Wiring gurus needed

[familyMAN]

I will start by saying, "I HATE WIRING". Okay now that we have that out of the way....

Components....AEM Series 2. Hotwired fuel Walbro 450 (e85) pump. Cut wire on resistor to bypass low speed (stealth 316.) I also had the resistor unplugged with the jumper. No difference.

So here it is....strange one......MFI relay acts up a lot. Sometimes it clicks over and over with key on and primes my pump over and over. Other times, nothing. No prime, so no start. I have also had it just stop my fuel pump while driving. That really sux.

I replaced the hotwire relay. No change.

Here's where it gets really strange.....So I was out messing with it today trying to get it to repeat and I discovered very odd behavior.....If I sit in the car with doors closed, it will 30-40% of the time not click and prime and when it does it once, it doesn't want to prime with repeated attempts, UNLESS...I open the driver door. Primes on the next try. I was able to repeat this behavior MANY times. WTF? If I leave the drivers door open, it has yet to not prime.

Other background. I had to repair a couple of broken wires in driver door jam. Sometimes my windows don't want to roll back up. Maybe wiring related still, but how does window wiring affect MFI wiring????

Help. I HATE WIRING.

[Boost4VR4]

I will tell you one thing about the Mitsubishi wiring. IT SUCKS. They did a very bad job with improper ground wire sizes and splices everywhere, even out of the factory. Can you test the battery first then can you bench test the MFI relay and rule it out first? MFI relays typically do not go bad unless they get over-voltaged. The window wiring would be pulling voltage away from MFI relay as the window regulator is sharing the same ground. Thank Mitsubishi for that one.

[Jimvr4]

I was going to suggest the alarm system but all that does is kill the starter relay - nothing to do with the fuel pump.

The door switch is the only thing that changes with door open or closed and this switch only goes to the ETACS box. But no stock connection between ETACS and the MFI relay.

[familyMAN]

Battery voltage is good. I monitor through AEM (matches multimeter close enough), but I can check again with multimeter.

How do you bench test MFI relay? I really think it's something different and will be annoying to track down. Considering wiring the hotwire relay with a ignition switch to turn it on whenever ign is on.

[familyMAN]

I was going to suggest the alarm system but all that does is kill the starter relay - nothing to do with the fuel pump.

The door switch is the only thing that changes with door open or closed and this switch only goes to the ETACS box. But no stock connection between ETACS and the MFI relay.

My stock alarm has gone weird on me a few times (may be related since it was because of the driver door being unlocked/opened). Couldn't shut it off no matter what I tried. ('92 so key only). Had to drive it home honking/blinking and pull battery terminal when I got home. I have no issue disabling it completely if that eliminates any issue, IF someone can babystep me through it....I hate wiring...

[Boost4VR4]

Battery voltage is good. I monitor through AEM (matches multimeter close enough), but I can check again with multimeter.

How do you bench test MFI relay? I really think it's something different and will be annoying to track down. Considering wiring the hotwire relay with a ignition switch to turn it on whenever ign is on.

Right, but the MFI relay flips over signal voltage and since the hotwire kit gets signal from MFI relay, this would cause the pump to sometimes not prime if the MFI relay doesn't click over.

[familyMAN]

Right, but the MFI relay flips over signal voltage and since the hotwire kit gets signal from MFI relay, this would cause the pump to sometimes not prime if the MFI relay doesn't click over.

Not sure I am mopping what you are spilling. ? kindergarten it for me

I understand the MFI is what signals the hotwire relay. Don't understand why the MFI not kicking sometimes and how the hell it can be related to my door being open.

[Boost4VR4]

Not sure I am mopping what you are spilling. ? kindergarten it for me

I understand the MFI is what signals the hotwire relay. Don't understand why the MFI not kicking sometimes and how the hell it can be related to my door being open.

I think I misinterpreted the last sentence in your OP. I think I got it now. It primes with door open. So what I can tell you is that the grounds in the harness are crap. They spliced into a lot of stuff. If you have door chime, or lights, etc, those would all be contributing factors when opening the door that could explain why it works with the door open. When the door is open, the positive voltage is passed and the ground is the body of the car. The MFI relay takes the same path so when the door is opened, circuit is completed. The MFI relay, IIRC, has another ground wire that you ground to the center console...

[Jimvr4]

Eric, try this. Unscrew the door switches and save the screws in a baggy. They ground through the screw to the body so removal means the car always thinks the doors are closed. If this works then replace the door switches with new ones.

[sublime_whatigo]

^This, well at least clean the metal and try again. If this fixes it you have bigger issues but worth a try. BTW how are you priming the pump, through the diagnostic port/aem or cycling the key?