injector fuse keeps blowing - HELP!

[poolemit]

Hi there! I'm having a bit of a problem with my '89 Accord LX-i. For some reason, the injector fuse (in the fuse/relay box under the hood) keeps blowing. I disconnected the injectors/resistor connectors but that didn't help so I was unable to pinpoint the short (I assume it's a short -- right?). I also ruled out the ignition switch by replacing it with an old one I had laying around -- same problem. I'm not too good with wiring/electrical problems but a friend of mine is gonna come and help me with it tomorrow so I'm seeing if anyone has tips or clues as to what/where the short is or how we could locate it. Or is there any way it may not be a short but something entirely different?

thanks a lot for any and all info!

[mpumas]

I gather that you are referring to fuse #1 (10A) which provides power to the injector resistors and the injectors. (The ECU provides a ground signal to activate the injectors.) That fuse also provides power to the ECU. What is between the fuse and the injectors/ECU is the main relay. Therein lies a couple of resistors, relays and diodes. You might disconnect the main relay and see if the short goes away. If it is not in the main relay, the next place to look is the ECU. Keep us advised on what you find.

[poolemit]

Originally Posted by mpumas

I gather that you are referring to fuse #1 (10A) which provides power to the injector resistors and the injectors. (The ECU provides a ground signal to activate the injectors.) That fuse also provides power to the ECU. What is between the fuse and the injectors/ECU is the main relay. Therein lies a couple of resistors, relays and diodes. You might disconnect the main relay and see if the short goes away. If it is not in the main relay, the next place to look is the ECU. Keep us advised on what you find.

Yes, it's the #1 fuse. We disconnected the main relay and the short goes away, so we tested the relay itself according to the honda manuals and it tested good.. we then tested the main relay harness and something interesting happened. According to the instructions, a jumper wire in the harness between the ylw/blk and blk cable WITH the ignition switch turned to 'ON' should make the fuel pump work, and it does. problem is, it also works if the ignition switch is OFF. so I guess we're onto something but I'm having trouble understanding what this means. any more ideas? i'm planning on replacing the fuel pump and main relay tomorrow just in case.

thanks a lot!

[mpumas]

Wires with power into the main relay is as follows:
yel/blue-from fuse 1 is always hot
blk/yel - is hot only when the ignition switch is on.
The yellow wire at the main relay goes to the fuel pump according to my book. So if you got the wrong power wire, the pump will run regardless of switch position. I guess the next thing to check is anything that connects to the ECU or the ECU itself. Troubleshooting the ECU is usually done by swapping out the unit and see if it fixes the problem. As for items connected to the ECU, you can disconnect the O2 sensors, anything that connects to any sensor in the engine compartment ie.distributor, injectors,throttle angle sensor, MAP. to name a few. Keep us informed.

[poolemit]

well long story short me and my friend could not find the short so we brought it in to a local shop. they say the problem is a faulty ECU so I found one but it's from a manual lxi while mine is auto. any idea whether they're interchangable?

thanks!

[poolemit]

FYI, it turned out to be a faulty ECU. problem solved.. thanks for the help.