1g Fuel pump relay Bypass How to do it?????

[TERBOLASER]

hey i need to bypass my fuel pump relay so that the fuel pump is always on when the key is in the start and in the on position. i have a ecu that has caps replaced and only damage is it wont turn on the fuel pump relay so if i by pass it no more problem and i can turn my car on. tanks for the help i hear there is a schematic.

 

[steve]

http://www.taboospeedshop.com/wiring.htm or the FSM.

You should have the ECU fixed since it's a safety feature that the ECU controls the fuel pump after the starter is disengaged. The ECU turns the pump off if the engine dies to avoid a fire hazzard.

You'll note in the wiring diagram that pin 7 on the MPI relay controls one of the coils to activate the fuel pump. You need to ground this pin when you want the pump on.

Steve

 

[TERBOLASER]

thanks
so much man you trueley deserve the title of wise man for having all this random seemingly useless knowledge of dsms . which most would think is highly un necessary yet run to you when they need aid Thanks alot bro.

 

[TERBOLASER]

ohhh yeah man WHAT TYPE OF FIER HAZARD are we talking about ? just basic fuel cause i thought your fuel pump is on when the key is in the onposition but i guess not and what harm could com if the pump is on with motor off i mean willit build up to much pressure and pop sumthing or what.

 

[steve]

Anybody who's owned a DSM for a few years has all sorts of random knowledge. In my case I've owned it since new and you need to know this stuff to survive.

What happens if you do this bypass and the engine starts on fire? Normally once the engine stops running the ECU turns the fuel pump off but it can't do that now so it will continue to pump fuel until you turn it off.

Whoever fixed your caps should have fixed the fuel pump control circuit too.

Steve

 

[sirspoolalot]

what if you have some sort of on/off switch attatched to the re-wiring that you do? would that suffice?

 

[steve]

what if you have some sort of on/off switch attatched to the re-wiring that you do? would that suffice?

Suffice for what?

People can't figure out how to turn off their ignition if the throttle jams open your not likely to remember to turn off the fuel pump. If the car burns and hurts somebody you'll be liable if you have modified the control of the fuel pump to disable the factory safety equipment.

The point of this thread is that you should find the root cause and fix it not bandaid a problem because you can't figure it out. If it's a ECU problem activation the pump then get it fixed because it's likely the same problem unchecked will cause the ECU to fail when your in the middle on nowhere or on the highway with a semi full of swine tailgating you. You don't want to be up to your ears in pig shit.

 

[TERBOLASER]

steve of the dsm wise. its been a while since i asked that question. i never actually did what we were talking about because i read and understood the fire hazard. after going some years doing pro drag racing in NC. I look back at this and realized to me me its akin to building a drag car with out master shutdown switch and having a throttle with out a return spring. or an ecu that isnt set up to cut all fuel(* or most) on deceleration. I have seen a few cars get stuck wide open and go right off the track into the sand traps or net doing this.

Steve is right dont band aid fix it. unless its a dedicated race car. even so when i build cars particularly my drift AE86 I designed my circuits with logic control.. in example the ecu switch must be flipped first which not only turns on the ecu but then so long as ecu is on and running the car the fuel pump can be active. if conditions are met and the engine is killed then fuel pump off.

 

[TrevorS]

hey i need to bypass my fuel pump relay so that the fuel pump is always on when the key is in the start and in the on position. i have a ecu that has caps replaced and only damage is it wont turn on the fuel pump relay so if i by pass it no more problem and i can turn my car on. tanks for the help i hear there is a schematic.

The OE 1990 GSX uses the ignition switch to initially activate the fuel pump (I have the wiring diagram). The ECU turns it off again (if the ECU fails to turn it off there is a failsafe timer). As mentioned, having your pump always on with the ignition switch is a definite safety hazard. I'd get the ECU repaired rather than take such an unnecessary risk.

 

[steve]

The OE 1990 GSX uses the ignition switch to initially activate the fuel pump (I have the wiring diagram). The ECU turns it off again (if the ECU fails to turn it off there is a failsafe timer).

You got part of how the circuit works.

There are two coils to activate the relay for the fuel pump.

One is connected to the starter circuit. While you are running the starter the relay is activated and once you stop that coil is deactivated.

The other coil is connected to the ECU. When the ECU sees the engine running (CAS pulses) it turns on the pump (which may already be on) and resets the timer but if it doesn't see the engine running it checks to see if the timer has expired and turns the pump off if it has.

Some people report that their pump "primes" when you turn the ignition on but there isn't any code to do that. What is believed to happen is their CAS glitches on power up and the ECU fires off the fuel pump until the timer expires.

 

[TrevorS]

Thanks ! I had a dead ECU winter 2007/2008 (power supply burned up) and when I attempted to start the car, I could clearly hear the pump kick in, but only for perhaps 15 seconds (not measured). I was seriously relieved when I installed a rebuilt ECU in March and the engine came to life !

 

[sirspoolalot]

If i were able to find a new ECU for a 1st gen, the only problem is that I have DSMLink. I didn't put it in, i bought the car with it in so i don't now how to take it out / put it in the new ECU. is it extremely simple? or something i should have a pro do? Would an ECU from a junkyard be acceptable because I don't have the money to buy a new / slightly used ECU.

 

[steve]

I suggest you stick to your other threads to resolve your problems. Posting here just confuses things.

 

[TrevorS]

If i were able to find a new ECU for a 1st gen, the only problem is that I have DSMLink. I didn't put it in, i bought the car with it in so i don't now how to take it out / put it in the new ECU. is it extremely simple? or something i should have a pro do? Would an ECU from a junkyard be acceptable because I don't have the money to buy a new / slightly used ECU.

Shoot, man ! I wish I had the answers, but I've never had DSM link. I expected to pay $300 to have my old ECU rebuilt, but it turned out to be $500 since with a burned up power supply (it really stunk), it couldn't be rebuilt. I guess I can understand the argument, but it was a dissapointment nonetheless !

If you go back to the OE ECU, then you also roll yourself back to the OE MAF and 450cc injectors -- it's a package. If the OE wiring harness hasn't been tampered with, it shouldn't be hard to do, but from reading various posts, people have an unfortunate tendency to hack the begeezes out of their cars. You basically have to verify every associated wiring harness connection !

PS. FWIW -- the OE ECU seems to do pretty good with the 2G MAF and 550cc injectors, but it's not really recommended without adding an aftermarket AFR controller.

 

[Th3Revreant]

My Search-Fu is weak this morning, so posting here to try and resolve a fuel-pump related issue(I think). Please delete post if it doesn't belong here. I just picked up a 90 Laser GS N/T. When trying to start the car, the motor wants to turn over but won't. The guy I bought it from says the car started to sputter while he was driving like the car had no fuel and then shut off. All cylinders have compression, I'm thinking it might be a fuel pump or bad relay? Any insight would be helpful.

 

[JusMX141]

Sure, start your own thread on the topic instead of highjacking another from 3 years ago to post your kinda-sorta-maybe-related question.