Fuel Pump - No Power

[jmp]

I have a 1991 with a hi-boost CTSC, methanol inj and AEM, walbro 255 fuel pump and 550 injectors. I have put many thousands of miles on my car with this setup.

The other day went to start it and my fuel pressure gauge never "jumped" from 0 to around 40 psi as it normally does after about 1-2 seconds of holding the key at about 3/4 of a full turn. The car will not start. The car behaved completley normally prior to shutting it off the previous drive.

I was certain it was the main assembly relay, but replaced it today and still same thing. Fuses all appear intact.

I went to check my fuel pump resistor and noticed it is missing which I presume was/is part of the swap of the stock fuel pump for the Walbro???

Could be something with the AEM??? Any and all opinions/comments/suggestions will be appreciated.

 

[Daedalus]

Maybe the pump is out?

 

[GreyHoundSteve]

Im under the impression that the main relay goes to the fuel pump relay, if the main is good then i would check the fuel pump relay next and go on down the line from there.

 

[RON98]

you will be able to hear the warbro kick in. its a loud pump.

I would only pull the pump as last resort since pulling the tank is a pain in the butt.

im trying to remember how the wiring goes on the fuel pump but what you can do is put a 12 volt curret to the pump through the 12volt and ground wires.

if the pump turns on.. then its other problem such as your main relay... if its dead, then you have a pump problem.

easiest way to supply 12 volt is use 2 speaker wires and have a alegator clip on each end. you can use the battery or you can use the fuse box in the engine compartment as a source of 12 volt to test the pump.

also there will be a fuel pump relay. i would check that also. easy to do, just shake it. if it makes a rataling noise, its bad.

i dont remember where the fuel pump wires are again,my mind is blank, i think its on the passenger side of the engine bay by the fuel filter, but i would test the pump first before running out to change the main relay and all the other stuff .


have a good weekend!

 

[jmp]

Thanks for all the comments.

The fuel pump has about 5k miles so hopefully it is still good.

I replaced the main relay assembly so it is not that.

The fuel pump resistor (ie a black box with fins located near the fuel pump is gone - when the Walbro went in this went out. For this reason, i am not sure where to look for the fuel pump relay as I had thought it was near or at the resistor???

 

[Briank]

The fuel pump high relay only comes on over 4000 rpm to short out the fuel pump resistor. Since you don't have a fuel pump resistor then it's out of the circuit and has no effect. If your Main relay is good then I would say the pump is suspect, powering up the pump as suggested above will confirm or eliminate it very quickly. If you can locate the connector for the fuel pump resistor that would be an easy place to test power the pump.

 

[jmp]

Thanks BrianK.