'92 80 No Start after rain (1 Viewer)

Joined
Jan 7, 2019
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Alaska
Hey guys,

Looking for a little advice here. My 92 80 series with the 3fe and 240k runs great most of the time. However, recently I've found that after it rains, the truck will crank all day long, but not start. If I was driving it the day that it rained, it will usually fire right up again the next day, but if it just sat through the rain, I have to let it sit for a long while after the rain stops, but then it will fire right up and run without hesitation.

In the preliminary stages of figuring this out, so I thought I would ask which tree I should start barking up before I dig in hard because I'm working on it outside and it's still cold and wet up here in Alaska, so the weather windows for me to work on it are limited.

Here's my thought process/what I've found so far:
Checked under the hood. Found that the gasket at the back of the hood towards the windshield was dangling so I reseated that, but nothing under the hood looked especially wet. Checked again this morning after a hard rain, and it's pretty dry under there. I also found a slow leak in the lower corner of the driver's side of the windshield. I removed the kick panel and inspected all of the fuses and control boxes — none of them showed any evidence of being wet, nor did I see any water in the area. It looks like it's getting diverted toward the firewall. Is there something else under there that would cause a crank, but no-start if it got wet that's not in the kick panel?

When this first started happening, before I realized it only happened after rain, I took it to my mechanic and had him check the fuel pressure, thinking I had a delivery problem. He said the truck was in spec and delivering fuel just fine.

When the truck is running, it doesn't have any CEL on, but on accessory power, the CEL shows solid like it should. I believe this rules out the EFI relay, but correct me if I'm wrong.

I recently replaced an O2 sensor. Is it possible that getting those connections wet would cause this? I was leaning to no, since once the truck starts up there's no CEL and it drives through puddles and rain all day without issue once it starts.

I was thinking I should replace the FPR, to rule that out. From everything I've read, a bad one would cause this condition, and maybe the rain is just a coincidence.

I haven't opened up the dizzy yet to inspect it. Like I said, there was no evidence of water intrusion, and also, if it was moisture in there causing this, wouldn't the problem manifest itself while driving in the rain? Not ruling it out, that's just what I was thinking initially. I'll check this soon.

Haven't checked for spark during the no-start condition. Will do that next. If I don't find spark off of the distributer wire, is it likely that the coil is going bad and the moisture exxaggerates the problem?

That's all I have so far, and thanks for any feedback. Hope I've given enough information to start to narrow it down a bit.
 
Joined
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Thoughts:
While siting, the windshield seal leaks. Drips on the ECU. Kills the ECU.
ECU Dries out, runs fine.
Doesn't leak when driving because the blower fan pressurizes the cabin and the windshield doesn't leak and drip on the ECU.

There have been a few threads like this, but I think they were more about the HVAC controls under the dash, but it's a possibility. Having rain get on the electronics that are under a giant slab of metal seems unlikely unless there is severe windblown rain.
 
Joined
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Alaska
Thanks for the feedback. In the 91-92, is the ECU under the driver's kick panel, or is it above glove box like in the later models?
 
Joined
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New Jersey
When the truck is running, it doesn't have any CEL on, but on accessory power, the CEL shows solid like it should. I believe this rules out the EFI relay, but correct me if I'm wrong.
You need to elaborate on the above statement. In a no-start condition when the problem surfaces, is the CEL illuminated with the key in the ON/RUN position?
 
Joined
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You need to elaborate on the above statement. In a no-start condition when the problem surfaces, is the CEL illuminated with the key in the ON/RUN position?

CEL is illuminated in the ON/RUN position. Sorry. Accessory wasn't very accurate.
 
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The circuit opening relay is behind the driver's kick panel. It feeds the fuel pump. It might be getting wet from a windshield leak.
Good Luck!
 
Joined
Jan 7, 2019
Messages
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Location
Alaska
The circuit opening relay is behind the driver's kick panel. It feeds the fuel pump. It might be getting wet from a windshield leak.
Good Luck!
Killer. I'll check that out today. I tried to access Jonheld's no-start worksheet that was posted in several of the other threads, but it takes me to a server error page, so I'm assuming the file is gone.
 
Joined
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If the CEL is illuminated, then the ECU is in a "ready" state. You can eliminate the ECU at this point.
When was the last time the distributor cap and rotor were changed?
How old are the plug wires?
You need to check for spark and fuel when the next no-start occurs.
If you slightly crack the cold start injector banjo fitting, fuel should come out during starter cranking. If you have fuel, then move on to spark.
Don't overcomplicate this engine. It is a fuel injected tractor motor in its most basic form.
 
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Well, that was anticlimactic. I knew I shouldn't have focused on this seemingly being a rain issue, because it wasn't, that was just coincidence.

I popped the distributer cap after confirming that I was getting fuel, and while it was dry as a bone in there, the rotor was a mess. New rotor and new plugs (waiting now on a new cap and wires), and the ole girl fired right up. Now it runs better than it ever has.

That's what I get for trying to tie things together off of suspicion rather than facts. Oh well.
 
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Joined
Nov 9, 2012
Messages
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Olathe, KS, USA
Well, that was anticlimactic. I knew I shouldn't have focused on this seemingly being a rain issue, because it wasn't, that was just coincidence.

I popped the distributer cap after confirming that I was getting fuel, and while it was dry as a bone in there, the rotor was a mess. New rotor and new plugs (waiting now on a new cap and wires), and the ole girl fired right up. Now it runs better than it ever has.

That's what I get for trying to tie things together off of suspicion rather than facts. Oh well.
Thanks for coming back and letting us know.

We all use this as trouble shooting and it helps everyone when the follow up is done.

Congrats on figuring it out!

Toyota parts?
 

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