Expert: A. Rowe - 12/18/2010

Question
i just replaced the fuel pump on my 99 GMC Sierra 1500 2WD 5.3L.  I am noticing two issues now:
1) the truck use to start on the first crank, but now it seems i need to prime the fuel pump by turning on the ignition for a few seconds and then cranking it so it will start.  
2) when i went to fill up the tank after replacing the fuel pump, the gas nozzel from the gas station pump seems to sense that the tank is full because the gas flow will cut off immediately after I insert the nozzel into my gas tank engage the trigger.  You know how when you're trying to top off the tank and the trigger compressses and no gas is flowing?

Please advise...thanks.

Answer
Hi Don!

You MAY have 2 different problems.

1) It's hard to say for sure without looking at it, but you may have to attach a fuel pressure gauge to see why it doesn't start right up. It may be possible that an internal line in the tank is leaking or is just a faulty pump. You wouldn't believe how many brand new electrical parts I get that are bad right out of the box! Can you hear the pump run if you just crank it? Is it possible that the fuel filter became clogged from dirt or whatever else in the tank getting unsettled and sucked in? Also, make sure that the 'vent hose' on top of the tank isn't pinched somewhere. It's easy to do while putting the tank back in on those trucks.

2) Considering that you just replaced the fuel pump, I'd check and make sure that the rubber hose on the filler neck didn't get twisted or something stuck in it while putting the gas tank back in. I've made some bonehead mistakes in the past. Especially late at night after a VERY long week/day such as having a gas tank down, stuffing a rag into it to keep 'junk' from falling into it. Then put it back into the vehicle without removing the rag. Or having a transmission mostly back into a car and then tripping over the torque converter. DOH! It happens time to time even with the best of us. haha


-----Aaron