Won't start when there's heavy dew.

[Scott8]

So I would routinely discover that my Bronco won't start in the mornings when I would attempt to start it up and drive to work. I'd be super frustrated, buy a part that I thought might be the problem, install it, and presto. It starts up, I feel like a million bucks, then the next morning, it doesn't start again. I brought it to two different mechanics. For them, it started up every morning just fine. I bring it home, and once again, it won't start in the morning. I live near a river in low-land in North Caronlina. I believe I have more dew at my house than the mechanic shops which are in the city on higher/dryer ground.

Its a 96, 5.0 Bronco built in Venezuela, so has mostly 93-96 parts in it. I've already replaced the fuel filter and fuel pressure regulator. I'm guessing it is some plastic part with a leak/crack in it, and it allows dew inside to short out the system. It will crank good, so I don't believe it's the battery or starter. Any ideas on what might cause this? Anyone ever have this problem?

I appreciate the help in advance. I'm youTube trained, so that means I'm pretty dumb when it comes to this kind of troubleshooting.

 

[Whipsaw]

First off, if you don't have a code reader, run by Advance or Autozone and get the codes read, that may give you some good clues. On my 2001 Explorer, it won't start if the column shifter isn't fully up, after years of wear sometimes it needs a little push up on the shifter, not sure if the Bronco has the same set up. Intermittent no-starts are a challenge, does it happen when it's cold out or just wet?

Here's another thread with several troubleshooting approaches. I.e. fuel pressure, ignition system, etc.

Crank but no start issue on a 95 XL 5.0

Hi everyone. Longtime lurker who has benefited from many posts. I’ve got a “crank but no start” issue with my 95 Bronco XL 5.0 (225k miles) that has me really banging my head against a wall. A few months ago I had the old starter go out, so I replaced it, along with the starter solenoid. It...

www.broncozone.com

 

[Scott8]

Thanks. I have an OBDII but even though it's a 96, it still has the OBD I since it was built in Venezuela. None of my local parts stores have an OBD1 to borrow.

Temperature seems to have no bearing. The problem started in August and continues to now. We haven't really had a cold morning yet this season.

Thanks for the advice and linked thread. I'll try both.

 

[Tiha]

Plug wires, cap and rotor.

Common problem.

 

[Scott8]

I think I've figured it out. I crawled under the truck after turning the key and noticed the fuel pump "primes" for about 90 seconds to 2 minutes. I just waited or it to finish priming and it started right up. I did it again and it took about 20 seconds the second time. Then about 40 seconds the third time. But it started all three times.

I assume that means the fuel pump is going bad. But I wonder why it only does it in the mornings?

Also, it doesn't take gas at the gas station very well, so perhaps the little air vent is clogged. Could be related.

 

[ledzilla]

I was going to suggest the ignition coil, since I had an issue like that with the 5.0L in my Town Car that was fixed once I replaced the coil, but I can see you don't need that. I've never heard of a pump priming for so long, should only do that for a few seconds. Maybe you need to pull the pump assembly. The pick-up screen could be clogged. But your filling issue I've had with my '83. Yours has a different filler vent, but the same trouble can occur. Someone replace the vent tube in mine but didn't install it correctly, so it didn't vent at all. I brought it home on a really cold December day and I had to stand outside waiting for the tank to fill up extremely slowly. It takes a bit of elbow grease, but it isn't too tough to pull the filler tube out and inspect it. It's more difficult getting it reinstalled, at least in my experience.

 

[L\Bronco]

Ledzilla is right, they should only prime for 3 seconds on initial key on. Its a PCM controlled function.
I suspect leaking capacitors in your pcm. That would explain the high humidity failures as well.
I’d pull the pcm and pop the lid off. Do a thorough inspection, you can normally see the contamination on the board.
They can be replaced, if you have the skillset. Or you can source a reman PCM from Cardone or FS1.
Id inspect before making any decisions though.
That long prime, (plus erratic timing of it) point heavily at pcm failure though .
Good luck with it
Cheers

 

[Scott8]

I was going to suggest the ignition coil, since I had an issue like that with the 5.0L in my Town Car that was fixed once I replaced the coil, but I can see you don't need that. I've never heard of a pump priming for so long, should only do that for a few seconds. Maybe you need to pull the pump assembly. The pick-up screen could be clogged. But your filling issue I've had with my '83. Yours has a different filler vent, but the same trouble can occur. Someone replace the vent tube in mine but didn't install it correctly, so it didn't vent at all. I brought it home on a really cold December day and I had to stand outside waiting for the tank to fill up extremely slowly. It takes a bit of elbow grease, but it isn't too tough to pull the filler tube out and inspect it. It's more difficult getting it reinstalled, at least in my experience.

Thanks. I'll dig into the vent tube next weekend.

 

[Scott8]

Ledzilla is right, they should only prime for 3 seconds on initial key on. Its a PCM controlled function.
I suspect leaking capacitors in your pcm. That would explain the high humidity failures as well.
I’d pull the pcm and pop the lid off. Do a thorough inspection, you can normally see the contamination on the board.
They can be replaced, if you have the skillset. Or you can source a reman PCM from Cardone or FS1.
Id inspect before making any decisions though.
That long prime, (plus erratic timing of it) point heavily at pcm failure though .
Good luck with it
Cheers

Uhg. Thanks for the advice though. I'll look into that next weekend.

 

[L\Bronco]

Good luck! I hope Im wrong!
Cheers