My fuel pressure has been between 58 and 62psi since I installed my Vortech on my 03 SilveradoSS. For the past week it's been going down to 38, and won't go past 55psi. These fluctuations happen at random times, at random throttle positions. I disconnected my inline fuel pump and the numbers didn't change much. They went a little lower than stated above. What pressure SHOULD I see just with the stock fuel pump running only? Are there any other ways to test my pumps to see which is not working correctly? It's looking the inline one is the faulty one. What do you think?
Thanks,
Mike

 

You should see the same fuel pressure from the stock pump as you do from the stock and inline combined. The only question is if the inline might block the flow if it is not running.

You should also check your filter. You may have gotten a bad tank of gas and plugged the filter up. The other thing to check is the fuel pressure regulator on the driver's side fuel rail. After you have had the truck out for a drive and with the engine off pull the vacuum line from the FPR and see if there is any fuel present. If there is the FPR will need to be replaced.

You should be able to hear the inline running. If you do check the filter and FPR. If they are good and the inline is running then check that the pump is getting 12Volts or better at the connection at the pump. Also take the ground off on both ends and clean the contacts to ensure that the ground is good.

Good luck sorting this out.

 

Mike, the first thing I would check is the Fuel Pressure Regulator as stated in the above post.

BTW, Welcome to the site.

 

i get like you said 50-65 psi with only a stock pump

 

Thanks for the replies guys. I can hear the inline pump running and it is getting 13.xx volts. I cleaned the grounds and checked the FPR. Everything seemed OK. I also changed the fuel filter. My pressure hasn't changed. What else should I check??

 

Take a piece of high pressure fuel line and bypass the inline pump and disconnect it. Your fuel pressure should be close to stock or about 53 @ idle, 58 @ part throttle, 62 or better at WOT and 50 or under on deceleration. If it is then it may mean your inline pump is weak but still working. If it is not then it would indicate that your intank pump is not up to snuff. Check that your intank pump is getting 12 volts or better of power and that the ground is good. Also see if you can check that the voltage is good when you are in motion and the pump is under load. The resistance in the pump may go up when it is under load but test fine at idle. I do hear about inline pump failures and it may be the culprit.

Also verify that your fuel pressure guage is good if eveything else appears to be working properly.

 

You might check the connector on top of the tank unit. There is a recall for the connector melting!! Causes just what you are talking about and sometimes worse, fires. I have tested my inline pump and intank pump the same way you have. I just disconnected my inline pump to see if the truck would still run and it did, pressure was unchanged but volume definatley was, but truck ran. Good luck!

 

I did all of the things except bypass the inline pump so far. I thought I had it fixed. I went to the track, and my times were good and pressure was mormal. I closely monitored the pressure on the way to the track and I was right on. Now last week problems started again. Sometimes everything looks good and sometimes I see 39 Lbs.
I'm going to bypass the inline pump after work today and see what happens. Thanks for the great info.
Mike

ALSO: To check the tank unit, do I have to pull the tank? I never messed with the intank pump.

 

All these pressure issues are starting to make me wonder about my pump.
Yesterday I drove my truck after it sat for two weeks, I had started it and let it idle in the drive a couple times but while drivig I saw as high as 75 psi just driving normally at 30-40 mph.
It started out at the normal 55-60 psi I usually see, but then rose to 75psi and stayed there the whole time I drove.
I know my year truck has a vacumn line going to the regulator could this be giving me some issues or other people who have fluctuations in line pressure?
What is the best solution for a failing regulator, which brand, and who sells them, or should you just replace it with a stocker again?I plan on changing the filter soon.
Hope you get your line pressures issues fixed SSmikeSS.

 

What is the performance like? What i mean is, are you feeling the truck fall on its face or anything? If not, maybe your fuel pressure sending unit is bad or the gauge is bad. Just saying this under the assumption you are NOT feeling any performance problems. I dont think i saw you mention any unless i missed it.