A second opinion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Troy Campbell · 07-13-2008, 02:00 PM

I was driving home from a car show yesterday, my 71 chevy p/u started loosing power. I have a 402 BB , with a Elderbrock 600 cfm. The fuel pressure regulator gauge said 2 psi, I have it set on 6 psi. I increased the rpm, the fuel pressure went to 1 and my glass fuel filter went empty. I believe my fuel pump is weak and going out. Does that sound like a fuel pump to yall?

Willys47 · 07-13-2008, 02:14 PM

was the gas tank empty? maybe vapor locked line?

Troy Campbell · 07-13-2008, 02:22 PM

The fuel tank was 1/2 full, I thought it was vapor locking at first, but when I finally got it home and let it cool down, it done the same thing again. When you acc, the fuel pressure gauge goes almost to 0 and the glass fuel filter goes almost empty. It has a mech fuel pump on it.

**steelhorse** · 07-13-2008, 02:22 PM

Fuel pump/out of gas/is the cap vented possible causing a vacumn on the tank?

Troy Campbell · 07-13-2008, 02:28 PM

The truck had gas, the cap is the same one since 1971. I wonder should i start it with out the gas cap and check my fuel pressure?

**fine69** · 07-13-2008, 02:47 PM

Take the fuel line off the pump. Blow back through it. See if its clogged up.

dwcsr · 07-13-2008, 03:06 PM

I had the same issue on a 77 with dual tanks. I never did find out what it was but I had replaced everything from the line on the frame forward and used an electric pump. I suspected it was a clogged pickup or a rotted rubber line out for the tank or possibly both. It would start out a 7 and go on a 2 mile run and be down to 2-3 or less.

**Boog** · 07-13-2008, 03:17 PM

The strainer in the tank may be stopped up. Also do you have a filter between the tank and the pump? Pull the oil dip stick. Does the oil smell strong of gas? I have heard of some pump failures where gas was leaked internally into the crankcase.

drewfever1020 · 07-13-2008, 03:33 PM

i had the same problem to.
it was my fuel pump, it had got clogged.
check ur fuel pump, blow it out!

Troy Campbell · 07-13-2008, 03:46 PM

I will look at all of the things yall suggested, I think yall very much for helping me..... I just went out and ran it while it was cold, when I started it, I had 6 psi of fuel pressure, the hotter it got, the pressure started to drop. When I shut it off the pressure was at 3. The fuel line coming off the tank to the pump is pulsating and the needle on the pressure gauge reflects this. I will look at the sending unit sock in the tank to see what it looks like... I drove the truck yesterday, I put about 100 miles on it, that was the first time in about 6 years it has been driven that far.

07-13-2008, 02:00 PM	#1
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	A second opinion I was driving home from a car show yesterday, my 71 chevy p/u started loosing power. I have a 402 BB , with a Elderbrock 600 cfm. The fuel pressure regulator gauge said 2 psi, I have it set on 6 psi. I increased the rpm, the fuel pressure went to 1 and my glass fuel filter went empty. I believe my fuel pump is weak and going out. Does that sound like a fuel pump to yall?

07-13-2008, 02:14 PM	#2
Willys47 Registered User Join Date: Dec 2007 Location: Nanaimo B.C. Posts: 604	Re: A second opinion was the gas tank empty? maybe vapor locked line? __________________ I was hooked on these trucks since 1982 when I drove my budys fathers 1968 Custum GMC 396 automatic dana 60 rear with a power lock diff what a ride more fun then we will we can ever tell!!

07-13-2008, 02:22 PM	#3
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	Re: A second opinion The fuel tank was 1/2 full, I thought it was vapor locking at first, but when I finally got it home and let it cool down, it done the same thing again. When you acc, the fuel pressure gauge goes almost to 0 and the glass fuel filter goes almost empty. It has a mech fuel pump on it.

07-13-2008, 02:22 PM	#4
steelhorse Senior Member Join Date: Apr 2008 Location: Franklinton NC Posts: 1,309	Re: A second opinion Fuel pump/out of gas/is the cap vented possible causing a vacumn on the tank?

07-13-2008, 02:28 PM	#5
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	Re: A second opinion The truck had gas, the cap is the same one since 1971. I wonder should i start it with out the gas cap and check my fuel pressure?

07-13-2008, 02:47 PM	#6
fine69 Senior Member Join Date: Dec 1999 Location: Urbana,Ohio,USA Posts: 4,618	Re: A second opinion Take the fuel line off the pump. Blow back through it. See if its clogged up. __________________ 2008 Chevy HHR 1/2 panel. 1949 Chevy Panel truck(just sittin, waiting) Board member #6

07-13-2008, 03:06 PM	#7
dwcsr Hollister Road Co. Join Date: Apr 2005 Location: Houston Posts: 6,134	Re: A second opinion I had the same issue on a 77 with dual tanks. I never did find out what it was but I had replaced everything from the line on the frame forward and used an electric pump. I suspected it was a clogged pickup or a rotted rubber line out for the tank or possibly both. It would start out a 7 and go on a 2 mile run and be down to 2-3 or less.

07-13-2008, 03:17 PM	#8
Boog laying low Join Date: Mar 2001 Location: Searcy, Ark. USA Posts: 13,427	Re: A second opinion The strainer in the tank may be stopped up. Also do you have a filter between the tank and the pump? Pull the oil dip stick. Does the oil smell strong of gas? I have heard of some pump failures where gas was leaked internally into the crankcase. __________________ Boog 69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver primer is finer 91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said. I stand for the flag and kneel at the cross

07-13-2008, 03:33 PM	#9
drewfever1020 Registered User Join Date: May 2008 Location: san antonio, texas Posts: 412	Re: A second opinion i had the same problem to. it was my fuel pump, it had got clogged. check ur fuel pump, blow it out!

07-13-2008, 03:46 PM	#10
Troy Campbell Registered User Join Date: Jul 2008 Location: Sugar Land Texas Posts: 22	Re: A second opinion I will look at all of the things yall suggested, I think yall very much for helping me..... I just went out and ran it while it was cold, when I started it, I had 6 psi of fuel pressure, the hotter it got, the pressure started to drop. When I shut it off the pressure was at 3. The fuel line coming off the tank to the pump is pulsating and the needle on the pressure gauge reflects this. I will look at the sending unit sock in the tank to see what it looks like... I drove the truck yesterday, I put about 100 miles on it, that was the first time in about 6 years it has been driven that far.



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