Garon

Hi All,

My 2000 Silverado (V8, 4.8L) with 135,000 miles is having a starting issue. If the truck has been sitting for >20 minutes, it cranks for 3-4 seconds before starting. However, if you turn it off, and then start it right nack up, it cranks over / starts immediately.

It does this whether I have a full or near empty tank, and the only time I have noticed it not happening (as much) is when I start it first thing in the morning when the outside temp is 50 degrees F or below.

I have a new fuel pressure regulator, have cleaned the throttle body / fuel injectors, and have a clean fuel filter.

I have not measured the fuel pressure (do not have the tool), but I am not sure if this is consistent with a fuel pump beginning to go out.

Any troubleshooting help would be greatly appreciated.

kevinkpk

I'd suggest this, turn on the key without starting it, wait a few seconds, then start it. If it starts right up, it would appear to me the fuel pressure is "bleeding" down.

Garon

If the fuel pressure is 'bleeding down', and there is no leak in the fuel pressure regulator vacuum hose (to the intake manifold), does that mean there is an issue with the fuel pump? If this is the issue, is there a check valve in the fuel pump that should not allow gasoline to drain back into the tank?

kevinkpk

Well, could be a purge valve solenoid leaking back to tank

Garon

I performed the check you requested and the results are the same: If the engine has been recently started (less than 20 minutes), it will crank right up. If the engine has been sitting a while (such as overnight), it takes several seconds of cranking before it turns over.

Thanks for the replies. Any thing else you can think of?

MDTAHOE

Yes there is a one way valve built into the pump assembly to keep the fuel from bleeding back into the tank through the pump. Cycle the key atleast 3 times on 3 seconds off 10 then try to start it. If it starts right up and there is no gas in the regulator line then you need to replace the pump assembly.

Garon

MDTAHOE-

It does appear that cycling the fuel pump 3-4 times before a start has helped tremendously. I did it after work yesterday (sitting for 9 hours) and this morning (sitting for 10 hours) and it cranked over in the regular 1-2 seconds. Assuming I need a new fuel pump, which I will order new, do you recommend also replacing the fuel sending unit (which I assume must be ordered separately)? Does the discussed check valve come with the pump module when ordered? Is there anything else you recommend changing while the fuel tank has been lowered from the vehicle?

Thank you for your knowledge and replies.

MDTAHOE

The fuel pump should come complete sending unit and all. Only buy Ac Delco or Delphi brand anything else has a extremly high failure rate (in less than 1 year).

Garon

Thanks agaion MDTAHOE. I would love to tackle the fuel pump assembly replacement myself. How difficult for a weekend mechanic do you think this would be? I have done all the basic maitenance myself, and usually left the more involved jobs to the professionals.

I have read the Haynes manual (with photos), and it seems to be farily straight forward. The hardest part appears to be lowering the fuel tank. Do you think it would be possible to do this in my driveway?

MDTAHOE

If the tank is empty you could do it in your driveway, it will not be fun. You need to have a jack to lower the tank with. Lots of people on the forum have removed the bed to do the job.