Fuel pump toggle switch
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Fuel pump toggle switch
I have replaced both the fuse and the relay on my 87’ 924s I can get it to run with the relay in if I move it into a certain spot. Runs fine with a jumper. I’m looking for a more permanent fix I have done the cleaning and crimping of the connections on the DME relay and it works for a bit then stops working again. I would like to put it on a toggle switch I know I will need two switches for the two cables. I was wondering if anyone has done this before and knows how to do it. I was thinking of pulling the wires out of the relay board and adding extra cable to the fuel pump ignition and power then putting the switches on the center console. Just not sure how to do it. Any help would be awesome, thank you!
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From: Boulder, CO
Having the fuel pump run when the engine is not turning is what I call the "fireball mod". No particular reason. Oh yeah two of my brother's cars were destroyed by large fuel fires.
That's probably the reason.
That's probably the reason.
Three Wheelin'
Joined: Oct 2021
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From: Central MD & Southern WI - 89 S2 Megasquirt + Variocam
Sounds like you need a new relay? Or look at fixing the connections in the fuse box.
I wouldnt recommend trying to bypass these systems, focus on actually fixing them the right way
I wouldnt recommend trying to bypass these systems, focus on actually fixing them the right way
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I would like to but I’ve tried every fix I’ve found and I’m always back to the beginning with each one. It’s definitely a connection issue as the relay is good. I put it in a buddy’s 944 and it was working. I went as far as to pull the dash and trace my harness there is no other issue with the wires in the harness. I’m just at the end of my rope as I’ve been trying to fix this for going on 7 months now and nothing is working.
Three Wheelin'
Joined: Oct 2021
Posts: 1,849
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From: Central MD & Southern WI - 89 S2 Megasquirt + Variocam
Relays can be hit and miss sometimes because they are mechanical. Sticking one minute working the next. Really recommend a solid state DME relay from F9Tech as these are superior to analog relays.
Heres a few resources which will hopefully help you test and work through the issue -
1) bypassing the DME relay is the first step (as shown in the link below - very important) - if that works its a fairly good bet the relay is the issue.
2) also look at and test w multimeter the inputs/outputs to the relay as well using the diagram - ignition switch, power to injectors, ground via DME and ground from DME to fuel pump pickup, power from battery, power to pump.
If any of those arent working or have bad wiring/connections it will also cause the relay not to kick over and a loose wire or bad connection can give very confusing results sometimes. Test each of those inputs using a multimeter where the relay connects to the fuse box making sure you are getting power and ground where appropriate. Note that 87 sends power out to DME and injectors and is not an input (but should have continuity if tested). Youll want to test 86, 85, and 85b while also making sure you have continuity at 87b and getting 12V from 30 always. If any of those fail the tests I would suspect wiring.
https://www.clarks-garage.com/shop-manual/fuel-05.htm
Heres a few resources which will hopefully help you test and work through the issue -
1) bypassing the DME relay is the first step (as shown in the link below - very important) - if that works its a fairly good bet the relay is the issue.
2) also look at and test w multimeter the inputs/outputs to the relay as well using the diagram - ignition switch, power to injectors, ground via DME and ground from DME to fuel pump pickup, power from battery, power to pump.
If any of those arent working or have bad wiring/connections it will also cause the relay not to kick over and a loose wire or bad connection can give very confusing results sometimes. Test each of those inputs using a multimeter where the relay connects to the fuse box making sure you are getting power and ground where appropriate. Note that 87 sends power out to DME and injectors and is not an input (but should have continuity if tested). Youll want to test 86, 85, and 85b while also making sure you have continuity at 87b and getting 12V from 30 always. If any of those fail the tests I would suspect wiring.
https://www.clarks-garage.com/shop-manual/fuel-05.htm
Last edited by walfreyydo; Jan 24, 2024 at 03:56 PM.
