Fuel Issues

[E5USMC]

My CSX car has both the dual electric fuel pumps and a Carter High Performance M6905 manual fuel pump on my 427 SO.I noticed today that while running on the interstate at around 75mph / 2800-3000 rpms on just my manual fuel pump it started to stumble and die....as soon as I hit my electric pumps it it cleared right up. When I got home I unhooked my fuel line for the carb and test the fuel flow with both the electric pump by turning it on and the manual by turning the car over. Both moved fuel with the electric having a much higher flow.

I assume my manual pump, while it look to be moving fuel pretty decent, seems to be falling short in some way. The pump has less than a thousand miles on it. It may be defective or I wonder if it might have gotten some trash or debris in it causing it to not move the fuel as well.

Thanks for any help or advice,
MM

[Gaz64]

If the electric pumps are series with the engine driven mechanical pump, then the electric pumps are a restriction when not in use.

They really should be plumbed in parallel.

My 2c.

Gary

[Ron61]

I agree with Gary. If your electric pump is in series with the manual pump then the manual pump has to pull the fuel through the electric pump and that is going to cause it to have to work harder to get fuel to the engine.

Ron

[E5USMC]

Good point..... I’ll take a look and see how the fuel system is plumbed.

MM

[Frank Messina]

Looks like somebody got carried away in the fuel supply department. There is no need for two electric pumps but since you do have them they need to be fed separately from the tank and the output combined via a -10 Y to the main supply line to the front. If they are in series you will have another supply problem if one quits. If you intend to keep both the mechanical and the electrics the electric pump(s) need to run all the time. The mechanical can't pull the fuel through the electric pumps at a sufficient rate to supply the engine's needs.
Frank