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Joe, RV Technician
Category: RV
Satisfied Customers: 815
Experience:  Associates Degree in Automotive Technology , 18+ years as RV and Commercial Bus Technician
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1988 pathfinder: sports coach GM chassis 454 manual fuel pump

Resolved Question:

I have an 1988 pathfinder by sports coach GM chassis 454 manual fuel pump. There is a valve on the frame rail next to the tank, with a 1/4' line on the top and a 5/8' line on the side. Its leaking fuel. What is it! A fuel pump regulator or some sort vapor valve?
Submitted: 5 years ago.
Category: RV
Expert:  Joe replied 5 years ago.
Hello , my name is Joe

Yes there should be a fuel regulator mounted on the frame near the tank. It regulates the fuel from the in-tank booster pump.

A replacement is available from Holly , part number 1135 .

Customer: replied 5 years ago.
I don't have an electric pump other wise there would be a leak when i turn on the key. The only pump is mounted to the block. I'm thinking its a vapor valve but i don't know.
Expert:  Joe replied 5 years ago.
All Chevy motorhome P30 series chassis built between 19851/2 - fuel injection have a booster pump in the tank. The pump is only supposed to run with the engine running , that is the purpose of the oil pressure switch and relay.

Here is a picture of a new Holly regulator

Customer: replied 5 years ago.
Joe i do not have fuel injection its a code W 7.4L 4bbl. My pump is mechanical on the eng block. I thought a regulator would be between that pump and the carb. I can take a picture of the Sevice Parts Identification Label, it might be of some help. I appreciate your patience in working with me.
Customer: replied 5 years ago.
Expert:  Joe replied 5 years ago.
Ok , perhaps I should try to clarify ; your motorhome has two fuel pumps , the mechanical pump on the block is limited to about 4 psi by design , the regulator on the frame is set at 4-5 psi pressure to feed the mechanical pump and eliminat vapor lock

Customer: replied 5 years ago.
Thanks for all your help i will get a regulator that is set to 4 to 5 lbs the holley # XXXXX is 1 to 4 . I'm looking at the holley # XXXXX But if you say the #1135 is what i need then i will get that one.
Expert:  Joe replied 5 years ago.
You should get the 1135 , it should be an exact replacement. anywhere in the 3-5 psi range should work well to feed the mechanical pump.

Joe and 7 other RV Specialists are ready to help you
Customer: replied 5 years ago.
No more questions at this point. I am going to get the part, and put it in so i can take it to the bathroom and relieve it. It does look like i will drop the tank a little to get to the dam thing. Thanks again Joe. Have a Great Day! Matt
Expert:  Joe replied 5 years ago.
Thank you , I hope all goes well !