New fuel pump= flooding and gas every whare.

[71gmcC15]

So I installed a new fuel pump on my 71 gmc. And my quadrajet most not like it. It floods out and there's gas on the intake. And it won't start very well. If at all. Could it be to much pressure? It's still a mechanical fuel pump. For an 80s chevy pickup. Had to make the feed to the carb bigger. Could that be it?

[KQQL IT]

I had to put a regulator on my last new fuel pump.
Was doing 9 psi bought a rebuilt carburetor thinking it was the problem.

[Steeveedee]

You may have disturbed some crud and now it's possibly lodged in the needle and seat.

[geezer#99]

Could just be a stuck needle/seat.
What does ‘had to make the feed bigger’ mean?

[El Dorado Jim]

sub'd

[71gmcC15]

Well after some investigation it's getting way to much fuel. When running if I pinch the line almost shut it runs great again. And after I shut it off gas starts to run out the base of the carb pooling on the intake.

[71gmcC15]

Originally Posted by Steeveedee

You may have disturbed some crud and now it's possibly lodged in the needle and seat.

Possibly but not likely. Unless it made it past my filter my gas is nice and clean. The tank has zero rust or dirt in it.

[71gmcC15]

Originally Posted by geezer#99

Could just be a stuck needle/seat.
What does ‘had to make the feed bigger’ mean?

The feed line going to the carb was much smaller on the original pump. The new one was 3/8 inch. So I had to convert it over to 3/8.

[Daron65]

I had basically the same problem when I swapped in a new mechanical pump. I installed a Holley fuel pressure regulator from Amazon, added a dial guage. It was pumping almost 10 psi without regulator. I dialed it down and played with different pressure. My Holley Street warrior runs best at 6 psi. Total cost around $50

[71gmcC15]

Originally Posted by Daron65

I had basically the same problem when I swapped in a new mechanical pump. I installed a Holley fuel pressure regulator from Amazon, added a dial guage. It was pumping almost 10 psi without regulator. I dialed it down and played with different pressure. My Holley Street warrior runs best at 6 psi. Total cost around $50

I'm glad I'm not the only one that has experienced this. I've done some pricing any every thing I need is about $60.

[geezer#99]

Originally Posted by 71gmcC15

Well after some investigation it's getting way to much fuel. When running if I pinch the line almost shut it runs great again. And after I shut it off gas starts to run out the base of the carb pooling on the intake.

That action says the needle isn’t seating like it should.

[71gmcC15]

Originally Posted by geezer#99

That action says the needle isn’t seating like it should.

Yep. The pressure is over powering the needle and seat. So it just gives it more fuel until it floods and then continues to give it more. That's what I think is happening.

[geezer#99]

No.
You’re controlling the flow thru a needle/seat that’s dislodged by trash or the needle clip is installed wrong.

[garyd1961]

Try gently tapping on the carb where the line connects with the plastic handle of a screwdriver.(while it's running)

[AussieinNC]

Quadrajets should have an inlet fitting filter...it is most likely missing....if its missing, make sure you replace it...they are available from most auto parts stores...NOTE !!! There are two different length filters, one inch and two inch, make sure you get the correct one.

The issue you described is an obstructed needle and seat, most likely with junk from the lines or old pump....

You did not say why you changed pumps?

Is there an inline filter in the fuel system?

[toolboxchev]

Yea, I would try what Geezer and Aussien said first.

[71gmcC15]

I have ran this q jet for 2 years never messed with any thing. So the chases of the needle clip being installed wrong is out the window. I replaced the old pump with a new one because it was leaking realy bad. There is a inline fule filter. I dont have any of the original hard line left. As for the incarb filter being missing. Have know idea if its there or not never touched it. It was just fine till I put a new pump on. Pressure from the pump can blow passed the needle and seat if it's to much. I ordered a regulator. If that doesn't fix it then I gess I'm going to eldbrock

[KQQL IT]

I used a mr gasket dial regulator. With my gauge it about was about 1/2lb high. Set it at 4.5 psi on the regulator which was 5 at the gauge. Zero problems since.

[CCCC]

I try to buy replacement pumps that run 3 to 5 PSI (if i can find such) and have installed both Mr. Gasket and some other more expensive regulator as well - because the fuel pressure simply was overpowering the needle valve in a Quadrajet and in a Carter AFB. A carb that worked fine before the replacement pump acted just as yours - so the fix was needed.

Seems difficult to find a lower pressure pump for these applications. Recently went to an electric pump rated at 3 PSI and it has worked fine.

[Steeveedee]

I'd suggest taking it to a competent local mechanic.

[71gmcC15]

Originally Posted by Steeveedee

I'd suggest taking it to a competent local mechanic.

Key word there competent. I dont know of any . if it doesn't have a obd2 port they cant work on it

[71gmcC15]

What psi does a q jet like to see. I'm guessing around 4 to 6 max.

[KQQL IT]

5 psi in mine

[68is4me]

Quads don't like higher pressure fuel pumps. What brand of fuel pump did you get? The best I have found for stock pressures are ACdelco and carter pumps.

Put a pressure gauge on it to find out what pressure that you have. Like others have said you can always add a regulator.

[Killer Bee]

Originally Posted by 71gmcC15

Well after some investigation it's getting way to much fuel. When running if I pinch the line almost shut it runs great again. And after I shut it off gas starts to run out the base of the carb pooling on the intake.

this sounds very much like the new pump is overflowing the float's ability to shut the needle valve..

the needle and seat is a volume control opened and closed by the float to establish a working level the carburetor can draft fuel from..

if the inlet pressure is too great, the buoyancy of the float is not enough to shut the valve and creates a fuel flood through the vents..

do yourself a favor, install at least a gauge or regulator with a gauge.. it will eliminate guessing regardless of what type of carburetor you choose..

with the unknown quality standards of foreign made parts, you can't assume it's good until proven..

starting with known values and working your way through a sensible diag strategy will get you to the finish line..

that's what a competent mechanic does

good luck!