Like the title states, my fuel pump is stuck on when I turn the key. Walton 255, was stuck on with a full blown 340 as well.

I tried replacing the main relay, and it's still stuck on.

What could cause this? I'm guessing a bad ground but am hoping for more information than that.

I have constant power on a15 and the yellow/green wire at the pump has voltage.
I'm wondering what post number on the main relay could have a short which is causing the pump to not shut off.

 

Sounds like the switched energizing circuit (that activates the relay) is hot all the time. Check to see if you are getting 12VDC on this line, with engine off. Could be a miss-wiring.

 

Has any kind of rewiring been done or any damage to the main relay connectors?
ECU connector A15 grounds the fuel pump/main relay and you should have 0V when pump is active.

 

Yeah, there was an aftermarket alarm system that was taken out of the car at one point along with some other issues.

Its odd that this would occur out of no where, but it is what it is.

So your saying that pin A15(on ECU), which is Pin 1 on the main relay is a ground and should never see 12V? I thought Pin 1 and 6 from the main relay show a constant 12V??

Pin 1 and 6 on the main relay comes from the ECU.

 

windhund, do you know which pin on the main relay would be the switch?

 

What year model you have? I can check my Honda Service reference books.

 

When you turn the key to on position you should have battery voltage at 6 on main relay and ground on 1.
After 2s you still should have battery voltage at 6 but the ground connection at 1 should drop.

Here's the diagram, I'm hoping it's the same for all model years.

 

I have a 2003 AP1

The other day when I used a test light on pin 6, I had 12v there briefly (.5 second then it dropped) when I first turned the key.

Your saying I should have a constant 12v at all times on pin 6 when the key is turned ?

Then I should have ground on pin 1 for only two seconds then it drops (no signal from ecu)?

 

Correct.