Common primary ignition problem?

[BroncoJoe19]

I have a '90 302 that hot or cold, intermittently stalls. It will restart as though there is/was no problem at all. It may run for hours with no problems, or just minutes. The check engine light may come on, but I had it in the shop, and it doesn't throw any codes.

I suspect that it may be a weak connection somewhere in the primary ignition system. Maybe the ignition switch, or the leads to the coil, but before I do a lot of testing, and hair pulling, I wonder if any of you know of a particular problem inherent to old Broncos that I should check first.

BTW... the fuel pump and filter are relatively new, and I had replaced the cap and rotor.

Thanks in advance

joe

 

[Seabronc]

Does it act as though someone reached over your shoulder and turned the key off? If so, on older Duraspark electronic ignitions that was a classic symptom of a bad pick up coil in the distributor especially if it is followed by the symptom of it starts right up after having set for a while. With the ones in your year range the symptom was also exhibited by the TFI module that is sticking out of the side of the distributor. Of course it could be numerous other things like a loose wire so parts replacement as a trouble shooting strategy is not a good procedure since you end wasting a lot of money on good parts.

Good luck,

>-

 

[BroncoJoe19]

Does it act as though someone reached over your shoulder and turned the key off?

Hey Seabronc, thanks for the reply.

It behaves more like it is starving for fuel, before it shuts down. It will restart immediately, no need to wait for anything to happen. It has me thinking that it might be the ignition switch, with a ****** connection or something like that. I tried wiggeling the keys, and slightly turning the keys in the switch a little, as it was acting up, and I can't say for sure that it makes a difference.

Does that help narrow it down a bit?

Thanks again,

joe

 

[Broncobill78]

I've had the same problem in the past with a few of mine. Like SeaBronc said it's frequently in the distributor. The ignition module can also be a culprit here, aftermarket modules in particular. I went thru a string of them on one of my Bronco's & replaced 4 of them within 15 months before I got tired of the grief & just bought a MotorCraft module & never had another problem with the ignition. The aftermarket modules are cheap because they're cheap

 

[BroncoJoe19]

Guys, I appreciate the responses,

before I go on a parts changeing expedition,

Here is what was suggested as the possible culprit:

1. bad pick up coil in the distributor

2. the TFI module that is sticking out of the side of the distributor

3. The ignition module

4. loose wire

A couple of weeks ago, I had it to my mechanic, who checked it for me and said that it didn't throw any codes.

Of the things listed above, which ones are most likely to cause my problem, and NOT throw any codes? I don't have a clue.

BTW... My son changed the ignition module about a year ago. I don't know what brand he used. Also I don't have the truck here, (it is about 25 miles away) but I may not have a TFI ignition system, I'll check that on Wednesday.

Thanks again,

joe

 

[Seabronc]

On further thought, based on your response, I'm leaning away from the ignition all together. If it has the feel of a fuel starvation problem, then maybe that is it. Possibly the filter or crap in the gas tank getting sucked up to the screen around the pickup. You also have two fuel pumps and if one of them is getting flaky, you will get fuel starvation. None of these will throw codes at you.

Good luck,

>-

 

[Broncobill78]

Well, it shouldn't be too hard to ck the fuel pressure & see if it's low or maybe fluxuating. How long since the fuel filter was replaced ? It's certainly further down on the list (because it sounds like more of a fuel *delivery* prob) but I've seen injectors lose power intermittantly due to a bad harness (but that one sputtered and ran poorly for a few moments before dying completely). But even when the pump cuts in & out I've never seen one that simply *stopped* when the pump quit, they choke & chug for a moment or two first.

When it does, just how does it die ? Is it quick like you've turned the key and made the spark go away or does it take a few seconds like it's sucking the line dry ? I think the manner in which the truck dies will give you the best clue as to where the problem lies. You should be able to *feel* the difference between a spark problem & a fuel problem.

 

[brandcole73]

I had a 95 that did about the same thing. Sometimes it would start right back up, sometimes it would be hours later before it would start. It would go for a month with no problem, then do it 3 times in one day. We could never get a code because it allways ran fine at the shop. I started putting parts in it to no avail. Finally it did stall in the shop parking lot and we were able to get the code while it wouldn't fire. It was the sending unit on the distributer (TFI?) $50 to fix it. I wasted about $1400 changing other parts before this. I'd definatly change this first!

 

[BroncoJoe19]

Well guys,

I appreciate all the help and support. I had a little time on my hands today, so I took a drive and brought the Bronco back home so I can take a look at it. I put about fifty miles on it today, in the rain, and there were no problems. I stopped by a local parts store to buy a fuel pressure tester, and they were out of stock of the high pressure type. Maybe tomorrow.

The pump is less than a year old, and the filter has about a tank of gas through it.

Here's my plan for now.

Buy a fuel pressure kit tomorrow, and test it.

If I don't find anything, I will keep it in the truck, and when it acts up, I'll try to test it then.

So, in the mean time I pulled out my Haynes repair manual, and looked under the hood. I now know that I have a 5.0 EFI engine with an in tank fuel delivery module (FDM). It appears that I have a TFI ignition system.

These intermittent problems are a pain. I want to get out and play, but am afraid that I'll get stuck.

At any rate... thanks guys.

joe

 

[Seabronc]

If you can, leave it hooked up so you can see if that is it when the problem is in progress. Fuel starvation due to pumps or filters may look normal after you stop since the problem may clear. Like I said before crap in the tank may be being sucked up against the pick up screen or one of your TWO fuel pumps may be getting flaky. You have a low pressure pump in the tank and a high pressure pump on the frame rail just about under the driver seat. If the high pressure pump is crapping out the low pressure pump can't keep up with the demand.

Good luck,

>-

 

[Broncobill78]

SeaBronc's right. The *best* thing you can do both NOW for your diagnostics and later on when the need will eventually arise again will be to get an in-cab fuel pressure gauge that you can plumb in under the hood & run to an in-cab gauge. Fuel pressure can be tricky and I just can't *tell* you how many problems it's caused. Very often after you've shut down & restarted it will be fine so using a temporary gauge will frequently miss the problem. Running something in-cab will give you the opportunity to monitor the pressure real-time and not only watch it as you drive but see what it's doing when you truck is acting up. It can be indespensible for troubleshooting something like this. The only other thing that would even be comprable would be something like a data-logging hard-drive that can monitor and store the parameters of what your truck is doing so that you can ck the logs after a failure to see what's what but that can be an expensive & tedious operation and not one I'd be keen on getting involved with, but more than a few dealerships have one. A simple in-cab gauge can make a huge difference by providing critical info.

 

[BroncoJoe19]

If you can, leave it hooked up so you can see if that is it when the problem is in progress. Fuel starvation due to pumps or filters may look normal after you stop since the problem may clear. <snip>Good luck,

>-

BroncoBill78... SeaBronc's right. The *best* thing you can do both NOW for your diagnostics and later on when the need will eventually arise again will be to get an in-cab fuel pressure gauge that you can plumb in under the hood & run to an in-cab gauge.

See... this is why you guys are the Best!

Even if all of the buttons on your dash don't work <grin>

Soooo... I'd like to make this as painless as possible. I guess I should try to get some kind of a fuel pressure sending unit that I could ***** onto the shraeder valve on the fuel rail, with an electric guage placed in the cab?

Any other more feasible suggestions?

Thanks again,

joe

 

[Broncobill78]

I guess I should try to get some kind of a fuel pressure sending unit that I could ***** onto the shraeder valve on the fuel rail, with an electric guage placed in the cab?

Yup, that's the way I'd go. I never liked running a mechanical fuel gauge into the cab when my trucks were *carburated* and doing so with fuel injection would just be insane. You definately want an in-line sending unit running to an electrical gauge in the cab. I would also pickup a second gauge to mount under the hood so you're not having to duck back into the cab to ck it while working on the truck. I often find that having cheap fuel & oil pressure gauges mounted to the firewall under the hood saves me a lot of hassles like that.

I can think of cheaper ways to do it but none that would be safe enough to suggest to someone in a public forum, and again this is all assuming that the problem is fuel related. If the thing is just dying suddenly like you've turned it off then I would lean towards a spark problem (lot of bad TFI modules out there). I still think the *manner* in which it dies will point towards the problem.

 

[BroncoJoe19]

Yup, that's the way I'd go. You definately want an in-line sending unit running to an electrical gauge in the cab.

Woooah Nelly...

I went to a couple of parts stores today, and was directed to a speed shop, where I was told that an inline sending unit and guage would cost about $400.

That won't fix the problem, but only let me know if I am on the right track.

So now I am thinking... I'll just wait for the darn thing to get worse until it isn't an intermittent problem any more.

Today, I bought a fuel pressure tester, I checked the pressure with the engine off, the engine on, and did a static pressure leakage check (which checks the pressure regulator to some extent.) It all checked out.

I threw in a bottle of fuel injector cleaner, and my son and I changed the plugs. It was a shame to see that original equipment hit the pail 8-( Well, at least the plugs LOOKED like they were original equipment.

I hope you guys have a great new year, and thanks for all your help.

joe

 

[Broncobill78]

Well to be honest I prefer the term "whoa there Hoss" (So I'm a big Bonanza fan, I mean, who DOESN'T love Bill Shatner ?) but back to the point. No, this stuff ISN'T cheap. Now by any chance does the owner of said parts store happen to tool around in a Benz or a Bently ? Because they're quoting you prices that are roughly *twice* what you should be paying. Now you maybe need to understand the hardware needed to SAFELY & accurately bring fuel pressure readings *into the cab of your truck* does NOT cost $25. On the other hand it should NOT cost $400 either. You also need to be able to do some of this work on your own instead of just handing it to a mechanic & writing a check, otherwise it once again becomes expensive because that's the nature of modern vehicles. This is what *I'd* be looking at:

http://www.jcwhitney.com/autoparts/Product...0007404/c-10101

and pls keep in mind that I mentined from the *start* that it was important to understand just HOW your truck wat dying so it could be better localized as to whether it was a fuel problem or a spark problem. It isn't always cheap to diagnose a problem and sometimes the $$$ you spend has to be considered a future investment because once it's in it will help maintain the truck & troubleshoot future problems.

There are alternatives that are even cheaper than what I've posted (mostly because you have to do more work and because they're mechanical gauges instead of electrical)

http://www.jegs.com/webapp/wcs/stores/serv...760855_-1_10677

http://www.jegs.com/webapp/wcs/stores/serv...761355_-1_10677

http://www.jegs.com/webapp/wcs/stores/serv...745259_-1_10677

http://209.85.207.104/search?q=cache:gWP_X...cd=10&gl=us

Please keep in mind that the MOST EXPENSIVE route to fixing a problem is going to be walking into the shop and asking them for what you want. troubleshooting & repairing problems like this will almost always involve doing your own footwork to find the cheapest parts/kits and then turning your own wrenches.

This is an excellent example of why it's good to try and narrow down the scope of your problem rather than taking the shotgun approach. NO, this stuff isn't cheap, not even when you shop around. So it's generally in your best interest to do everything you can to figure out *why* your truck is doing what it's doing before you start spending cash on diagnostic tools or fixes. You should do your best to figure it out first and then spend the coin on confirming it.

 

[Seabronc]

I threw in a bottle of fuel injector cleaner, and my son and I changed the plugs. It was a shame to see that original equipment hit the pail 8-( Well, at least the plugs LOOKED like they were original equipment.

Don't know why I didn't think of this before but I hope you did wires, rotor and, cap with that /emoticons/[email protected] 2x" width="20" height="20" /> . A high voltage leak can cause similar problems. Old age I guess -_- /emoticons/[email protected] 2x" width="20" height="20" /> . That is just another stab in the dark, and like Dave said, do a little trouble shooting. One way to look for high voltage arching is to do it after dark, open up the hood and take a spray bottle and make a mist around the engine. It is especially a possibility if this problem is happening when there is a lot of moisture from rain, melting snow, etc.

By the way, if you did or do change them, get some dielectric grease and put a little around the inside of the spark plug boot. You don't need to glob it on, just wipe a light coat around the insulator on each plug and the inside of each plug boot. Make sure you get the boot on all the way and that it stays, (slip it on and tug slightly on it to make sure it is actually on), sometimes they seem to be on but are not on all the way and slip back while the engine is running. Also do the distributor end, (this end is a little more tricky since the seal traps air and attempts to hydraulically push it back off), I use a small right angle pick to hold the edge of the distributor end boot off while inserting it.

Just another thing to think about, you reconnected that brain cell when you mentioned the plug condition .

Happy New Year!!! /

>-

 

[BroncoJoe19]

So now I am thinking... I'll just wait for the darn thing to get worse until it isn't an intermittent problem any more.
joe

So guess what? It's worse.

OK.. so I hooked up my fuel pressure guage, and found that the pressure remained pretty constant, and always within range even when the engine stalled. Lucky me... I just saved myself $200. BTW... thanks BroncoBill for the URLs for less expensive guages.

Next I got out a spray bottle, filled it with water as spritzed the wires. that didn't make anything any worse, so I turned it to stream, and downright got them good and wet. Nope... it looks like the wires are in good shape. Yes SeaBronc, I had replaced the cap and rotor.

SO I tested the primary winding of the coil, but wasn't sure if I tested the secondary windings properly.

I tried to check the air cleaner, but two of the four screws were spinning but not coming out. I quit just before going to get my sawzall. That'll be a task for another day.

I also tried to pull my PVC valve, but it is really hard to get to, and I was afraid that if I got it out, I may not be able to get it back in, so I skipped that too.

At this point I started considering just buying new parts and putting them in, or taking it to a local mechanic who is supposed to be pretty good, or taking it right to FORD. Then it struck me... NOW that it is bad enough.. maybe it will throw some diagnostic codes!?

So I got out the book and read about how to test for codes without any special equipment. I tried it, and son of a gun... it worked!

I gotta tell you, that was pretty damn exciting. The last time I worked on cars was in the '70s, and that was on cars built in the 60s (points, condensers, and carburetors). A year ago, I thought I would replace the plugs on my Crown Vic, and couldn't find them. I started to remove this long tube to get it out of the way, and son of a gun... gas came out of it!

OK, so I got a code 22 which means my MAP sensor is out of range.

So, do I just replace the MAP sensor? Or is it more likely that it is working, and is reporting another problem that needs to be fixed?

BTW BroncoBill, I am sure that Shatner would love to have your nickname. He would mount any alien, whether she was green, or was a thousand years old.

Again thanks guys,

joe

 

[Seabronc]

A MAP sensor code could be the sensor is out of whack or it is reporting an air flow problem. My wife's car had a problem reported as a MAP sensor and it turned out to be the intake tube following the sensor had a crack in it and the engine was getting air through the crack and the sensor didn't know that. It was reporting a low air flow. Can't say this is your problem, but take a look at the condition of the tube and and clamps holding it on.

Good luck,

>-

 

[BroncoJoe19]

A MAP sensor code could be the sensor is out of whack or it is reporting an air flow problem. My wife's car had a problem reported as a MAP sensor and it turned out to be the intake tube following the sensor had a crack in it and the engine was getting air through the crack and the sensor didn't know that. It was reporting a low air flow. Can't say this is your problem, but take a look at the condition of the tube and and clamps holding it on.
Good luck,

>-

Here's a little update.

Today I only had an hour to work on the truck, tomorrow probably more.

I looked for vacuum leaks and found none, so I replaced the MAP sensor. I was told to leave the battery disconnected for at least twenty minutes to clear the memory of the computer, so in the mean time I put time into getting the air cleaner housing apart. Well, I think I found the reason why the MAP sensor was complainng about not getting enough air. ;-/ I guess the last two owners of this Bronco didn't change the air filter, I don't think I had ever seen one quite so dirty.

So I finally started the truck up, and it is not any better.

I hope that this is a new problem caused by changing my plugs. Here are the new symptoms.

It has no power what so ever. It has a miss, or two, and may be backfiring a little. I just went out and checked to make sure that we didn't cross any wires, and we didn't. The boots of the wires were well adheared to the plugs, there were at least three of them that I could not get off. I offered to go buy one of those special pliers for pulling the boots, but my son managed to get them off. IF he just pulled on the wires, he may have broken them inside, no?

Tomorrow, I'll pull them all, one by one, put the dielectric grease on them (that we didn't do) and make sure they are all well seated. The bronc's check engine light came on, so I will also check for any new codes. Damn... I thought I was going to be finished... oh well I'll report back with my progress tomorrow before the Giants play at 1:00. Hopefully I'll have good news.

Will duct tape work on ignition wires?

just kidding.

joe