All Small Six Fuel delivery issue in gear

[JStatic7]

Hey all,

After having 3 mech fuel pumps overpressurize my autolite 1100 and flood the fuel bowl, I’ve bought a fuel regulator. Interestingly, once I added the regulator, the car wouldn’t start. Today, I removed the regulator, running straight from pump to carb, and now I have some lean-sounding symptoms:

Car runs fine idling @1000-1100, stalls immediately once I put it in reverse. Enriched the idle mixture and raised idle rpms to 1200 which prevents dying immediately, but still sometimes stalls.

My biggest thing is that theres no more flooding, which makes me think this pump just dropped its pressure entirely, and now running lean.

Wanted to get some sound advice before making any decisions. You guys think the pump is bad? I have this electric fuel pump I can put on the car as well. It’s rated for 3-5 psi, so would running unregulated be fine?

 

[vssman]

There’s only one way to tell. You have to put a gauge on the pump and see what the pressure is. If it is low, I’d also check volume by pumping into a container.

For the electric, I’d do the same and put a gauge on it to verify. If it is 3-5psi, then you should be good to go without a regulator on your 1100.

 

[63 Sprint]

Today’s aftermarket mechanical fuel pumps are problematic. Members are having such a high failure rate that many decided to take sound advice given here to go electric.

I’ve given up on mechanical fuel pumps years ago. Today’s good electric fuel pumps are much more reliable and electric fuel pumps have some good advantages.

I do recommend a fuel pressure regulator with a pressure gauge and return line to the fuel tank.

Do a search and you will find threads about issues with mechanical pumps and advantages of electric pumps.

Below is a good thread to start with.
Click on the link below:

All Small Six Thread 'Fuel pump madness'

Oct 6, 2025

Long time no see

Back again as the marquis has once again decided to stop running.

Anyone seeing issues with new mechanical fuel pumps being dead straight out of the box?

My car died on the way home from buying groceries, did some quick troubleshooting to see no fuel getting to carb.

Ran to O'reillys and bought the pump they had in stock for $40.

Put it on the car, still nothing.

Got the car towed home. Poured gas in the carb. It runs.

Order a carter pump from rock auto for $20.

Same problem. No fuel getting to carb.

I tried blowing air through the fuel line and got gas to...

• marquis83
• Replies: 22
• Forum: 144-250 "Small Block" Six Performance

 

[DON]

With all the current issues, I think two guages, one before the regulator to monitor pump operation and one after the regulator to monitor regulator function. You can tell at a glance the status of the fuel supply system

 

[drag-200stang]

Remember that, if you think that it is air/fuel related it can be ignition related and if you think that it is ignition related it will be air/fuel.
I had an ignition switch that had me chasing my tail and the Mustang was only four years old.