Hello,

I have a 1986 C20 3/4 8cyl 7.4L suburban. When I bought it there was a Holley Blue Electric external fuel pump (push pump) mounted on the right side, behind the rear passenger door, on the chassis frame. Turn the key, but not start the engine, and it is historically and noisy humming pump (an important detail).

I drive fast and sometime press the uphills with this rocketship. Having slight fuel low problems going uphill, I decided to buy a new Holley Blue Electric fuel pump. I have a regulator with 5.5 settings each 0.5 progressions. I run the 1986 currently at 5.0 (high side).

The pump has started to quit (meaning no noisy hum) and it happens randomly (the profession of ignorance). I turn the key, and there is no hum. Pump the gas pedel and try to start it. No ignite. Pause every 30 seconds for 5 minutes an eventually I get the pump to start humming again (unexepectedly) and when I try to start the engine, we ignite and off goes the rocketship again, 85mph, 90mph, 95mph, ... (you get the picture here).

OK.

1) This random pump pump stopping happens going slow or going fast and never in any expected turning position, nor at any specific road pitch, nor cold nor hot weather. It just happens unexpectedly.

2) I drive about 20 miles per trip. Sometimes 30 miles per trip.

3) Sometime when the pump dies and speed starts to drop rapidly, after about 20 seconds the pump suddenly hums again, and off the rockship goes again as if nothing ever happened (pick your speed, slow, steady, and even pedal to the floor). Nothing seems to phase the pump after it "recovers".

Thoughts:

Remember this is a new Holley Blue Electric fuel pump with 14psi and 110gph at 3/8

A) Electrical discharge Theory: Ground for the pump is not the ground I think it is. Instead, like a capacitor the vehicle is building up charge. When charge reaches a defined level, varying locations while driving. The "capacitor" vehicle discharges and knocks the pump out. The theory is that the pump restarts later because we have retuned to "ground". One day I had the truck idling and I was under the truck when I thought I heard a load zap-snap sound (a softer sound than you hear when a welding rod first touches metal when welding). It only happened once but at least you know now why I have an electrical discharge theory. Yes, my ground wire goes to the chassis.

B) The Overtax Theory: The pump is working hard pushing 100gph to my 454 7.4L that gets 10 to 11 mpg. I live in Colorado. Home is at 6500 feet. Work is at 5280 feet. Drive "downhill" to work from home, the pump never seems to die. Driving "uphill" to home from work and it might die 0, 1, 2, 3, or 4 time over 20 miles. Drive in the cool morning, the pump never seems to die. Drive in the warmer afternoon and the pump is likely to die.
i.e. Does a Holley Blue Electric have a shutoff of some sort and for what criteria??

Idea #1 : Maybe I need a pump doing more than 110gph

Idea #2 : Maybe I should put two pumps on and turn down the regulator for each OR have a cabin switch ready to engage the second pump.

The problem is getting progressively worse meaning the pump failure occurs more often. Hey, wait five minutes, keep trying to restart and eventually the rockship ignites and off I go slow, fast, or pedal to the floor.

-- Crazy Canadian

 

one thing i can see is that you are running way to much fuel pump ! the blue one is a racing pump .should be running at most the red one and that can be to much .my old mad put a red one on his 79 suburban with a 454 and it was to much fuel ! he finally went to a walbro pump on demand unit to assist the factory mechanical pump ,and every thing was fine about 5 psi .

 

Note: Thanks "old dog" for the Red Electric detail (am reviewing the Red while troubleshooting). Now you know why I call this 86 my rocketship (this suburban screams when I put the hammer down).

Troubleshooting:

A) New pump shows 12v even when it stops

B) Put old pump back on and pump continued but 20 minutes into the ride fuel delivery stopped (pump kept humming).

C) Have an in-line Spectre Performance Regulator (two feet before entering carb) plus a PSI pressure gauge 1 foot before carb. Running old pump (while humming) I noticed the Sprectre Performance Regulator was showing no PSI at the guage. Took packing tape and taped down the regulator dial switch (opening the reg) and drove for 40 minutes without issues. So, this means fuel flow was stopping at SP regulator, causing pump to pump until it shutoff (tried to pump to nowhereland).

D) Put on a new Spectre Performance Regulator and am now driving the 86 for a few days to see if I got the problem. I set in-line SP regulator to 4.0 of 5.5 (instructions say 3.0 to 5.0 for 454). I need to drive the rocketship for a few days and check performance between 3.0 to 5.0

E) Next steps? Check regulator at carb + review "old dog" Red Holley advisement

 

yea the blue just to easily overrides needle and seat's and lower quality regulator's especially with the alcohol in gas now ,they are for racing and intermittent use .i got one i haven't used for about 10 years when i retired my small block Vega . i used to run straight methanol and it gave you a lot of corrosion problems in the fuel system .