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Fuel starvation

1K views 10 replies 5 participants last post by  spiderserie4 
#1 ·
Ok Team, here is my next challenge. I got the car up on blocks and removed the drive shaft and sent it down to the shop to have new u joints and carrier bearing installed. While I have everything out, I look and see the old gas lines, so I think, safety and decide to change them all to the fuel pump, and of course, both fuel filters. Done, alright, Now it won't start, So I go back under and note no fuel pumping out of the pump. Help please.
 
#3 ·
Its an 88 graduate. I have not checked any of this yet. AS all I did was change out all the hoses, I did not think it could be an electrical problem. I have a check light and an volt/ohm meter. Would I assume that if is simply used a set of jumpers off the battery, I should be able to make them work? I read I have two fuel pumps?
 
#4 ·
If the in-tank pump isn't working you may not get fuel to the main pump if the lines are dry as it won't be able to prime.

Do not run the main pump dry for any amount of time or you'll be buying a new main pump.
 
#6 · (Edited)
You don't need to prime the system. The in-tank pump is supposed to do that.

As you know, your car has two fuel pumps. What Gubi is suggesting in post #4 is that your in-tank pump may not be working, so fuel is never reaching your primary pump (the one you re-plumbed). I suppose the easiest way to diagnose that would be to disconnect the wire from the under-car pump, turn on the key, and listen for the sound of the in-tank pump. If you get silence, it's probably dead.

I must admit to having zero experience with these two fuel pump systems. Gubi: Would Doug's car have been running OK with the in-tank pump not working?
 
#8 · (Edited)
Yes, sending 12 V directly to the in-tank pump should tell you something. But as I said, I'm not familiar with those systems, so can't tell you which wire to connect. Two of those wires would be for the fuel gauge and "fuel low" light. Don't know what the fourth one is for - ground perhaps?

My suggestion of disconnecting power to the primary pump eliminates the need to determine which of those 4 wires to activate. Testing it that way would also detect the condition where the in-tank pump itself is working, but the circuit that powers it is dead.
 
#10 ·
Yeah, they can run with the in-tank pump not working. I knew when my in-tank pump failed because the main pump started making a noise from straining, but the car still ran.

Pink-white should be +12 for the pump, black is ground. You should just be able to send +12 to the pink-white and see if the pump works. There's also a short stepped rubber hose in the tank assembly from the in-tank pump to the metal fuel line: if that's busted the pump may be running but won't be able to get fuel to the main pump.
 
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