New fuel pump= flooding and gas every whare.
 

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?

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

sub'd

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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?

:chevy::chevy::chevy:

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

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

Re: New fuel pump= flooding and gas every whare.
 

5 psi in mine

Re: New fuel pump= flooding and gas every whare.
 

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.

Re: New fuel pump= flooding and gas every whare.
 

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!

Re: New fuel pump= flooding and gas every whare.
 

I ordered a holly inline pressure regulator with a mr gasket gauge and some 3/8 fittings. That sould be every thing I need.

Re: New fuel pump= flooding and gas every whare.
 

If you go w/an Edelbrock you will have to get there fuel pump which puts out 6 lbs or regulate your current pump to put out 6 lbs. I have one and am very happy w/it. Check this forum for jet and needle suggestion as stock can be a little rich,easy to change out. The Q-Jet manifold won't work w/an Edelbrock and a new Manifold to fit isn't that much and I hear adapters aren't that good, so it's good to go w/ a new manifold.
What the heck it's just money.

Re: New fuel pump= flooding and gas every whare.
 

I used the same basic set up. It worked very well for me. Try to find a place to secure the regulator. Keep us updated.

Re: New fuel pump= flooding and gas every whare.
 

First a QJet on a 307 is overkill. Second they only need about 3/4 lbs. third why replace the carb if it was fine before ? Way to much pressure. I have a fuel regulator if you need one ..Jack

Re: New fuel pump= flooding and gas every whare.
 

I got a regulator orderd. Not going to change it if that's the problem. And there's no kill like overkill.

Re: New fuel pump= flooding and gas every whare.
 

I put a new fuel pump on a Chevy truck I had from NAPA and the carb started flooding.

I rebuilt the Qjet and it still flooded eventually I put a pressure gauge on it and it was putting out 12 lbs.

I got another pump and it was fine.

I believe the quality control is just not there anymore on parts.

That was my experience. Good luck

Re: New fuel pump= flooding and gas every whare.
 

BUDS56, Best answer I have read.

Re: New fuel pump= flooding and gas every whare.
 

I'm just curious about this. Why buy a mechanical fuel pump for an 80s chevy pickup if you're going to put it on a 71 pickup? When I needed a fuel pump for my 69 pickup, I just went up to the car parts store and got the pump for a 69 pickup. I took the old one with me to the parts store so I could be sure it matched exactly. That way I didn't need to change the fuel fittings or fuel lines.

Re: New fuel pump= flooding and gas every whare.
 

That's all they had. They did not have one for my pickup but they did for 80s chevy. I figured they would be the same besides the carb feed tube. Wich is not a big deal

Re: New fuel pump= flooding and gas every whare.
 

Quality control of our vintage parts has gotten to be a big problem lately.
I got a new fuel pump from O'Reilly's, when the old one on my '71 GMC Jimmy w/ 350 SBC blew out after several years. This Chinese pump lasted 100 miles until it started spewing raw gas. I got my money back after being towed home. Then I tried another fuel pump from Auto Zone. Delphi, "Made in Troy, Michigan," they said. It was made in Korea. It lasted a year, then stopped pumping.
I called my local NAPA, they had stopped selling mechanical fuel pumps for SBCs, and suggested I convert to electrical. No thanks.
Finally I got an AC Delco pump at Merle's, a local auto parts outfit, and it's OK for now.
When I saw a woman on Craigslist had a NIB Carter mech fuel pump for a 350 for $15, I jumped on it. They had kept it as a spare in their motor home.

I found similar problems with getting a P/S gearbox replaced under a lifetime warranty. O'Reilly's paid me $300 to 'buy out' my Checker Auto Lifetime Guarantee on P/S gearboxes, when they couldn't get that vintage part anymore. And Auto Zone stopped listing parts for trucks over 50 years old.
I came out ahead by buying a reman Cardone gearbox from Rock Auto, but it's no longer warrantied.
Auto parts stores don't respect our vintage rigs as dependable work trucks anymore. It's just a hobby toy to them, so any shiny-looking part wil do.

Re: New fuel pump= flooding and gas every whare.
 

Having an Edelbrock carb, I knew I had to limit the fuel pressure and that the mechanical fuel pump was likely putting out 9PSI or higher. I wasn't sure if the Mr Gasket 9710 1-6PSI regulator was doing the job or not, so I also installed this VDO fuel pressure gauge and was pleasantly surprised to see it was made in the USA. Summit P/N VDO-153002, $20.57.

Re: New fuel pump= flooding and gas every whare.
 

Problem with older NOS or NIB fuel pumps is if they were made pre ethonal they wont last very long. The rubber diafram will turn to mush . Had it happen on my Studebaker older AC Delco in the box never used lasted a few months .

Re: New fuel pump= flooding and gas every whare.
 

Dont run ethonal. Problem solved.

Re: New fuel pump= flooding and gas every whare.
 

Good point. The last 2 or 3 fuel pumps were Asian. I thought that was the reason. They should have adapted to the newer fuel formula by now, but only if they care.
I have a 1963 model year 292 L6 core. It has a rebuildable fuel pump. [If you can still get the kit.] The kit cost more than a complete later pump. I always figured to ''upgrade'' to a later style non-rebuildable fuel pump, when the time came to put it on the road, but now, if I can get an alcohol-compatible diaphragm for it, that will be better. [Big IF.]
Of course the L6 fuel pump is not the same part as an SBC. It works ''upside-down'' to the small block's orientation. But maybe 283s, 327s of the same vintage used a rebuildable style?

Re: New fuel pump= flooding and gas every whare.
 

Got the regulator installed today. I was getting 9 psi. Haven't adjusted it because when I installed the fittings I could not find any thread sealer. Being pipe thread I thought maby i could get buy with out it. Well i cant. It leaked really bad. So i have to take it back off and seal the fitting. Not a big deal.