How do I check the overflow valve at the outlet of the VP?

The reason I ask is because when I turn the key on, the fuel pressure spikes to 16 psi but slowly falls back to 0 psi before I start the truck. It also slowly drops to 0 psi after shutting the truck down. The pressure used to fall rapidly to 0 psi but not it's not.

Could the overflow valve be the problem?

Mark

 

You may not have a problem here and your overflow valve might be OK, depends on what you mean by "rapidly".

On my truck, when the engine is shut off, the fuel pressure drops from 12 psi to 0 psi in about 3 secs.

You can unscrew the overflow valve and look at the spring loaded ball inside, make sure it is seating properly and that the spring doesn't look broken or distorted.

 

george,

Hmmm...that's strange. What I mean by "rapidly" is it use to freefall to 0 psi after the key on. Now it's like yours and takes about 5 seconds to fall to 0 psi. What the heck? Maybe I'll check the ball and spring like you mentioned. Can't hurt. Thanks.

Mark