Bronco Not Starting (Firing)

[lucky7_1080]

Hi folks - hoping someone here can help me troubleshoot a non-starting California '79. Here's the situation:

I fired up the truck one afternoon just to move it and clear the driveway. It started fine no issues, choked properly, warmed it up, kicked the choke off at the pedal after ~5m. Pulled it out of the driveway and onto our street, parked it uphill on a slight slope (20% grade). Ran great. It had been raining for ~2 weeks straight (truck is not garaged), and we had a clear no-rain day when I moved it.

About 4 hours later, I went to fire it back up and pull it back. I couldn't get it started, and couldn't get it to fire properly. So, I just dropped it in neutral and rolled it back to our driveway. Once there, and after letting it sit for 30m due to the possibilty of flooding, tried to get it to fire again. Checked to make sure carb was getting gas (it is). I was able to get it to fire, but had to keep the pedal buried and even then it was just barely running. When I let off the pedal, would immediately die. Timing issue? There is quite a bit of gas sitting on the sides of the carb, and on top of the intake manifold due to what I believe is failed gasket between carb and manifold. However, this has been in a failed state for last ~year and has been running fine with no issue. I ran through a series of troubleshooting:

- Tank is full of gas.
- Fuel pump is functional (it's brand new). Pulled fuel hose from carb inlet, turned it over, gas moving well.
- Fuel filter not clogged (per above).
- Checked all spark plug wiring.
- Pulled distributor cap, checked rotor and checked for moisture (both new).
- Coil sparking properly (pulled plug from cyl. 1, turned it over, strong spark.
- Replaced coil as test.
- Replaced ignition module as test.
- Solenoid and regulator brand new, putting out proper voltage.

Am curious if anyone has any thoughts here, specifically whether pulling it up on an incline could have had any impact.

Can provide more details as needed! Thanks all.

 

[Tiha]

Sounds like the engine is getting too much fuel and flooding out.

How long did you run it holding it to the floor? Did it ever clear up?

So sounds like a Carb issue. Float stuck, bad power valve, something allowing fuel to freely flow into the engine.
Mechanical or electric fuel pump? Electric pump could be over pressuring the float and forcing fuel by.

Those are my first thoughts, checks anyway.

Maybe you can pinch the fuel line with a vise grips and see if it clears up before it runs out of fuel?

 

[lucky7_1080]

Thanks @Tiha

I probably had it running for about a minute while the pedal was buried. My other thought here was that timing was off and the fuel that was making it to the top of the valves was dribbling in. And no, it never cleared up.

This is a mechanical fuel pump and brand new, working great. Even if I was getting “too much” fuel at cold start, I’d still expect it to try and fire - which it won’t do at all. We have tried to start it with no fuel line connected, just starter fluid and it’s not firing then either.

Thoughts on further carb investigation or timing check? (This is an oem motorcraft 2 barrel on a 6.6L)

A

 

[Tiha]

Not firing on starting fluid is always interesting. I suppose spark plugs could be wet and fouled, or you are getting no spark.

There is a cheap inline spark tester I like to use. Pictured below, available at places like harbor freight. You can verify spark to each cylinder, or at least coming out of the coil.
Then you know for sure.

If you know you are getting spark and it will not fire on starting fluid my next step would be compression test.
Compression test won't tell you if ignition timing is off, but it will tell you if cam timing is off. Could be timing chain jumped.

obviously you know more about the engine that any of us, but if I pulled it into my shop that is where I would start.

If you have compression and spark, then you know for sure it is a fuel issue.

In edit, Have you pulled the dipstick to make sure your oil pan isn't full of gas? That creates tons of other issues like flooding the engine with too many gasoline fumes and making it act flooded.

 

[L\Bronco]

Hi folks - hoping someone here can help me troubleshoot a non-starting California '79. Here's the situation:

I fired up the truck one afternoon just to move it and clear the driveway. It started fine no issues, choked properly, warmed it up, kicked the choke off at the pedal after ~5m. Pulled it out of the driveway and onto our street, parked it uphill on a slight slope (20% grade). Ran great. It had been raining for ~2 weeks straight (truck is not garaged), and we had a clear no-rain day when I moved it.

About 4 hours later, I went to fire it back up and pull it back. I couldn't get it started, and couldn't get it to fire properly. So, I just dropped it in neutral and rolled it back to our driveway. Once there, and after letting it sit for 30m due to the possibilty of flooding, tried to get it to fire again. Checked to make sure carb was getting gas (it is). I was able to get it to fire, but had to keep the pedal buried and even then it was just barely running. When I let off the pedal, would immediately die. Timing issue? There is quite a bit of gas sitting on the sides of the carb, and on top of the intake manifold due to what I believe is failed gasket between carb and manifold. However, this has been in a failed state for last ~year and has been running fine with no issue. I ran through a series of troubleshooting:

- Tank is full of gas.
- Fuel pump is functional (it's brand new). Pulled fuel hose from carb inlet, turned it over, gas moving well.
- Fuel filter not clogged (per above).
- Checked all spark plug wiring.
- Pulled distributor cap, checked rotor and checked for moisture (both new).
- Coil sparking properly (pulled plug from cyl. 1, turned it over, strong spark.
- Replaced coil as test.
- Replaced ignition module as test.
- Solenoid and regulator brand new, putting out proper voltage.

Am curious if anyone has any thoughts here, specifically whether pulling it up on an incline could have had any impact.

Can provide more details as needed! Thanks all.

Hi Lucky!
My thought would be a stuck float in the carb causing it to flood out. Or a ruptured power valve diaphragm in the carb. (its under the small round cover under the float bowl on the front side of your carb and likely the source of the fuel sitting on the intake.)
The quick check is to squeeze off the rubber fuel line that feeds the pump with vice grips or equivalent. Get it running again and play the throttle to keep it running.
If it clears up and then dies there is a strong likelihood the float was stuck.
It may come un stuck at this point. Take the vise grips off and try it agin. If its good now, the float was stuck, if not, go into the carb.
If it never clears up and dies, look into ignition.
Hope that helps
Cheers

 

[lynchsg]

Agree with stuck float. You explanation of gas on the manifold is an indicator of a stuck float which will flood the engine and keep it from s
Also you may have water in the gas. Remove fuel line at carb, crank engine with fuel line in a small clear water bottle, and fill it half way. Let it sit a while. If there is water in the gas it will be in the bottom of the bottle with the gas on top.

 

[lynchsg]

Keep it from atarting.
Sorry, phone operation issue.

 

[wyo58]

Hi folks - hoping someone here can help me troubleshoot a non-starting California '79. Here's the situation:

I fired up the truck one afternoon just to move it and clear the driveway. It started fine no issues, choked properly, warmed it up, kicked the choke off at the pedal after ~5m. Pulled it out of the driveway and onto our street, parked it uphill on a slight slope (20% grade). Ran great. It had been raining for ~2 weeks straight (truck is not garaged), and we had a clear no-rain day when I moved it.

About 4 hours later, I went to fire it back up and pull it back. I couldn't get it started, and couldn't get it to fire properly. So, I just dropped it in neutral and rolled it back to our driveway. Once there, and after letting it sit for 30m due to the possibilty of flooding, tried to get it to fire again. Checked to make sure carb was getting gas (it is). I was able to get it to fire, but had to keep the pedal buried and even then it was just barely running. When I let off the pedal, would immediately die. Timing issue? There is quite a bit of gas sitting on the sides of the carb, and on top of the intake manifold due to what I believe is failed gasket between carb and manifold. However, this has been in a failed state for last ~year and has been running fine with no issue. I ran through a series of troubleshooting:

- Tank is full of gas.
- Fuel pump is functional (it's brand new). Pulled fuel hose from carb inlet, turned it over, gas moving well.
- Fuel filter not clogged (per above).
- Checked all spark plug wiring.
- Pulled distributor cap, checked rotor and checked for moisture (both new).
- Coil sparking properly (pulled plug from cyl. 1, turned it over, strong spark.
- Replaced coil as test.
- Replaced ignition module as test.
- Solenoid and regulator brand new, putting out proper voltage.

Am curious if anyone has any thoughts here, specifically whether pulling it up on an incline could have had any impact.

Can provide more details as needed! Thanks all.

I think that everyone here has hit on most all of the problems it could be. water in fuel is also very possible. I dont think its your spark timing because it would be popping out of the carb or exhaust if it were off. The way fuel is these days, once the plugs foul they are usually done so you will probably have to change them out after you find the problem. The first thing that came to mind was the power valve was ruptured. easiest way to tell that is if you can get it running take a mirror and look down the carb, it will just be peeing out of the venturi nozzles. dont put your face there incase it backfires! Good luck!

 

[Motech]

This is an oem motorcraft 2 barrel on a 6.6L

Ethanol is hydroscopic, meaning that it really likes water and bond with it and sink to the bottom of the container real quickly. Once it does, as with us, that attraction will cause the two to become one in the form of a gelatinous blob that gets thicker with time. It quickly rust corrodes and rusts metal it comes in contact with as well.

Heavy rain will accelerate this process and cause any ethanol in your fuel to to gel up and sink to the bottom of your float bowl very quickly. Real common in carburetors more and more these days, and also EFI systems that have satt for a while. If addressed quickly enough, it can be easily remedied with a good cleaning, ie: overhaul.

I presume this isa Motorcraft 2150 series carburetor like this one:



If so, you are Lucky. Of all the carburetors out there, this is the easiest one to service. In fact, if you've never opened up and rebuilt a carburetor before, this is the perfect one to start with as they are very, very cooperative. Plus, every suggestion above will be covered in this procedure.

I recommend you get a carburetor rebuild kit. It will come with everything you need, like the gasket(s) you mentioned, plus new power valve, accelerator pump, float needle and seat, all the necessary clips hardware and very precise, easy to follow instructions with great illustrations. I highly recommend NAPA's Echlin brand. They're more focused, don't try to cover 15 years worth of carburetors in one kit, so they're not confusing.

Take your time with it, read the instructions carefully, take notes where you need to on adjustments, take a class or two at YouTube University and have at it. You're probably going to find that gel that I talked about down in the float bowl. Get it all out of there, clean it up, and have fun!

 

[lucky7_1080]

Thanks @Tiha and @L\Bronco.

Quick updates:
Plugs & Wires - Plugs are brand new. Less than 50mi. on them. None of them are firing. I've attached a photo of the front drivers side cylinder prior to starting the truck today. Heavy carbon deposits, not a great sign. Smelled like gas. After attempting to start, pulled the plug and it was wet. Gas is definitely getting to the plug. Used the check light tester mentioned in Tiha's post on all cylinders. Every single plug is getting spark and firing at a regular interval.
Compression Test - About six months ago, I had my local mechanic perform a compression test and all cylinders were in spec. One or two of them were out more than others. I've never done this myself, but assume I'd need an assistant and a gauge. Would love some guidance on this.
Timing - What I'd really like to do is to confirm whether or not the chain has jumped a couple teeth on the cam (or either) gear. Obviously I can't check timing / advance if the engine isn't running. What's the best way to do this?
Fuel Delivery - I crimped the fuel line just before entering the pump (coming from tank) as suggested. I cranked the engine for about 45-60 seconds and couldnt get it to fire. There was a strong smell of gas in the engine after attempting this.
Dipstick - Pulled the dipstick and there was no strong smell of gas on the stick. Oil levels still in spec.
Carb - Haven't cracked the carb open (ever). Any guidance or posts on what I should be looking for? I do have a rebuild kit, should I just go for it? I believe this is the original Motorcraft 2-barrel. All of the components attached also appear to be OEM (advance, choke, etc.) Considering that the plug was wet when I pulled after a quick crank per above, wonder if carb is really the next item to troubleshoot...

Thanks both!!!

L7

 

[lucky7_1080]

Thanks @Tiha and @L\Bronco.

Quick updates:
Plugs & Wires - Plugs are brand new. Less than 50mi. on them. None of them are firing. I've attached a photo of the front drivers side cylinder prior to starting the truck today. Heavy carbon deposits, not a great sign. Smelled like gas. After attempting to start, pulled the plug and it was wet. Gas is definitely getting to the plug. Used the check light tester mentioned in Tiha's post on all cylinders. Every single plug is getting spark and firing at a regular interval.
Compression Test - About six months ago, I had my local mechanic perform a compression test and all cylinders were in spec. One or two of them were out more than others. I've never done this myself, but assume I'd need an assistant and a gauge. Would love some guidance on this.
Timing - What I'd really like to do is to confirm whether or not the chain has jumped a couple teeth on the cam (or either) gear. Obviously I can't check timing / advance if the engine isn't running. What's the best way to do this?
Fuel Delivery - I crimped the fuel line just before entering the pump (coming from tank) as suggested. I cranked the engine for about 45-60 seconds and couldnt get it to fire. There was a strong smell of gas in the engine after attempting this.
Dipstick - Pulled the dipstick and there was no strong smell of gas on the stick. Oil levels still in spec.
Carb - Haven't cracked the carb open (ever). Any guidance or posts on what I should be looking for? I do have a rebuild kit, should I just go for it? I believe this is the original Motorcraft 2-barrel. All of the components attached also appear to be OEM (advance, choke, etc.) Considering that the plug was wet when I pulled after a quick crank per above, wonder if carb is really the next item to troubleshoot...

Thanks both!!!

L7

...with photo

 

[Tiha]

The compression test pretty much verifies that the Cam timing is okay. At least okay enough it should run. So no need to follow up on that.

That spark plug is extremely rich. Too much fuel and some oil.

I would venture to say it is fouled.

So you have spark going out to the plugs that is great.

Now I would take that spark plug, ground the thread area against the block and have someone crank the engine to make sure you see the plug spark. If it is not sparking you have bad plugs.

 

[Motech]

If you crimped the wrong line--the smaller fuel return--then you "dead-headed" the pump and forced over 100 psi through the injectors. That'll cost a flooding, smell of raw fuel, and blackened spark plugs if you got it to run that way.

 

[lynchsg]

Isn't a 79 carbuerated?

 

[wyo58]

Isn't a 79 carbuerated?

Agreed it has to be carbureted for sure, so it should be a mechanical pump.

 

[lucky7_1080]

@Tiha thanks - Yes pulled a plug and tested and it’s sparking well.

@Motech - There’s no fuel “return”. Crimped the supply (from tank) just prior to the pump. (Flex line between pump and stainless along frame.)

Thoughts at this point? Proceed to rebuild carb?

 

[wyo58]

...with photo View attachment 30914

Plugs are deffo fouled replace them when you can. You really need to try and get it running to tell what is wrong in the carb.

 

[lucky7_1080]

I pulled the carb. Oh boy.

First thing: there was about 1/4" of gas sitting on top of the engine. (You'll also note that the choke heater tube snapped off where I'm pointing from the mounting plate during de-mount, lots of rust.):



The passenger side port on the EGR valve / plate was completely clogged with fossilized oil:


The venturi needle? brass housing on the drivers side was cracked and split. The passenger side has a hairline and imagine will open up in time:


And last but not least, the power valve gasket appears to have a crack. The spring/valve weren't operating completely perpendicular to the plate:


Some questions here:

1) My rebuild kit came with the thick (1/4") gasket that sits between the carb and the EGR plate, but not the gasket between the intake manifold and EGR plate. As you'll see from the first photo (and below), the gasket that was mounted on my engine had a special cut-out connecting barrel to barrel:


Obviously, I'll need to replace this gasket. All of the aftermarket EGR to manifold gaskets look similar to this, without the special cut-out:

Will this "closed off" gasket still function properly? Assume so since EGR plate connectivity will go "over the top" of the gasket.

2) Does the cracked venturi matter? Should I replace this part of the carb? Carbs Unlimited has this aftermarket assembly.

3) Any thoughts on what if any carb components caused the gas to sit on the top of the engine / inside the intake manifold? Is there still a possibility that there's a timing / valve issue here?

4) Any suggestions on how to get the extra gas out of the intake? Not crazy about using a wet vac (fumes). Siphon?

5) Any suggestions on how to repair the broken choke heater tube? Having a hard time finding the entire plate assembly online.

Thanks all.

L7

 

[Motech]

Isn't a 79 carbuerated?

Agreed it has to be carbureted

My vad, I got my threads confused.

 

[Motech]

Obviously, I'll need to replace this gasket. All of the aftermarket EGR to manifold gaskets look similar to this, without the special cut-out:

Will this "closed off" gasket still function properly? Assume so since EGR plate connectivity will go "over the top" of the gasket.

It will still function. The opened up gasket was designed to distribute EGR flow a little more evenly among all eight cylinders.

2) Does the cracked venturi matter? Should I replace this part of the carb? Carbs Unlimited

I want to say don't sweat it, but can't without viewing in hand. Sorry.

3) Any thoughts on what if any carb components caused the gas to sit on the top of the engine / inside the intake manifold? Is there still a possibility that there's a timing / valve issue here?

Yes. Your power valve is clearly ruptured. That's it right there.

A new float is in order too unless you pulled a brass unit out of it.

4) Any suggestions on how to get the extra gas out of the intake? Not crazy about using a wet vac (fumes). Siphon?

Sop it up with stout paper towels and let the residual evaporate (if it hasn't already).

5) Any suggestions on how to repair the broken choke heater tube? Having a hard time finding the entire plate assembly online.

If there's enough broken tube on each end to connect them with some hose, a piece of EGR exhaust pressure sensor hose from a later model engine will do the trick. Look up DPFE hose for, say, a 99 F150 with a 4.6 or 5.4L and grab a few inches of the larger size.