GMC 1500 Express won't stat when cold

[CrestaMan]

Hi

I have recently purchased a 1998 Chevy/GMC 1500 Express dayvan. It has the 5litre vortex V8 engine. The van was a non runner when I got it and would not start. I have renewed the sparkplugs and ignition coil still nothing. as a last resort I poured some petrol down the air intake and she fired up on the key and runs real good. It will start again whilst still warm but not from cold without a squirt in the air intake. Whilst cold the van has little power but improves when warm. Is this a problem with a sensor making the ECU think the engine is always warm and hence not "choking" the engine for a normal cold start?

Regards

CrestaMan

[Guest mercman86]

I have seen this before. A failed Manifold Air Temp sensor (MAT) and/or a coolant temperature sensor could be the culprit. Is the check engine light on?

Hope this helps!

[Larry Schramm]

Do you have a tech 2 scanner to check the readings of the temp sensors(or a scanner that can read the values of the sensors in real time?). The most likely cause would be the engine coolant temp sensor. The computer will not set the light if the sensor is between I think -40F and about 275F because that could be the operating temp. If you can get a scanner, check the readings of the two sensors before you start the engine MAT & ECT and they should be about the same. +_ 1 or 2 degrees. Replace the one that does not match the outside temp.

[CrestaMan]

I'll borrow one on Monday and see what it says. I'll let you know how I get on.

[rick60]

Be sure to check your fuel pressure. A restricted fuel filter will cause a "no start cold" condition. If your fuel pump is loud when the engine is running it is most likely a restricted fuel filter. The pump could also be defective. Make sure it is at factory specs. A little below specs will not start the vehicle. It will run with low pressure after you get it warmed up. I'm a former Chevy mechanic. When I was dispatched a "tow in, no start" I would check the fuel pressure. If it was below specs I'd start the vehicle with a shot of carb cleaner and then drive it into my bay for the repair. It was easier than pushing work vans up hill. Good luck.