Random Poor Running/Stalling


Veteran Member
Oct 1, 2016
Waupaca WI
Well again what does your voltmeter show when in the low RPM's. Not sure how you wired in the electric fuel pump. two things come to mind either low voltage or the pump wiring is reversed. I did bring up crud in the fuel bowl but i am sure you have ruled that out.


Veteran Member
Nov 13, 2020
I know that pump is not the best and my mounting could be compounding the problem, butthe previous owner daily drove the car for 3 years this way. Unfortunately, I have a late model block without fuel pump provisions.
I’m assuming the pick up is 3/8”, but I suppose it could be smaller. It’s just a stock replacement from one of the parts houses.
Appreciate the offer. Pump is not PWM, it’s just a smart controller with built in relay that uses the tach signal to the keep the pump running. I installed it for safety in case of a crash. I have it wired directly to the battery and am using it’s internal relay to fire another relay, so it’s not even carrying pump current. I’m still suspicious of it randomly cutting out though.
I plan to monitor fuel pressure and voltage on the coil hot wire.
On vacation at the moment and probably won’t get to it until week after next.
Last edited:


Veteran Member
Sep 8, 2015
OK, from the sounds of it, it could be a combination of mounting location/pickup and/or electrical/relay issues.

I've been down this road so many times decades ago with electric pumps.....just went back to the "KISS" way of doing things.

A good investment is an AFR gauge, that may in fact point you in the right direction just as quick as the fuel pressure gauge.


Veteran Member
Aug 18, 2011
Upstate New York
I had this same issue many years ago. I'm not saying this is your issue, but you could try it and see what happens. I removed the fuel line connections at the fuel tank outlet and fuel pump inlet, then blew it out with compressed air into a paper towel. I had a large amount of rust and crud that came out. Problem went away.

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