Fuel delivery issue

Skytrooper · May 22, 2021

The Basics: 440HP, auto xmsn, Carter carb, electric fuel pump 115gph, 14psi (no mechanical pump), Mr. Gasket fuel pressure regulator.

The problem: Starts and runs at idle just fine for however long you let it run. Driving on the other hand has issues. First, when accelerating it stumbles unless you accelerate very slowly. Second, it will empty the carb of fuel and quit if trying to drive it anywhere near normally.

Without a mechanical pump when it quits from starvation, it requires priming the electric pump, line, and filling the float bowls before it will fire again.

Pump is low in engine bay. It should have enough flow to not be an issue and the regulator is to keep it from sending too much fuel to carb.

Any and all input is appreciated.

65wgn440 · May 22, 2021

Is this a new issue ? Most electric fuel pumps are pushers, not pullers, and need to be mounted close to fuel supply to operate properly.

pnora · May 22, 2021

How clean is the tank? Have you replaced the suction sock on the sender. If the accelerator pump works and the float level and drop is correct it seems to me that it can not pull the fuel. If the longer you run it the worse it gets pretty much confirms the suction sock is drawing debris from the tank and causing a restriction.

747mopar · May 22, 2021

I agree with 65wgm440, pumps are primarily pushers. Whether or not this is THE problem it's far from optimal. Regardless I would start with addressing it, mount it as low and close to the tank as possible. It could be several things though, regulator, plugged up fuel filter or sock, kinked fuel hose, bad pump, etc.

How many psi does the pump produce, is it low enough that you can run it without the regulator for a test? Is there an inline filter? Is the tank new/clean?

Skytrooper · May 22, 2021

Tank is very clean. I had it out last year and redid all fuel and vapor lines. It also got all new sending unit assembly. Tank is full with 90 octane non ethanol. There is a new fuel filter (in-line) between regulator and carb.

pnora · May 22, 2021

Is there a filter in the tank? If so then bypass the electric pump and run on the mechanical and see what it does. Only reason I question the filter in the tank is you think your tank is clean and it might be but there also could be some odd crap getting pulled to the tube restricting the fuel. Once it sits it drops away. Re reading your first post with you have to feather it makes me think there is a carb issue. Pull the line off the carb. Get a gallon jog and mark it at 1/4. Stick the line in the jug and start the car. Time how long it takes to pump 1 quart. That should tell you something right away.

Skytrooper · May 22, 2021

I cannot run the mechanical pump, it needs a push rod and I have not been able to remove the pipe plug. The electric pump is the only pump I have available at this time. Tank was completely flushed last year when I had it out. It has new sending unit assembly. I only have 5 inches of rubber fuel hose between sending unit outlet and hard line on the chassis. That doesn't leave me any place to locate the electric pump closer to the tank. The hardline runs to the engine compartment. I could lower the electric pump in the engine compartment so it doesn't have to work as hard.

pnora · May 22, 2021

Does it have a sock in the tank?

Skytrooper · May 22, 2021

Yes, it does have a sock in the tank

66Satellite47 · May 22, 2021

The electric pump should be mounted near the tank. They like low suction losses. Locate the pump below the tank.

pnora · May 22, 2021

Skytrooper said:
Yes, it does have a sock in the tank

Good you need to protect the pump. Now run a volume test before the regulator and then do it after the regulator.

Skytrooper · May 22, 2021

Pump is too large to mount at the tank

pnora · May 22, 2021

I was able to mount a Carter electric back by the tank. As I remember it was by the upper shock mount.

Skytrooper · May 22, 2021

Yeah, the carter is about half the size of my pump. I will check for room

pnora · May 22, 2021

So do a timed volume test before and after the regulator. That is going to tell you a whole bunch of useful information. Being you are electric only see how long it take to pump 1 quart.

pnora · May 22, 2021

Skytrooper said:
Yeah, the carter is about half the size of my pump. I will check for room

A carter 4601 is pretty close to the same size. Plus it is quiet.

diesel_lv · May 22, 2021

I have run 2 different inline electric fuel pumps on my '67 Coronet for fuel injection. I used factory steel line while doing so. Get 10 feet of 5/16" or 3/8", whichever you are using, mount pump low on frame rail near tank. Run fuel hose from sending unit to pump. Then from pump back to steel fuel line. You want the pump w/in 3 feet, but I've gone 5 feet reliably, and at or below lowest level of tank. I will Only use Walbro inline. Super quiet and last forever.

BSB67 · May 22, 2021

Is the fuel tank/cap venting as it should?

Skytrooper · May 22, 2021

Flow test results:
With regulator, 36 seconds per quart
Without regulator 30 seconds per quart

Skytrooper · May 22, 2021

it is a 71 charger

Fuel delivery issue

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