Hard to start

[zsnowman]

I have a 2002 GMC 1500 with a 4.8, 186K miles. My truck is hard to start after it sits for more than 15 min, to include over night, engine temp does not make a difference.

To start it takes three or four attempts with a few seconds pause in between.

To start it, I start for second or two like you normally would, release the key leavening it in the run position, letting the fuel pump run. I have to do this three or four times. When it starts it stumbles for a few seconds, and then runs great until it sits again. I have tried letting the fuel pump run for 8 seconds first, this does not make a difference.

About two years ago I replaced the fuel pump with an after market one. In the past two months I have replace the fuel filter, air filter, cleaned the throttle body, replaced the fuel pressure regulator and replaced the plugs with AC Delco from the dealer.

 

Thanks for any help, Bill

[DeePa]

hook up a fuel pressure guage to the fuel rail and see what you get at key on, then when it finally starts and runs...

 

I know that the fuel pump only runs for a few seconds to build pressure. You could try key on/off a few times before actually starting, which would cycle the fuel pump a few more times...

 

Mike

[8.1HD/ALLISON]

+1 on above. If I remember correctly, you should see about 62 psi fuel pressure. From the sound of it I would say your fuel pump is getting weak. IMO I never go with aftermarket fuel pumps, Saw your problem way too many times at the dealership.

[z71MudDog]

might be the cold start sensor. the cold start sensor enrichs the fuel mixture to help it start more easier.its OBD II get er scanned maybe you'll find something

[zsnowman]

Thanks, I will try the fuel press check. I need to get a tester first. I do not have a fuel press tester.

Are the ones discount auto parts stores sell any good? I scaned for codes, does not have any.

[z71MudDog]

well that narrows it down to a fuel issue you could get a good tester use it then take it back...

[kwed2011]

i have a similar problem with my 2000 Silverado 5.3L. I put a pressure gauge on the fuel rail & noticed it takes a couple of key turns to get the pressure up to the 60PSI range after truck has been sitting more than 1/2 hour after running. Cold starts are always easy in my case. One thing I noticed during the pressure check is that the pressure drops to zero in a few seconds after the engine is turned off. Isn't there a check valve that holds the pressure longer than that? My only other experience testing fuel pressure is on my fuel injected 76 Seville. On it, the fuel rail holds pressure for several minutes after the engine is turned off

[txab]

It should hold pressure.Time for a replacement

 

Edit to add:

 

On a 2000 model, check your fuel pressure regulator at the vacuum line for the presence of fuel

 

After you do the key on, engine off pressure test, pressure should stabilize. If it drops more than 5 psi after 1 minute, then check the FPR

 

After that it's the pump

[brainpause]

It should hold pressure.Time for a replacement

 

 

Just for my own understanding, what should hold the pressure? A check valve? The fuel pump? A check valve in the fuel pump?

[Jim L]

I had the sme problem on my 96 chevy and it was the fuel pump.