Been having a little problem with my 92. On cold days, like 10 or below (rough estimate) it won't start. Turns over fine but won't start. The fuel pump continuously runs, doesn't do it's normal prime cycle. Then when the temp gets warmer, it fires right up and everything, even the fuel pump acts normal. I haven't been able to scan it when it's doing this, but it has me thinking that the cold is messing with the computer. When I first got it the computer was bad and causing it not to run so we just through a salvage yard one in. My F250 we did the same thing, but the F250 also had the trans in limp mode, and the F250 would run sometimes although it would misfire and blow black smoke. So I'm decently familiar with how they act with a bad computer.
I took my scanner home from work today to scan it just in case it wouldn't start. It fired right up, being as that it was 39 today and not -2 like it was the other day when I tried to start it. But, I scanned it when it was cold and got codes for ECT, IAT, and TOT codes which I figured I would since it was cold. I let it warm up a bit then took it for a drive to let the trans fully warm up. Got back to my house and scanned it again, no codes at all. So I'm stumped. Anybody ever have similar issues and if so what was your fix?

Also, I noticed in data mode that the IAT was reading 140 degrees. Does that seem right? I knew it would read higher than outside temps since underhood temps are a lot warmer, but I didn't think it would read that much. Also ECT was reading 186 when I scanned it so I highly doubt the ECT is to blame. And I can't see either the IAT or ECT somehow causing the fuel pump to run continuously.

 

BTW this is on my Bronco. I figured I would post it here in the F150 forum since it has more traffic and is the same fuel injection set up. If that's not okay I can always repost it to the Bronco forum or a moderator could move it for me?

And another thing, last week it was about 20 degrees out and I went to warm the Bronco up. It fired right up and I let it warm up for maybe 10 minutes at the most. But I went to drive off, trans was in limp mode. Engine was also misfiring and popping out of the exhaust and intake. I pulled off on the side of the road, turned they key off then started it back up and engine ran as smooth as could be and trans was no longer in limp mode. And those characteristics were similar to how my F250 would act when I first got it. I'm confused because it's never acted like this before (except when I first bought it with the comp. problem), it's only when the temperature outside is really cold.

 

Anytime the fuel pump runs continuously when cycling the key from Off to Run it's either a stuck relay or the PCM is bad. The latter is the most likely culprit and would explain why the truck will not start, it also controls spark.

 

I just don't understand how the cold weather has any effect on the computer. though. It just baffles me. But it really seems like that is the only issue at hand

 

Just a Thought, But Maybe your fuel is freezing up and not properly shooting to your engine as Fast... or AT ALL... In my Humble Opinion...

 

I Agree, I don't think it's the computer either....

 

Well the only thing that could cause the fuel pump to run constantly is the relay or comp. like RLA said. I know the continuous run cycle and no start issue is related, has to be. I'm going to bring my noid light set home with me from now on and if this issue arises again, I'll be able to see if my injectors are pulsing. If they aren't being sent the pulse signal from the comp and the pump is running constantly, I'll know for sure it's the computer.

 

My '73 Beetle wouldn't start in really cold weather. It was an electrical connection that wasn't being made due to contraction

 

If you don't mind me asking, what scanner are you using? I own a Craftsman OBD 2 scanner w/live data ability and also ability to scan/pull codes from older OBD1 systems. To my knowledge, my Craftsman scanner/reader cannot read live data from OBD1 systems.

 

Bingo, Derek.

I had a Chevy van that needed a propane torch to start when it got below zero. I'd be underneath the van heating the starter for 30 seconds with the torch then trying the key until it started. I also failed a mobile transmit antenna because its return loss went to zero at 40 degrees Fahrenheit or less, while it was an easy 25 dB from 41 degrees up. When I took the antenna apart I found out that one of the solder joints on the coil was broken and barely connected -- and when it got cool (not even really cold) the wire contracted far enough to break the connection, meaning that instead of being radiated from the antenna all of the power bounced back to the transmitter.

If you can get an illuminated magnifier you can examine the solder on the connector as well as the solder on the chips for any cracks. If you find any, see if your local JuCo has an instructor that would be willing to flux and reflow the bad solder joints for a couple of bucks.

 

Solus Ultra

 

^^^ I have one too and LOVE it! I just need OBDI connectors and the Euro package to make it complete

I do agree that IAT looks high, however if the truck was sitting after being run there could be some heat soak in the manifold from no airflow or coolant circulation. The continuous fuel pump running raises a red flag as mentioned, I would investigate that. The injectors could very well be firing, however no signal is sent to the ignition system.

 

I hate it. Only thing it has going for it is touch screen.

 

The shop owns an old OTC Genisys, which I don't care for. Another tech got a Verdict, that thing is awesome.

 

We used to have a Modis. Now that was a sweet scanner before it got stolen. I hated having to install those damn keys in it though.