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Pete, GMC Mechanic
Category: GMC
Satisfied Customers: 28793
Experience:  GM training and dealer tech for 14+ years. Diagnostics
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My 01' 8.1 starts in hot weather and easier in cold weather

Customer Question

My 01' 8.1 starts harder in hot weather and easier in cold weather making me believe that fuel pressure is droping because of a bad rubber component in holding the pressure at the rails?
Submitted: 1 year ago.
Category: GMC
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

Usually if it was a loss of fuel pressure it would start harder when cold and better when warm but still possibly a fuel issue.This may be an issue with the fuel pressure regulator leaking fuel into the vacuum hose that connects to it.On your fuel injector rail you will see the fuel pressure regulator and it has a vacuum hose attached to it.When warm remove this hose and see if fuel runs out.If it does then the fuel pressure regulator needs replaced.You may need to observe the regulator for several minutes to see if any fuel leaks out.

If this is o.k. this may be an issue with the check valve in the fuel pump itself with the check valve being faulty not holding fuel pressure.Install a fuel pressure test gauge onto the fuel rail test port and turn on the key,the pressure should rise and hold.If it starts to drop slowly or rapidly right away this can indicate the fuel pump needs replaced due to a weak check valve not maintaining pressure.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete