Mechanics

CHEVY HARD TO CRANK WHEN WARM

1996 Chevrolet Tahoe

Electrical problem
1996 Chevy Tahoe V8 Four Wheel Drive Automatic 234000 miles

it cranks very easy cold, b ut after it warms up and sits a while it hard to crank, but if you kill it, it will crankj up easy, like when cold, but let it sit a while it hard after it warms up!I have replaced the plugs & wires & new distributor complete with cap, rotor, cps, air filer, gas filter, I do not know wha the problem is!It misses intermittenly, could be bad gas, it was running better, the start problem warm, spins over, finally starts every time!
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Rlcrim
April 3, 2009.




Take the distributer module to a parts place that tests them. It is located beside the coil. I had one did exact same thing, finally left me stranded in parking lot.

Tiny
Jetlag
Apr 3, 2009.
Well, heres the deal, I went by auto zone, I took the module off, the tested it, they told me when it gets hot, its fails, well they told me it was okay, or checked out okay!I guess they could be wrong, I used to work at a dealer ship years ago before the electronic things came along, in the 70's, I not real familar with things, but the camshaft sensor was replaced when I replaced the distributor, I wondered if the crankshaft sensor, or the air sensor, throttle body, or injectors may need cleaning, but it cranks perfect when cold, like a new one, and when you kill it aqfte tyou run it a while or warms up, but if you let it set there for a while, it want hardly crank, kinda like a flooded carb on the older cars, so someone told me it could be vapor locking, or fuel pump weak, that doesnt sound right, one of the mechanic friend checked the ohms on the fuel pump, it was drawing 9.7 amps, he said usually anything under 12 amps needed replacing, but I not so sure about that, so here, so what do you think now?

Tiny
Rlcrim
Apr 3, 2009.
Im like you worked on my own cars in 60 s and 70 s but havnt keep up very well since electronic ignition came out, but I have learned some things. I know when you first shut an engine off the temp goes way up and thats when a module fails the most. They probable didnt test it enough to get that hot, I doubt it would get that hot on the tester. Advance has the cheapest price 69.00 where I live in Ga. I would buy an inexpensive spark tester and put on a plug wire next time it does it, I think you will have no spark or it will not be steady. When it not fires it does flood because injector keeps pumping gas. The car manuals they sell tells you how to check the sensers u mentioned with a volt ohm meter. There is a cold start function that could make it flood.

Tiny
Jetlag
Apr 3, 2009.
Well, after it warms up, it hard to crank like a flooded
carb, but it cranks the same way every time, spins over
several times, but it starts!I guess I can see if I can purchas the module and connect it after it gets warms with out mounting it, or using the heat sink
on back to see if this will fix the problem, then if not maybe they takeit back!O'Reilly usaully good about that, they say as long as it not mounted, dosen't say connected, well that way I can be sure at the time I get it, unplug it and connect and see if it cranks warm, the module want be warm, but engine, so what do yo think!

Tiny
Rlcrim
Apr 4, 2009.
Sounds like a plan, but be best not to spin it over first, it might flood before u connect new module. Also one of the connections is a ground but to be sure I would put a jumper wire with clips from mounting hole to ground. If it does same thing I would get a sprark tester and check, not the one with light but one from o riley where you can see it jump a gap, it should be blue spark that jumps almost 1/4 " gap. I am having same problem with my 96 tahoe but it wont start when cold. Not found problem yet. Mine is firing good.

Tiny
Jetlag
Apr 4, 2009.
Well, I found a control module at O'reilly, for $69.00, the cheapest one, I had already done what yuo said, jumper clips on module base ends to ground, so no mounting, or scratching on it, so if its not it, back it will go for credit!It looks maybe it might be the problem, I going to leave ot hooke dup a day or two to see for sure!Mine cranks like a new car in the morning, I hear the fuel pump up after key is turned on, and it firs right up and runs great!Youmay have bad gas, thta will certainly cause bad cranking cold, the crappy gas now days, well if you leave it in there very long, it induces mositure, the 10% ethonoil
they put in it after a few days yuo have normal sweating in tank, now the ethonoil induces moisture, so I only put half a tank in it, so I can keep fresh ga sin it at a station that use alot, or sells alot, so maybe they will have good gas on hand, tired of bad gas problems!If tjhis modulle works for sure, and cures problem, I let you know in a day or two, you might want tio check the air intake sensor in the flex intake air, I not sure what the name of it called, but it will cause running problems, so many sensors, and most mechanic don't know either, tge nice high dollar computer, you can see n=more things, but auto zone has alot of things it could be, but if you know what you have already done, well go to the other!Good luck with your problem!

Tiny
Rlcrim
Apr 4, 2009.
I hope that solves your problem. On mine I checked all the sensors that you can with a volt ohm meter according to manual. The one you mentioned is a mass air flow sensor and requires a code scanner to test. I have purchased one and am still reading on how to use the scanner. There is also a air temperture sensor in the flex pipe that can be checked will volt ohm meter. I found out on mine if I pour a small amount of gas on the throttle plate in the morn it fires right up. So moisture in gas might be some of problem.
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Tiny
Jetlag
Apr 4, 2009.
I found if the there is a leak in the flex hose to the
thottle body top, where it screws down tight, it will have ahard time cranking cold, warm!It sounds like either its not breathing through the flex line right, I mean, maybe a leak, and the sensor will cause it not run right, but maybe the thottle body flapper may not be closing all the way, or mositure in the gas like you say!It hartd to get rid of I call water in gas, when you get it, I don't put any morem in there until I run old all out and then use berryman liquid to put in tank to clean reat out and clean injectors, this bad gas will cause injector problem as you know, and it
may be off on it timing, has the distributor been removed or turned, that can cause problemsmbut can be reset with computer scanner resetting cam postioning sensor, I think this will put back in time, well I could tell you things you already know and tested, but as you know some scanners may read the problem and some want!Autozone scaner picked up I had problems possibly, but when they tested it it showed good, like I told you, he did not understand that, so I figure like you said it possible that one of your senor is going bad, cankshaft sensor, cam, who knows, have some ione else check it another place, maybe you can figur eit out with your scvanner, good luck, I thank you for your help, I going t drive it a day or two, and see it thisd really fixs it!I would be glad, not long ago when al, this mess started I had to replace intake gasket, water was getting in motor thiough a rear port, Gm has had problems with there gaskets set, well it been one thing after another, but its been a good car, even with the high miles, not long ago a oill change man letthe oil filter loose, it fall off and the engine shuyt off, so far it still running, okay, I had to flush out he engine mwith a quart of diesel, now my rear seal leaking alittle, oh well!

Tiny
Rlcrim
Apr 4, 2009.
Thanks for info, I had to put intake gasket on mine to. Took me a whole day. I was thinking if you drive around with module not fastened to the heat shrink it might get to hot but im not sure. It might be best not to connect it untill the next time that is usually when it is hard to start. If it starts right up you could connect the old one back up and see if hard to start again. I was getting ready to make donation but noticed you have made donation and no technition has helped u yet.

Tiny
Jetlag
Apr 4, 2009.
Well, I said I get back with you when io had a chance to check it out, it still has the problem cranking afte rit warms up, the module was not the proble, I took it back!I have been busy and sick, sorry it took so long!Got any more ideals!

Tiny
Rlcrim
Apr 9, 2009.

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