I was driving my car one day and it turned off on me all of a sudden. Pulled it over popped the hood and it turns out turns out a fuse blew and that fuse protects the PGM FI main relay (Pictures Posted). I got it too run for a bit but the fuse blew again. The car has been sitting for a couple of days, I asked around for some help and I was told it could be the main relay so I bought a new one, fuse still blew. I had a fuel pump kill switch and they said that could be making it blow, so I took of the kill switch and what do you know? it still blew. Has anybody had a similar problem? I am about ready to take it to a shop but before I do that I want to know if it something simple so I wont waste money too get it fixed when i could have done it myself.

 

You can start disconnecting things and then turn the ignition on and see if the fuse still blows. Start with the main relay. Then the ecu. There could be a wire loose and touching ground somewhere.

You basically need a diagram and then look at all the things that touch that fuse and test em.

 

Which PGM-FI Main Relay fuse blows, there are 3 of them?

Does it blow when you turn on the ign. or when cranking to start?

Is it a constant power fuse?

MM&Y of car would help.

It should be an easy diagnoses, the fix itself may be a little harder, depending on what is wrong, but nothing "backbreaking".

Your showing the engine bay fuse box, so I will assume it is the constant power fuse, it protects the wiring for fuel injectors, IGP1 and 2 of the ECM, some engine valve/solenoids heated 02 sensors, depending on MM&Y of car. 94

 

95 Honda civic. 31 one is what the fuse is labeled in the picture. it blows when i turn the ignition.

 

When i disconnect the main relay it does not blow.

 

What's the Ohm reading to body-ground at the power wire in the fuel pump connector?

 

That is a hot at all times fuse, the loads on that fuse are IGP 1 and IGP 2 to the ECU, it also powers the fuel injectors, heated 02 sensor(s) and some engine valve/solenoids, it is also the trigger, [internal] for the fuel pump relay, [very low current so unlikely it as the problem

Start by unplugging the injectors and the ECU and the heated 02 sensor(s) see what happens, if fuse does not blow, start plugging things in until it blows.

If it still blows you will need to find out what valves/sensors in your car are also powered by that fuse and unplug them. 94

 

actually thats wrong^
fuse 31 is not a hot at all times fuse, it is only hot when ignition is in run/crank.
and unplugging things will not diagnose a shorted wire, it will only diagnose a faulty component.

as originally stated, you will need to get a wiring diagram and start chasing wires testing for shorts to ground, and repair the short. I hightly doubt a component is causing the failure.

also, there's no point in testing the fuel pump power wire, it is NOT on this fuse. it has its own seperate fuse. this fuse is only for the relay, not the pump itsself.

 

unplug ecu. replace fuse. try again.

 

According to my diagrams fuses in the engine bay fuse box, [that relate to the PGM-FI Main Relay] are hot at all times, the two switched fuses are in the under dash fuse box.

I also never said the fuse was for the fuel pump, I said, "it is also the trigger, [internal] for the fuel pump relay".

Unplugging components will eliminate them as the problem. 94