Tossing fuel pumps like crazy

[68Promod]

I have a 1990 with a 5.7, the truck will bog and stumble at anything over about 10% throttle, so much so that I cannot get it to over 25 without it falling on its face and trying to die, it has not seen 30mph in 3 months now. Prior to this I went through 4 fuel pumps in 3 months about 2 miles of on road use combined. I have changed just about every sensor and relay that you can. Now for what I do know. With it in this current bogging state I have only 7 psi of fuel pressure at idle, it will jump to 12 psi very quickly right after it is started but once any gas is applied it drops to 0 and then returns to 7 when I let off but it will maintain the 7 psi for a while once it has been shut off. Yes the fuel tank is corroded I have a new tank on the way. I also know that the fuel pump only gets 8.4 volts with the truck off. Is the tank and the low voltage the reason for this issue and the burning of fuel pump or is there something I’m missing. If the low voltage is a cause, how do I fix it? Thanks in advance.

 

[Carlaisle]

The voltage is definitely a problem, although it may not be the only one. Does the pump have a good, clean ground? A poor ground is a common cause of the low voltage/high amperage condition that tends to fry fuel pumps.

 

[68Promod]

The voltage is definitely a problem, although it may not be the only one. Does the pump have a good, clean ground? A poor ground is a common cause of the low voltage/high amperage condition that tends to fry fuel pumps.

Yes it is clean, though when I go to change the fuel tank I will wire wheel the ground again to be sure

 

[Caman96]

What brand fuel pumps are you using?

 

[68Promod]

What brand fuel pumps are you using?

I had been using acdelco, but the orileys brand has been the most recent one that lasted the longest and is still in the truck at it’s current state.

 

[evilunclegrimace]

Where are you checking fuel pressure, before or after the filter? When you replaced previous pumps was the sock plugged? Have you checked the wiring from the pump connection back to the relay for excess resistance?

 

[fancyTBI]

Doesn’t low voltage kill fuel pumps?

 

[Sean Buick 76]

Have you considered the possibility of the tank being rusty on the inside? That will also kill pumps. What’s your voltage at the pump? Voltage under load? I would consider running a jumper wire with an in line fuse and a toggle switch if you actually have voltage issues.

 

[68Promod]

Where are you checking fuel pressure, before or after the filter? When you replaced previous pumps was the sock plugged? Have you checked the wiring from the pump connection back to the relay for excess resistance?

i am checkking pressure where the fuel filter, i remove the filter and put the gage there, cheching for restistance will be my next step when i drop the tank tonight.

 

[68Promod]

Have you considered the possibility of the tank being rusty on the inside? That will also kill pumps. What’s your voltage at the pump? Voltage under load? I would consider running a jumper wire with an in line fuse and a toggle switch if you actually have voltage issues.

the tank is rusty on the inside, i know that was a huge part of fouling fuel pumps, i ordered a new fuel tank, but the low voltage also concerns me and i feel contributes to it, im just trying to find a way to fix the low voltage.