Weird 95 Bronco Starting and Stalling Problem

[hladamjr]

I have a 95 Bronco XLT Auto Trans 302. Since it's gotten cold I have been having a weird and puzzling somewhat intermittent problemproblem. In the morning when the engine is cold I'll turn the key hear the fuel pump run up and stop after it's up to pressure, I'll turn the key and 75% of the time it will turn over and not start. If I let it sit with the key on occasionally I'll sometimes hear the pump come on again. When I do I'll crank the engine and it will start. Others times I'll turn the key off and back on and the pump runs and it starts. It will idle fine and I'll let it sit and warm up fora short period of time till it settles down to normal idle and then back out and start driving. It runs fine, no hesitation no nothing. I'll be driving and go through numerous stops and starts for lights, traffic etc, with idle fine and all that. Then after maybe 2-3 miles with engine temp now up to nomal I'll come up to a light and stop and it wil die. No cough, no hesitation nothing. I'll go to start it and it will crank but not start. If I let it sit for a few minutes and try again it starts and off I go. The rest of the day it's fine and won't repeat the cycle at all. I can stop and let it sit for hours in 30 degree weather and it's fine all day. The other scenerio is that if I do the above and I get on the interstate BEFORE it has stalled once I'll be driving along at 55 MPH normal temp etc and then all of a sudden the engine will die, RPM's drop to zero and then without taking my foot off the gas 2 seconds later it will pick back up and along I go the rest of the day no problems.

I have had it into my mechanic and he found no codes at all. I left it with him for several days so he could troubleshoot and he said he found corroded green contacts on the coil and was getting no spark when trying to start it. He installed a new coil and said he couldn't get it to re-occur. I figured it was resolved. Next morning after getting it back I went out and it started fine. Driving along and after several miles and normal temp etc it stalls out as before as I was slowing for a light. I pull over let it sit for 2minutes and it starts fine and runs the rest of the day.

I am puzzeled as if it were intermittent grounds or connections I would expect to see more random stalls etc to the problem. I almost think it is the EGR that may be hanging open ONE time and not closing when slowing or stopping and going to idle mode but that doesn't make sense for when it stalls on the highway. Doesn't make sense to me with this all happening once and then being fine he rest of the day

Sorry for the long windedness but I figured to little would prompt questions. hopefully you guys can give a little insight or have seen this before.

 

[Stubby1971]

This is a new one for me.. The question I have is- Did your mech check to see what the fuel pressure is going to the injectors? There should be a valve, like a bicycle tire valve, that he could hook a gauge too- I just wonder if it could be a weak fuel pump that acts up only in cold weather, the longer you drive- the warmer it gets. I also wonder if your mech stored the truck inside a heated garage and that's why he thought it was fixed. When you guys finally figure it out- please post here, I'd like to here what it ended up to be

 

[Seabronc]

I doubt that it is the EGR. It is very possibly a temperature sensitive or corroded connection. One of the connectors that causes a lot of intermittent problems is the one that passes the lines through the firewall, another one would be to the computer and perhaps the TFI module connector. Disconnect your battery and then take them apart, check the condition of the pins and reinstall them.

Good luck,

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[hladamjr]

I doubt that it is the EGR. It is very possibly a temperature sensitive or corroded connection. One of the connectors that causes a lot of intermittent problems is the one that passes the lines through the firewall, another one would be to the computer and perhaps the TFI module connector. Disconnect your battery and then take them apart, check the condition of the pins and reinstall them.
Good luck,

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Yes He checked the fuel pressure and it was fine, forgot to mention that piece. I left the vehicle with him over several days and it was left outside so it would be cold. He did the cold condition testing outside so that was under the same conditions and the temps over that period were the same.

I'll check the connectors and see what I find. I am somewhat confused and not confident of finding an intermittent connection however. I say that because I have the problem in the morning after sitting over night (12 hours approx) but not in the afternoon after sitting 4-5 hours. It's cold enough for a connection to "cool down" I would think. I'll still make the checks and keep you guys posted.

Thanks in advance.

 

[Seabronc]

Unfortunately, this type of problem is the most difficult to find and the most aggravating. At least we have it narrowed down to your Bronco /emoticons/[email protected] 2x" width="20" height="20" /> .

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[Shadow_D]

This sounds exactly what mine has been doing, I have located the problem but have NOT figured out why.

Under the hood on the drivers side there is a fuel pump relay that may be going bad or it could be corroded in the contacts.

First when it is acting up tap on that relay, you should hear the fuel pump pressurizing the system now it should start.

Next go to your local auto parts store and get a new pigtail and fuel relay, there are 2, a 5 wire and a 4 wire, make sure you get the right ones.

 

[hladamjr]

This sounds exactly what mine has been doing, I have located the problem but have NOT figured out why.Under the hood on the drivers side there is a fuel pump relay that may be going bad or it could be corroded in the contacts.

First when it is acting up tap on that relay, you should hear the fuel pump pressurizing the system now it should start.

Next go to your local auto parts store and get a new pigtail and fuel relay, there are 2, a 5 wire and a 4 wire, make sure you get the right ones.

Ok I picked up a new relay and replaced the Fuel Pump Relay this afternoon at lunch. This morning it started fine, let it warm up 10 minutes drove a mile down the road and stopped to get gas. Went to start it and it just turned over and didn't start. Turned the key on and of over a period of 5 minutes maybe every 30 secs or so i guess. It started finally and was fine the rest of the way to work (20 miles). I picked up a new relay and replaced the Fuel Pump Relay this afternoon at lunch. Started fine and back to work then (20 miles). I'll post more after tomorrow as the temps are to be in the 20's over night and 30's in the daytime.

Didn't pull connectors on the firewall yet for poor connection possiblilties. With it cold out I am trying to hit the easy stuff first since once it "gets It out of it's system" in the morning it's fine the rest of the day.

More to come

Thanks again

 

[hladamjr]

Well finally got things straightened out . Ended up being the Hall effect in the distributor. power would be fine but no PIP out of the distributor when it wouldn't start or when it died. Replaced it and it's fine. I have never seen one that goes bad then good and at such a reliable point. I really figured it was a sensor that was failing at a the point ot the computer going from open loop to closed loop. But I'm just glad it's strighteded out.

 

[cawabronco]

Unfortunately, this type of problem is the most difficult to find and the most aggravating. At least we have it narrowed down to your Bronco /emoticons/[email protected] 2x" width="20" height="20" /> .
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Speaking of broncos ,that one fine Bronco in your pic. Is that old school Ford?

 

[Shadow_D]

Glad to hear you got it solved.

 

[Seabronc]

Speaking of broncos ,that one fine Bronco in your pic. Is that old school Ford?

32 Ford pickup, unfortunately not mine. Just one of the eat your heart out vehicles at the Good Guys East Coast Nationals last fall. I use to have a 31 Ford rumble seat coup.

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