KickItOut

My car randomly shut off in idle and would not restart. Everything turned over, just didn't start. Previous owner bypassed the Fuel Pump Ecu. As of now, via jumping relays, I know that the fuel pump does still work. I replaced what I though was a blown efi relay for the fuel pump. (Big Metal Relay in the fuse box)

I have narrowed it down to the relay is not being flipped, only getting 8 volts to the relay. Shouldn't it be 12? Again, if i jump this relay with a piece of wire, it works fine. Any ideas or solutions?

turbodremz

iTrader: (18)

Sounds like the fuel pump ecu was not bypasses properly. And yes you are correct, the relay should be getting 12v.

Check the fuel pump ecu to see how it was done, eliminate any butt-connectors or splicers, and solder the wires for the jump.

KickItOut

Right now, the wires are connected through a butt connector. The previous owner did it but it appeared to be fine. Also, are you sure about the bypass being the problem. Because when we jump the fuse box relay with a wire, the fuel pump turns on, leading me to believe it's not the bypass.

turbodremz

iTrader: (18)

It could be something other than what I stated, just thinking out loud. I would ditch the butt connector, and solder the jump though.

So the issue then is sourcing why your only getting 8v at the relay. Now the FP ecu is pulse controlled at 5v+/- depending on engine load from idle, and IIRC primes the pump with a mere 2.5v signal, but its still a 12v system. Technically, the fuel pump should run at 8v no problem, from the FP ecu, but I would assume by your situation that 8v at the relay is a bit low.

Have you checked voltage at the fuel pump ecu when priming/cranking?

edit: ^^ Not the voltage at the ecu, but the voltage at the pump coming from the fuel pump ecu.

KickItOut

I need to clear up tho that the pins for the fuel pump relay is getting 12v to go to the pump when jumped but the other pins that switch the relay on is only getting 8v so I'm wondering if the only 8v isnt enough to switch the relay on


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turbodremz

iTrader: (18)

Oh, ok I see what your saying. I over analyzed that one, sorry. 8v will close the relay.

But that puts the fuel pump ecu 12v mod as the culprit provided Im thinking correctly. Although butt-connectors are a quick solution, they are never the best when compared to soldering. If by chance the wires didnt not fully crimp inside the connector, the plastic shielding may hold the wire in place, but there is a poor connection.

But I would still check voltage with the IGN on at the fuel pump ecu going in, and going to the pump, both when priming and cranking. That will narrow your search and eliminate my targeting of the 12v jump.