94 Jimmy, hesitation at hi speed

[GT55]

When first started it wants to run a little rough. As you drive at hi way speeds you can feel it hesitate (very slight). When you step on the gas at hi way speeds, you can really feel the hesitation. It will increase in speed but the hesitation sucks. The fuel pressure at the plenum when key is on (as pump runs) is about 57 psi. When pump stops, pressure immediately goes to 20 psi and stays there. Pulled off the manual vaule on top of plenum and looked inside plenum. No appearant signs of gas in plenum. Help>>>

Thanks

GT

[exalteduser]

if there is no washing inside, it could be "leaking down" in the gas tank. there are several ways to test for this, you could also do a search on it. There is a rubber hose from the pump to the sender that can leak, and a check valve.