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Sputtering after fuel cell installed

M1A1TankerTom

NAXJA Forum User
Location
California
89 comanche, 4.0 renix, auto tranny.

I dropped the stock fuel tank and installed a summit fuel cell and an walbro external fuel pump.

90% of the time the truck runs fine, but on several occasions the engine will suddenly begin to sputter and lose power. When the sputtering begins the more I press on the gas petal the more the rig sputters. Once the sputtering starts it will not stop till I turn the truck off and restart it, then it will run fine again.

The renix has a fuel pressure regulator on the fuel rail so I don't believe it's getting too much fuel. Any ideas?
 
I've had possible fuel delivery problems before, I hooked up a fuel pressure gauge and taped it to my windshield wiper. It often turned out to be something else, but at least I eliminated fuel as a cause.

You did jump or bypass the ballast resistor, I hope.

It may be totally unrelated to your fuel cell or the plumbing. Maybe do a quick volt check on your CPS.

Did you hook the fuel return back up? The stock fuel regulator is actually on the return side. Is the pump you installed unregulated? Many pumps are pressure matched to the application and don't require a fuel return.

Most every manufacturer recommends putting the pump in below the tank, which is hardly possible in many instances.

The pick up in your fuel cell? Does it happen with a full tank? On a steep incline, accelerating or braking?

Some of those external pumps have a fuel pressure regulator built in and it is often adjustable within a certain range. I'd read the destructions :) carefully.

Just some ideas and a few wild guesses.
 
Last edited:
Ballast resistor is bypassed.

I have not checked CPS, but truck never did this till fuel cell installed. Will check though.

Return line is hooked up. The walbro pump I installed is unregulated.

The fuel pump was installed below the fuel cell.

It has happened once with a low tank on level ground and once with a full tank on a incline.

Pump does not have a regulator built in.
 
Id think putting in a regulator would just help eliminate an issue with pressure surging or pump cavitation just incase even though it may not be the problem... My train of thought here could be wrong but if it was full and on an incline, the fuel going through the return line could be having too much resistance from the high capacity in the cell...
 
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