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Engine runs then cuts out and won't start

PaulN

Jr. Member
Joined
Oct 5, 2013
Messages
103
So I've been trying to troubleshoot the last few days but my knowledge isn't the best but I'm learning quickly and thought I'd reach out and see if anyone could point me in the right direction. Thinking it is some sort of fuel delivery issue but not sure and have been looking through some older threads to come up with a solution.

I have a carbureted V8 302 with a C4 transmission about a year old gas tank and fairly new fuel pump. The other day I was driving down and out of nowhere the engine just cut out in the middle of the road. Luckily was able to start it back up after a few tries and then parked to take a look under the hood. Everything seemed fine and started back up again and was thinking maybe I had bad gas in the auxiliary tank or something but wasn't sure and drove a little longer without problems. Next day driving again for about 15 min and dies again at a red light. Couldn't get it started back up and had to get towed back to my house.

Checked out the distributor cap and rotor(only 3 months old) and there was a little bit of burning but not much corrosion. Tested battery voltage and seemed fine. Checked fuel lines to see if there was any cracks or leaks and didn't see any. Pulled air filter to see if I was getting fuel in the carb and seemed okay. And after letting it sit for an hour or so and sanding the distributor cap and rotor a little bit it started up again fine. An hour or so later without driving it, it wouldn't start again. Replaced fuel filter and started up fine and seemed to have a little bit more power when I was driving so I figured that was the culprit. Drove for an hour, stopped and restarted it a few times and everything seemed fine. Brought it back in the garage and 15 min later wouldn't start again and still hasn't the rest of the night. Pulled the gas cap to see if I could hear air being sucked and nothing.

I was thinking it maybe had something to do with the fuel lines getting hot because it started after it cooled down a bit but I'm really not sure what to check next or where to go from here. Anyone got any ideas? Maybe the starter? Or just not getting enough fuel? Not completely sure how to test my fuel lines besides checking visually. I also loaned up a compression tester and picked up a new distributor cap and rotor but maybe I am just going in the wrong direction.

Any and all help would be greatly appreciated and let me know if any pictures would be helpful too. Thanks in advance.
 
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PaulN

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Oct 5, 2013
Messages
103
Yes still have spark coming from the coil. But I will double check tomorrow because it just started up again. Haven't checked all the spark plugs but probably will tomorrow. Also I have been having a ticking coming from the passenger side valve cover so I'm not sure if I have a stuck lifter or not but wasn't thinking that had anything to do with this problem.
 

DirtDonk

Contributor
Bronco Guru
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Messages
47,275
Hey Boss, welcome to classicbroncos. And thanks for chiming in right away with a place to look too!

I'll add a few more tidbits, but by all means take BB's advice and look for spark. It sounds like it's cutting out instantly? That does not necessarily mean a fuel issue. More like a spark issue.
But as we know, it can be an 'all of the above" thing too with these old rigs!

Unfortunately too, "new" does not equal "good" anymore. If your relatively new fuel pump has sat more than it's been run, you really could have a fuel delivery issue. But that's easy to verify.
Next time it acts up, or if it's not running now, pull the air cleaner off and look for gas being squirted into the venturi when you manipulate the throttle lever.
And while you're at that, pull the coil wire out of the distributor, lay it near the engine or body (but not near the distributor if you can help it) and see if you have spark while cranking.

A few more Q&A's:

The other day I was driving down and out of nowhere the engine just cut out in the middle of the road.

Snap, like a light switch? Or a little bit of bobbling before it dies?
Do you have a tachometer? If so, next time it dies see if the needle drops to zero instantly, or if it keeps going as you coast to a stop.
If it keeps going a little bit, you still have spark in the ignition. If the needle just drops to zero, likely you have an electrical problem.

Everything seemed fine and started back up again and was thinking maybe I had bad gas in the auxiliary tank or something but wasn't sure and drove a little longer without problems.

Never had bad gas before, but my guess is it would not act like this. Bad gas is bad gas, and it's all bad in a tank or none of it is. If it runs fine half the time, then goes belly up, it's not very likely that the gas is bad.
Now, if half of the liquid in your tank is water... Then that's another story.

Tested battery voltage and seemed fine.

If the starter is doing all this cranking while you're trying to re-start with no problem, the battery voltage is good.
At some point all the cranking takes it's toll of course, but initially at least it sounds good if it's turning the motor over quickly.

Pulled air filter to see if I was getting fuel in the carb and seemed okay.

Meaning you could see the two good squirts of gas each time you rolled the throttle open?

And after letting it sit for an hour or so and sanding the distributor cap and rotor a little bit it started up again fine. An hour or so later without driving it, it wouldn't start again.

Sounding more and more like a spark issue. Gas in the carb is gas in the carb. If it lights up one moment but not the next while it still has gas in the carb, then it's not the gas.
At least not by itself.

Replaced fuel filter and started up fine and seemed to have a little bit more power when I was driving so I figured that was the culprit.

Would have been very unusual if that had been the issue. Not that filters don't clog up. The do all the time. But this is not acting like a clogged filter. Especially since you have gas in the carb.
A clogged filter usually lets you know by starving the engine for gas when under a heavier load, such as acceleration or climbing a hill, or just driving faster.

Drove for an hour, stopped and restarted it a few times and everything seemed fine. Brought it back in the garage and 15 min later wouldn't start again and still hasn't the rest of the night.

Typical electrical fault symptoms still.

Pulled the gas cap to see if I could hear air being sucked and nothing.

Good call. Always a good thing to check with these old vehicles.
What year is yours by the way?

Maybe the starter?

Physical impossibility.
The starter can't just kill an engine while it's running, and it can't keep the engine from starting if it's cranking just fine.
Well, there are ways it can do those things, but I think it would give other clues.

Or just not getting enough fuel?

Again, probably not. You disproved that theory when you found gas at the carburetor.

I also loaned up a compression tester and picked up a new distributor cap and rotor but maybe I am just going in the wrong direction.

Well, not likely a compression issue, as it would "normally" run funky all the time.
And maybe not a cap and rotor, but since you have them it can't hurt to try them.
What type of distributor? How old?

Any and all help would be greatly appreciated and let me know if any pictures would be helpful too.

Yes. Pictures, pictures, and then some more pictures.
Mostly under the hood at this point so we know what you have. Is it a stock engine? Heavily hopped up crate motor? Old stock wiring? Brand new harness?
How many miles on the vehicle? Engine? Other mods?
Stuff like that. The more info the better.

Nothing is etched in stone, and just when you think you have it figured out, it turns out to be something else. You might have a failing ignition switch or starter relay.
Blinker fluid and muffler bearings come to mind as well!
As Chris Jacobs, ignition guru of many years ago said, "Ninety percent of "ignition" problems are your carburetor, and ninety percent of your "carburetor" problems turn out to be ignition related."
So true, so true...%)

Paul
 

DirtDonk

Contributor
Bronco Guru
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Messages
47,275
Yes still have spark coming from the coil. But I will double check tomorrow because it just started up again.

Yeah, you have to check it when it's not starting. Since it's an intermittent problem already, you won't find it while it's running.

Haven't checked all the spark plugs but probably will tomorrow.

It's not a bad idea, but just be aware that short of four plugs going bad at once, an engine will still run. You don't get a running engine getting stalled out from just a few plugs or wires going bad. You'd have to lose four or more I would think.

Also I have been having a ticking coming from the passenger side valve cover so I'm not sure if I have a stuck lifter or not but wasn't thinking that had anything to do with this problem.

Likely not, but it's good to keep an ear on that problem too.

Paul
 
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PaulN

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Oct 5, 2013
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103
Thank you guys for the quick responses! Now let me answer a few questions and give some follow up. It is a 1969 and the engine is not stock but definitely not a crate motor. The PO told me it was from either an early 90s mustang or explorer but I am not totally sure and would love to know honestly. 60,000 miles on the engine. I think the wiring is mostly stock but has had some changes, no new wiring harness though. I believe it is a points distributor but maybe the pictures below can help and not sure how old it is but I have never changed it so at least 10+ years.

I do not have a tach but I think its definitely time to get one so I can get some better understanding. It was pretty quick not instant like a light switch but probably within 5 seconds.

I will check the spark again coming from the coil when it dies next time because it is now running again surprisingly but good to know that it is probably more of a spark issue. Well I don't know if that's good or not but all the explanation helps a lot. Yes I was getting two strong squirts when opening the throttle. Strong gas smell also. I included a few pictures of the top of the carburetor also but I am thinking that with extra time on my hands I might attempt rebuilding the carburetor if needs be. Haven't fully researched how hard that might be and whether it is a good idea or not but I am up for the challenge if so! Learned more in the last 2 months than I have in the last few years about the bronco.

Ive included some pictures below but can also give more. A little bit of a mess but am working on trying to get it cleaned up.
 

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DirtDonk

Contributor
Bronco Guru
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Hey look, another Franken-Bronco!
At least some of the body panels have been changed to those from a '76 or '77. You'd know instantly if it was a '77 though, by the gas door(s) on the side and the rear side marker lights being oriented vertically.
Then again, there are one or three '77's running around that did not get doors. At least one member here owns one of them.

Your wiring is newer than '69, the driver's wheel well is '76 or '77, the carburetor is '73 or newer, the horn relay makes it a '74 or newer, the orientation and location of the starter relay and voltage regulator make it a '73 or later too. As well as all sorts of other clues.
Other pictures of your frame indicate a '75 or earlier though (looks like a smaller trackbar bracket) so you have a real Franken-Bronco on your hands for sure.

The distributor was changed from points to an Accel points-eliminator kit. This could be a possible failure point. Even though the module itself can fail like anything else, I would say the most likely failure point would be at any PO made electrical connections.
Or the ignition coil perhaps?

Can you look at something closely for me? The driver's side valve cover has the fitting with the hose going up to the air cleaner housing. Correct?
Can you check to see how that hose is connected to the valve cover cap? Is that a PCV valve sandwiched between the hose and the cap by any chance?
You have an actual PCV valve with the metal base over on the passenger side and that appears to be connected to vacuum at the base of the carb. That's correct, but the one to the air cleaner must be just a simple hose arrangement. No fancy valves or anything. Just hose and whatever fittings are needed, but yours looks like it might have an original plastic base PCV valve in there.
If so, remove it.

Thanks for all the pics. Might really help us when we dig down deeper.

Paul
 
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PaulN

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Wow and to think this whole time I thought it was all a 69! Not totally sure about everything the PO said and he only had it for a few years before getting it from someone else so I am not totally sure and just listened to what he had said but could've been wrong forsure. I thought he had told me that the engine had been swapped but it was 8 years ago and don't fully remember. I thought when I had looked up the VIN number and tried decoding it that it was a 69 but I must have been doing something wrong. I'll take another look and try and see if I can find the VIN number on the frame under the passenger side because maybe the glovebox door had been swapped at some point.


As to the PCV valve it is not a plastic piece and have included a picture below.
 

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DirtDonk

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Perfect, thanks.
So is that a straight through fitting then? Just the vent it's supposed to be with no obstructions? If so, that's good.

Paul
 

DirtDonk

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It's still possible that the body panels were replaced, and that does happen often these days since you can buy the right wheel wells for different years, and firewall and cowl plates for different years, and your engine compartment was painted black so might have been worked on.

Is there still a door pillar certification decal as well?
Does the VIN match that on your registration?

And the next time you're out there with the camera, take a shot of the upper trackbar bracket. That will tell us what year range the frame is.

Paul
 
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PaulN

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Yes just a vent with no obstruction. Im thinking it is probably from a later year also. I included a picture of the trac bar also.
 

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PaulN

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Also UPDATE. It happened again and died almost instantly when I accelerated a little bit. Checked on the side of the road and wasn't getting a spark from the coil at all. Got it towed and back in the garage and now there is a slight spark but not much at all. Started looking under the dash to see if everything with the ignition switch was correct and saw this wire had come out. It doesn't seem to go to the ignition switch though and trying to find where it goes right now as it goes behind the heater tubing.

Anyone got any advice for no spark from the coil at all and now having a slight spark? Slightly confused by that and jump it around that or something? Im thinking it has to be a bad coil since at times I have been getting spark and then I don't so it wouldn't be a loss of power to the coil but the coil itself right? Could be wrong though. Not totally sure exactly how I do that but I have been reading some threads and things online trying to figure it out.
 

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Tuloyuser

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When it died how was the battery still charged? Also is the alternator charging the battery ok?



Sent from my iPhone using Tapatalk
 
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PaulN

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Oct 5, 2013
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103
Yes the battery was still measuring around 12 volts and the alternator is new and seems to be charging okay. Just not getting a spark from the coil so thinking about changing the coil.
 

oldiron

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Jul 21, 2005
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1,032
Change the coil. Cheap and easy, if the problem persists, look deeper.
Greg
 

needsmoarturbo

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May 13, 2015
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First thing that ever went out on my bronco was the coil. They do start cutting out when warm them work again after cooling a while. That's where I'd start. A new coil is fairly cheap and easy too!
 

DirtDonk

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My '68 has the letter D so I would think yours is after that, but they changed things a bit here and there during that time, so I can't really be certain.

And your frame is definitely not from a '76 so could be a '69. We need to decode the VIN deeper.
What does it say on the registration?

Paul
 
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PaulN

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Okay thanks so much guys just got a new coil and will replace that and hopefully that is the issue. Especially since the heat seemed to affect it. Is it worth it to upgrade the coil without replacing the distributor? I picked up a duralast 12v for electronic ignitions coil from the parts store because that is all they had. Im a little confused about the accel points eliminator kit...

And dang Paul well so is it because of the trac bar mount that it is not a 76 frame? Or more than just that.
 
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Kenny

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Jul 26, 2002
Messages
301
When you mentioned the problem, I thought to myself if you had a Mallory Unilite Distributor or Accel Points Eliminator Kit. I have a Mallory Unilite, and my ignition module inside the distributor went bad, and I had exact same problems. The Accel Ignition Module is very similar (if not the same) as a Mallory Ignition Module.....just different color. I just mention this, because I'm pretty sure someone replaced a Mallory with an Accel maybe 10-15 years ago and it worked. Back then you could get them in Auto parts store for around $30. Not sure now. Not saying you should just go out and change in, but it's a possible option.
 
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