I have an 86 3.4pr and have been blowing fuel pump fuses somethin fierce. I got a new pump, new strainer, new fuel filter and swapped everything out no problem. The system charges to 40 odd psi as it should. The interior of the tank was pristine - no rust or particles.
Thing is, since I swapped the pump, it's had what I think is an unacceptable whine to it...as if it's struggling to do its job (but the whine doesn't increase with load on the engine). Seems like the car has diminished oomph at high RPMs. After about a week of doing perhaps five trips, tonight the fuse blew again for the first time since changing everything as I was taking off in first gear.
Any ideas what the problem could be? I reused the old pulsator when changing - that shouldn't be a problem right? When I had everything out, I made sure to check all the wire insulation from the sending unit to the firewall for any potential shorts, but didn't see any evidence that was a problem.
You typically don't need the pulsator with most modern pumps. If you have a turbine-style pump, and you probably now do, it runs quieter than the older gerotor pumps, draws less current and doesn't produce the varying pulsations that required use of pulsators with the older, gerotor pumps.
Did the evap line test and it works properly (blew in lower hose - not able to push air, applied vacuum to upper hose and then was able to blow through lower hose). I also applied vacuum to steel fuel vent line, and then was able to release it by opening the gas cap, so there's no blockage.
Guess it's dropping the tank again for me...unless there are any other ideas out there.
I was thinking the solid ones could also get crushed?
Not if each one was located correctly in its "track".
In any case, the tank only goes up so far, and "over tightening" of the straps wouldn't move the tank up any higher.
Originally posted by tnkgnr:
Any ideas what the problem could be? I reused the old pulsator when changing - that shouldn't be a problem right?
Well, there's a good chance that this pulsator is 34 years old. Perhaps it doesn't seal as effectively as it used to, and the fuel pump is spinning like crazy (because of less load) due to fuel leaking past the pulsator/pipe connections. How quickly does the fuel pressure drop when the engine is turned off? I wager it drops very quickly.
[This message has been edited by Patrick (edited 11-09-2020).]
All right, new pump/strainer installed and running. Will start driving it tomorrow and we'll see if the fuses keep popping. I ordered up a Bosch one this time...was pretty nervous since the polarity appears reversed from the original.
Popped another fuse on the short test drive. Again while taking off in first gear. I disconnected the supply line at the fuel rail and primed the pump - when I did so, the pump was nearly silent...so I'm thinking maybe some sort of obstruction might be in there?
With the return line disconnected, the pump still makes the loud noise and the pressure spikes to near 80psi. The fuel does come out of the return line, but more of a very quick dribble vice the flow from the supply line.
I guess this test confirms that the issue is somewhere in the fuel rail (I suspect the pressure regulator, which should be here tomorrow).