Mechanics

FUEL PUMP RELATED PRLOBLEMS

1991 Honda Civic

Engine Mechanical problem
1991 Honda Civic 4 cyl Two Wheel Drive Manual 120000 miles

I have a1991Honda Civic hatchback. I have towed it home from work 3 times now and I am not taking it out on the highway until I get this matter resolved. If at all possible PLEASE HELP! Here is what I can tell you thus far. I am on my 5th fuel pump, the one that I have in there now is really abnormally loud, just like the previous ones that went bad. I think that I have found out why they went bad. So for you to help me this is what I do know. Whom ever had this car before me must have had problems with this thing and traded it off, now it is my problem. I traced the wires from the fuel pump and they go directly to the fuse box. The diagram that I have obtained shows that the wires should go from the fuse box, to the fuel pump relay, then to the fuel pump. They went directly from the fuel pump to the fuse box. Heres where I need the help! I need to know the correct way in which the wires should go from the fuse box, to the fuel pump relay and to the fuel pump, correctly. I have done some expeimenting with some short made up wires with aligator clips on both ends as to try and figure which way it needs to be wired up the correct way with a process of elimination. I think I'm on to something here but not 100% positive if I have it wired the right way or not. Right now I have it so that when I turn on the ignition the pump turns on and after pressuring up it shuts back off until I start the car and then after the motor starts the pump doesn't ever shut off until I turn off the key. Is this the way that it is suppose to work or should the fuel pump relay turn it off and on while running down the road. I know that this fuel pump is on its way out but I was hoping that I could get it fixed correctly before I replaced it again. It is still under warranty so not to worry there. I think that I am getting closer to fixing this problem but I just need a little expert advice to make sure that I am on the right track and get this fixed and reliable again. The way that it was explained to me is that when you turn your ignition key on, it should cause the fuel pump to pressure the system up and then after pressuring up it should shut off the fuel pump until the motor is running and then calls for more fuel to maintain a constant pressure. This is done by the fuel pump relay swicth which is located under the dash on this model and maintains the pressure. I have removed the fuel pressure relay switch and have tested it twice with the shop manual that I have for this car. It checked out OK both times. I have also replaced on the out side chance the fuel pressure regulator with one that I know works just fine. So where should I go from here? I have cut a hole in the car floor as to make it easier to acsess the fuel pump in the tank. I can now change one of these fuel pumps in about a half an hour, that includes removing and replacing the rear seat in the car. Start to finish, not a problem with the little " door" that I now have. I really want to get this car up and on the road again and dependable so that I don't have to tow it home 35 miles one way from work in the middle of the night. That really stinks!
Avatar
James Curley
September 21, 2009.




Hi James Curley,

Thank you for the donation.

The fuel pump should prime for 2 seconds until the Check engine lights goes off during initial ignition on condition and will continue to run when engine is running. When engine stops/stalls, the fuel pump should stop working.

For the year model, the PGM-FI maiin relay is known to fail intermittently causing the fuel pump to stop. Remove the relay and check the circuit board for cold solders. You can see cracks on the solders and resoldering would make the relay good if not better than new.

When this relay fails, it is intermittent so bench testing might not get the correct results. You are correct about the system working so I believe you have got the system and wiring correct.

With direct power from the ignition to the fuel pump and having to tow back indicates either the circuit has a fault or the fuel pump is bad and fails intermittently. Check the fuel pump grounding, it could be poor causing the fuel pump to fail intermittently.

KHLow2008
Sep 22, 2009.


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