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Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 1685
Experience:  GM Grand Master Technician 2007. 14 year experience.
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My truck starts first time when its cold, but after it heats

Customer Question

My truck starts first time when its cold, but after it heats up it is hard to start. It will sometimes do a surge at a stop lite & the idle will drop down till it either dies out or picks back up. One shop said the idle needed to be turned up ,but it didn`t help. I have a `99 GMC SIERRA SLE with a small V8 with 104000 mi.
Submitted: 1 year ago.
Category: GMC
Expert:  Tim Mohr replied 1 year ago.

Hi, my name is ***** ***** motor do you have in this?

Customer: replied 1 year ago.
small 8
Expert:  Tim Mohr replied 1 year ago.

ok, and it only starts hard when its warmed up, and also only surges when its warm?

Customer: replied 1 year ago.
Expert:  Tim Mohr replied 1 year ago.

These are common symptoms for a weak fuel pump, and we see this alot, did the mechanic check the fuel pressure when its warm?

Customer: replied 1 year ago.
he left it idling while there & it surged then died out.
Expert:  Tim Mohr replied 1 year ago.

and what was the fuel pressure when it was dying out?

Customer: replied 1 year ago.
I don`t know other than he said it was good
Expert:  Tim Mohr replied 1 year ago.

it needs to be above 60 psi, if it drops any lower, this will happen, I need to know what th exact pressure was, can you call him?

Customer: replied 1 year ago.
no, he`s at work & unable to receive calls
Expert:  Tim Mohr replied 1 year ago.

we see this alot, it is most likely a weak fuel pump, how many miles do you have on this?

Customer: replied 1 year ago.
104000. the fuel pump was replaced 2 years ago
Expert:  Tim Mohr replied 1 year ago.

does the check engine light ever come on when driving?

Customer: replied 1 year ago.
it use to, but doesn`t do it anymore. The shop couldn`t get a reading with the dian. test but was told they fixed it & was told it was why the lite came on .
Expert:  Tim Mohr replied 1 year ago.

ok, first off, does the check engine come on, when you first turn the key to run, and then go out after running for 2 seconds?

Customer: replied 1 year ago.
are you still there?
Expert:  Tim Mohr replied 1 year ago.

Yes, I am still here, does the check engine light come on for 2 seconds when starting, and go out?