Wargasm

Hello,
Is it safe to run the fuel pump in high mode all the time by bypassing the fuel pump relay?

Thanks,
Brian

Blackbeast

I would assume it's safe because many people bypass it by feeding the 12-13V power directly from the battery.

Timmy

Mahjik

iTrader: (1)

From reading the previous posts on the subject, it's safe but will wear out the fuel pump faster.

I don't believe you'll burn the pump out in a matter of weeks. You'll probably just shorten the life of the pump by a year or two...

matwey

I've seen the other threads, but how would you do about doing it exactly, and aside from potentially eliminating the 3k hiccup, what would be the advantages?

Wargasm

Mahjik, That is my feeling as well.. if the pump lasts 5 years instead of 10 or 4 instead of 6... who cares... I'll just buy a new pump every 2 or 3 years and treat it like a wear and tear item like brakes or clutch..

Matwey, I am doing it to try to make my fuel system on my single turbo setup work more consistently. I think I'm having an issue where when I set my aftermarkted regulator up to work right in "low" mode, it makes too much pressure when it kicks into "high" mode. (I have an electronic fuel pressure gauge... so I can see this happening). Anyhow, by simply running in high mode all the time, it will hopefully be easier to work with.

There are a few ways to do this...

One is to install a relay in the trunk near the fuel pump. Have the relay triggered by the wire that now runs the pump. Then, run new heavy gauge wire from the battery directly to the relay and fuel pump. (use a fuse too!). When the car turns on the pump, it trips your relay which supplies voltage to the pump over the heavy wires.

Another way (the way I'm trying it first) is really simple (at least for a 3rd gen, don't know about others). In the nose of the car, there is a relay box. One of them is the fuel pump relay. Take this out and connect the appropriate two pins together with a jumper wire. You can buy male spade connectors at Radio Shack for like nothing, and just use a piece of thick wire between them and you're done! Easy to do, and easy to reverse.

Brian

DamonB

Unfortunately the ecu knows the relay is unplugged and even though the engine light doesn't trip, the ecu gets pissed off and goes into limp mode. You'll have to jump the wires under the relay so you can leave it in, or put an appropriate resistor across the relay socket's coil terminals while jumping the 12v terminals.

Wargasm

I jumped the relay ping yesterday and went for a drive...

My fuel pressure was much more consistent, and some hesitation that I was getting after installing the 1600s seems to be gone now.

The car didn't seem to be in limp mode, but then again, I have a PowerFC, so maybe that doesn't apply there. It had no problems making full boost and so on.

Damon (or someone else), do you have good evidence that this will trigger limp mode on a PowerFC? It's trivial to put a resistor in, so maybe I'll do that anyhow just to be extra safe...

Brian

Blackbeast

When you jump the 2 pins on the front fuel pump relay, wouldn't that make the fuel pump constant on?

As for pump not lasting by feeding direct 12V, it's trivial and I rather change pump every 3 year than changing motor every year due to fuel starvation.

Timmy

Wargasm

Jumping the fuel pump relay does not make the fuel pump run all the time because the circuit opening relay is still working. This item is turned on/off by the computer to determine if the pump runs or not.

Brian

DamonB

I don't know for sure about the PFC, but if you didn't have any trouble than I guess it doesn't care. The stock computer goes into limp mode if you pull the relay and run the car. Just plugging it back in won't fix it; you have to clear the ecu.