Formula413

iTrader: (1)

Lately I've noticed that sometimes when I turn the car on and listen for the fuel pump to prime that instead of running for a few seconds and shutting off like it normally would it runs for about 30 seconds to a minute. Has anyone ever seen this issue before? I tried searching but apparently I am the only person ever to have this happen. Car is fine otherwise, no codes for evap leaks or any evidence of a problem with the fuel system. Thanks in advance for any info.

Formula413

iTrader: (1)

Bumpitty bump...

No one has seen this before?

camaroguy26

iTrader: (21)

never seen it before but seems like you've got a problem. Start checking for fuel pressure at the rails, you might have a blocked line or clogged fuel filter causing it to not prime like normal. How many miles are on your filter? You might want to just change that out and see what happens. If all of that seems normal your pump may be going out, not pushing fuel like it should, hope this helps some but I dunno what else to tell ya

Formula413

iTrader: (1)

That sounds like a good place to start anyway. For all I know the fuel filter is original (bought the car with 73k miles) so it should be done anyway. I'll probabaly pick up a pressure guage too. It just seems like if I had a clogged filter/leak/bad injector or something like that there would be other issues. It runs great.

Does anyone know what determines how long the fuel pump runs when priming? Is it a preset amount of time, or does it run until it acheives a certain pressure?

2002_Z28_Six_Speed

iTrader: (19)

It is not determined by pressure.

Have you unplugged the engine coolant temp sensor?

Formula413

iTrader: (1)

No, as far as I know the ECT is fine, I usually have a guage pod hooked up and it reads normally. How would that affect the fuel pump?

2002_Z28_Six_Speed

iTrader: (19)

The PCM will inject more or less fuel based on ECT. PCM should have no way of knowing how much fuel actually got there. hmm.

Tried a different relay? Maybe yours is sticking.

Formula413

iTrader: (1)

That's a good idea, I'll give it a shot. Thanks for the ideas guys, if anyone else has any thoughts post 'em up.

Z28_DAD

iTrader: (18)

beat me to it.
pump has a 2 second prime, turns off till it sees cranking rpm, then activates the pump till you shut the car off

Formula413

iTrader: (1)

Update: It's not the relay. Tried a new one and it still does it. I also pulled it off and checked for voltage at the connector and sure enough it is being supplied with voltage when this happens. When it does this it seems to run for exactly 30 seconds, instead of 2. I was able to get it to do this several times in a row when I had the relay off and the voltmeter on the connector. Then when I put the relay back on it went back to normal. I can't find a variable that affects when this happens. It seems slightly more likely to happen when it's cold. The fact that it runs for exactly the same amount of time makes me wonder if this is something the computer does for some reason.

Edit: Another update, it's not the filter either, I changed that and it still does it. I guess this is just going to have to remain a mystery.