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Fuel return line

Jasonsupafly

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Jasonsupafly Enthusiast

Jasonsupafly

Posted
Posted

Need to do a pressure test on fuel system. Can anyone tell me the procedure for blocking off the return line and checking the pressure? Is it something easy to do?

 

2001 Silverado 5.3

155k miles

 

Thanks!

8.1HD/ALLISON Senior Enthusiast

8.1HD/ALLISON

Posted
Posted

They make a fuel test kit we had at the shop. You disconnect the return side and install adapter with a shut off in it. Fuel pressure regulator is bad if you can so much as smell fuel when you remove the vacuum hose. With engine running and remove vacuum hose fuel pressure should go up slightly. 4 or 5 psi maybe at most?

jBlaze3000 Enthusiast

jBlaze3000

Posted
Posted

I was told by a couple of people that it's a good test to determine a faulty pressure regulator. Keep in mind I stated thats what I was "told"...

 

 

I'm no expert by any means but I had never heard of such a thing so I was curious. I was able to troubleshoot a faulty pressure regulator on my wifes car with just the gauge. Pressure would jump to normal range then immediately drop back down to zero.

Jasonsupafly Enthusiast

Jasonsupafly

Posted
  • Author
Posted

Im not either man. Im having a hard start issue after sitting for a while. My pressure gauge drops slowly to nothing after I turn the key off. It doesnt hold. If i crank it with the gauge on and give it throttle the pressure drops a good bit then rises back when I let off the pedal. Seems everyone I talk to has something different to say. Some say regulator and the other half says fuel pump. My sending unit has been jumping for a couple of years so I know thats part of the pump assembly. Hate to replace the pump if its just the regulator or vise versa.

8.1HD/ALLISON Senior Enthusiast

8.1HD/ALLISON

Posted
Posted

If you are going to test the pump with the return side shut off, you are going to " dead head" the pump. That will show you if you have a weak pump. We used to do that all the time at the shop. I don't remember what pressure should be. Also it gives you the abitlity to shut off return side of fuel system. If you have return side shut off and pressure still drops, with no external leaks, you have a check valve not working in the pump and you have to replace the whole pump.

Jasonsupafly Enthusiast

Jasonsupafly

Posted
  • Author
Posted

Im just going to replace the pump. Only thing holding me back is where to get it from. A couple of places on ebay has them for around 170.00 shipped. Delphi and AC Delco brand but im scared they may be knockoffs although both sellers have thousands of sells and great customer feedback. The next option is Rock Auto but they are arounf 250.00 from there. Sure would like to save the money but like I said I dont want a cheap part and have problems a few months down the road..From what I can tell everyone is saying to stay with AC Delco or Delphi and to stay away from Airtex pumps...Any suggestions to help me make a decision?

 

My other question is knowing if I need the pump with the EVAP emission plug or the one without. One has a single plug and the other has 2 plugs on the top of the pump. I cant tell how many connections I have taking that I cant see the top of the gas tank.

jBlaze3000 Enthusiast

jBlaze3000

Posted
Posted

Take a look at my "Buying parts on Amazon.com" thread. I'm going through the same thing as you and opted to get a Delphi pump from Rock Auto. Amazon had an AC Delco pump for $110 cheaper than Rock but it just sounded a little too good to be true. I figured that if I was going to gamble I'd just buy an Airtex. The fuel pump is one part I'm not willing to take chances with.

jBlaze3000 Enthusiast

jBlaze3000

Posted
Posted

There was nothing mentioned about that for my vehicle. I just looked at the fuel pumps listed for your vehicle and wow, there are a lot of notes about checking the model ID tag and connectors and stuff. Wish I had some advice for you (outside of dropping the tank and looking at your current pump). VIN number maybe?

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