Weird Stuff...Fuel Pump Making Noises While Losing Throttle Control

[chryguy]

Had a drive-ability issue on my Van a few months ago, where it would stop responding to the throttle input, start missing, and die.

It would restart when I cycled the pump, then run for 30secs to minute, start missing and die again.

Since I was close to home (20 min away) I continued driving and found I could keep it from dying if I violently feathered the throttle, pumping the gas pedal like mad...then it would catch and run until I let off the gas. Letting off the throttle would cause it to sputter and die.

When I got home I played with it a little and it would restart (after dying) without cycling the pump, but would start to miss and die in 10-30 secs.
I noted that when it would start to run badly, the fuel pump started to make some...ahem..."interesting" sounds.

It would get high-pitched and the noise would begin to fluctuate...sometimes dropping to a low growl before getting high pitched again. This would happen in the ten seconds or so while it ran badly before dying.

Sooooo,

I put in a new Airtex pump assy from RA, into a nearly new, spotlessly clean fuel tank, with a new piece of return hose (in the tank). I used new fuel injection hose in the back, on both sides.

After restarting it, I drove it around for a good portion of the day,and other than the idle being lower than before(?), it seemed to run well.
Tonight when I got home I decided to let it idle while I moved another vehicle...and when I got back in I noticed the pump was singing again, and when I stepped on the throttle it didn't respond.
It didn't die this time, but I had the throttle halfway to the floor and it didn't move. When I stepped into it a little more, sputtered a little, then after a couple seconds it finally started responding.
When it responded to throttle input, the pump stopped singing.

When the pump isn't singing it drives fine, and does so for extended periods of time. Makes me think it's not the pump, since it doing it with the new pump.

Anybody ever encounter these symptoms?

Anybody have any ideas?

Thanks in advance...
CG

[RoadWarrior222]

No mention of filter change, and did you check all the lines for being crushed?

[shackwrrr]

High resistance in the asd relay. Measure voltage when it starts doing it.

[BadAssPerformance]

Check voltage at the pump while it sings and not, could be wiring. Also check fuel pressure, could be some sort of blockage somewhere?

[RoadWarrior222]

Yeah wiring too, could be a bad ground. Or a piece of scale or crap swirling round in the regulator or something.

[chryguy]

Thanks for the ideas...

Part of the weirdness is, it runs fine for long periods, then starts running bad.

I was thinking wiring or ASD...I think I'll swap out the ASD for a known good one.

I'll visually check the lines and wires for crushing and such.
After swapping pump/tank, the fuel gauge isn't working, so I'll be dropping the tank and checking the wires/sending unit...

I have not checked pressure when it's doing this...that will be something I do right away. I'll have to go buy a high pressure fuel gauge...I made the mistake of letting someone borrow (steal) it.

She's rather rusty underneath...where does the fuel pump harness get ground?

Thanks again, I'll check this stuff and let you know what I find...

CG

[RoadWarrior222]

Well, I just flicked through my '86 van factory manual, but they were all using mechanical pumps still that year... best guess is that it's somewhere in the tailgate area, inside, maybe shared with the light grounds.