Starting problems

[frank07]

Hello all. I have been having problems with my truck for about the past year and a bit. I have a 1996 Chevrolet 1500 pickup, extended cab, long box, automatic, 5.7L, 2wd. The problem I have been having, is that in moist/wet weather, the truck will not start. It will crank, but will not turn over. Last year, I got the spark plugs, distributor cap and ignition coils replaced. Worked for a very short period, then same thing happend. Then about a month ago, I brought it back to the garage I usually go to. The mechanic told me to bring my other truck to the garage, which is a 1997 GMC 1500 Pickup, automatic, 5.3L, 2wd, and works perfectly fine, no problems. He wanted me to bring it there so he could swap sensors and such things from truck to truck to see if he could find out what sensor was causing the problem. He worked on it and could not find the problem. I go to pick up the trucks, and this time the '96 started fine (weather was fine outside), and at a later date came to pickup the '97 pickup, but the '97 would not start. So the mechanic thought if there was any sensors he did not swap back, and he remembered he did not swap the MAP sensor back because he did not think it had anything to do with the problem. So he ordered a new MAP sensor for the '97, started up fine, everything was good.....until today. The '96 is not starting again, so I'm thinking it was not the MAP sensor. It was spitting rain today, so it still must have to be with the weather being wet. The '96 hadn't been driven to 2 days. I tried jumping it, but nothing. The truck cranks, but does not turn over, and at some points while trying to start it, shakes from side to side.

 

I do not know if this has to do with it as well, but after being at a red light, when I accelerate slightly, the engine revs, and then the wheels kick in and it kind of "jolts". And then when switching from 1st to 2nd, it runs high rpms, then jolts again, and same from 2nd to 3rd, it gets quite annoying, it does this all the time.

 

If anyone has had the same experience or knows of what the problem could be, help me out, this is driving me crazy!!

 

Thanks,

 

Frank

[GM-Tech]

First of all, lets get some terminology straightened out. This has always been a problem in the service drive here when the writer doesn't get the information correct due to people's usage of these terms. If it's an intermittent problem, it can end up being misdiagnosed or not diagnosed at all due to the mechanic thinking it's doing one thing when it's really another.

 

"crank" and "turn over" is the same thing. So you can't say it cranks but doesn't turn over. It's contradictory. If it cranks, it's turning over. It may not be starting, and therefore running, but it is definitely rotating/cranking/turning (over). I always have a real hard time getting customers to understand this concept and have been sorely temped to record the sound of an engine "cranking" but not starting so they could listen and tell if that's what it's doing.

 

Ok, off the soapbox. The second problem you listed sure sounds trans related. Fluid level okay?

 

Back to problem #1. Has anyone checked fuel pressure? If so, what was it? "Good" does not count, we need actual pressures. However, I don't see what this would have to do with rain and would look more to distributor in that case.

[frank07]

ok well it sounds as if it will start, but it doesnt. are u familiar with such a problem? also, after finally getting it started, the gay runs really rich

[frank07]

help people.

 

GM-Tech, sorry for my misuse of words, have u heard of such a problem?

[jedcooper]

I've heard of hard starting around that year of truck being the fuel pump on its last leg. I'd go with the professional here and get the fuel pressure checked.

 

Maybe low pressure and just too lean a mixture when cold and wet out.

[95Sierra2500]

Get the fuel pressure checked, and also check your plug wires for cracks. Since it sounds like it's related to moisture, something is shorting out in your ignition system.