Could really use some help on this one!

2001 DAK, 4.7L, auto. When outside temperature drops enough to use the heater, and I've driven long enough for the cabin to be warmed up, if I pull in somewhere and shut the truck off, it won't restart. Dash lights come on normally, chime goes off, but engine does not crank.

After sitting for 40 - 60 minutes, it fires right up.

I can drive around all day and not experience restart problems if I don't use the heater.

I've also experienced the problem if the truck has been sitting all day in direct sunlight (during the colder months). Won't crank until it's been out of direct sunlight for an hour or so.

There are never any codes. Disconnecting the negative battery cable to reset everything has no effect.

I figured it was some heat sensitive electrical component or box inside the cabin that is failing. But the fact that this also happens after it sits in the sun for awhile seems to contradict that theory. Again, this only happens during the winter months. The cabin temperature during the summer months is surely warmer than it gets under these conditions, and it does not have starting problems then. This is in Washington state. Mostly rainy and mildly cold during the winter. Any suggestions?

 

are you hearing the fuel pump turn on when you turn the key?

where in WA are you from. Im originally from seattle.

 

Nope, don't hear the pump. Would it be easy to hear from the cabin? Maybe I am just not noticing the noise.

I'm north of Seattle up in Everett.

 

you should hear it in the cab. just open the door and stick ur head out. and turn the key to the ON position, and cycle back and forth. if you dont hear a buzzing noise for a few seconds they most likley its ur pump. get a fuel pressure test kit and see what the psi of the pump is. if you dont know how to do that just ask.

 

Cool, I'll give that a shot and post back.

So you moved from Seattle to Kansas? I used to live in Cheney, near Wichita.

 

haha bizzare. yeah i miss seattle greatly, kansas= not my fav. place. but its only for school. when you just prime the fuel pump psi should read 47ish. if you get it started idle should be between 45-49ish.

 

I have not tested fuel pump PSI yet, as I don't have a pressure gauge. I know I can pick up a kit for around $50. In the meantime, I managed to do some testing, both when the truck starts, and when it won't.

The fuel pump does kick in when I turn the ignition to start. The fuel pump relay is working. What I've found is that the starter relay does not get 12V to terminal 86 when it won't start. So something else that should enable that 12V signal is not happening. The ignition switch is working, and the transmission range sensor seems to be operating normally per the factory service manual test procedure, which has you disconnect the battery, them pull all 3 PCM connectors and measure resistance between C1 pin 6 and ground as gear shift lever is moved through all positions.

Based on all that, so you still think the fuel pump is suspect? I appreciate your help.

 

you wont know for certain untill you test it properly.

 

After going over the starting system wiring diagrams, I just couldn't see anything other than the ignition switch and wiring that comes into play to put 12V to that starter relay. I made a $25 gamble and replaced the switch. It fired right up after that. Time will tell if that was truly the problem. I'll post my success or further pleas for help regardless. Intermittent problems are SO much fun.

Thunder - minor correction to my previous post. I meant to say do you think... not so you think... in that last sentence. A bit of a nuance, but in re-reading my post, I thought it sounded kind of challenging instead of questioning, which was not the intent. Your advice is much appreciated.

What are you studying in Kansas?

 

well if its running fine now just think to your self its fixed, untill it doesn't start then start to attack the problem again. but just to be sure i would still check the FP. although one day they work and the next they are dead.

im going to k-state, studying park mgmt. and conservation. i want to work back in WA, maybe near Forks in a fish hatchery or forresry type job.