamig]

I determined that the o-ring on the fuel reservoir is leaking so I plan to remove and re-seal it. I just removed the lower fuel line on the rear of the reservoir (goes to the tank) and gas is flowing out of it so I put it back on. Is this going to siphon the entire tank out of gas or is it just what is in the lines?

I had imagined that it would just drain a little from the line but it was a lot of gas that drained already and it was still flowing.

Mike.

OK I managed to remove the bowl from the reservoir with it still attached to the frame rail. My strap wrench was slipping but a piece of sandpaper wrapped around the filter bowl gave it some grip.

There was no filter in there and the seal is shot so I'm waiting for one from NAPA. I ordered a couple of o-ring part# 5347 for a couple of bucks which will not get here until late next week and I also ordered a filter NAPA #3268 which should be in my local store tomorrow.

If the seal from the filter does not fit then I will still have the other seals coming, otherwise I can cancel them.

Thanks all for the info that got me there painlessly. I'll update when I install the seal.

 

[chrlsful]

oh, I love a good story...
8^ )

 

[Motech]

I also ordered a filter NAPA #3268

If that is the cartridge filter for the reservoir, it will come with o-rings, including that elusive, large bowl seal.

My strap wrench was slipping but a piece of sandpaper wrapped around the filter bowl gave it some grip.

Ooh, see there? Even old dogs can learn new tricks!

Just last week I did a roadside inline fuel pump diagnosis and replacement on the side of a local mountain road for a real special customer's '88 dual-tank 4.9L E150. Took my 1/2" drive strap wrench and a Wix filter kit, but couldn't budge it. Luckily it ran strong with new pump, and I rescheduled her for service next month when I figured I'd wrench it off with my big Knipex water pump plyers.



So what grade sandpaper should I use?