importwarrior Posted April 13, 2008 Report Share Posted April 13, 2008 i have a megasquirt problem. everytime the car is turned to run and the fuel pump primes. the gauges in megatune seem to move as if there is some sort of interference while the pump primes. anyone else run in to this problem. it is driving me nuts. the car is wired properly as per the DIYautotune instructions. i do not know what else to do. i don't know how to trouble shoot this. any advice would be great. http://www.diyautotune.com/images/products/msharness12/msharness_pinout.gif Link to comment Share on other sites More sharing options...
Chad Posted April 14, 2008 Report Share Posted April 14, 2008 I can't help you with your problem, but I'd suggest bypassing it to see what happens. I have my pump wired to a relay switched by the ignition key, seperate from my EFI setup. Is the pump and EFi sharing the main power lead? DC motors can make a lot of noise. If shared, what size is the power lead? Link to comment Share on other sites More sharing options...
importwarrior Posted April 14, 2008 Author Report Share Posted April 14, 2008 (edited) i believe the lead from the ECU to the Fuel Pump white-red relay wire is 20 or 18 gauge. the power lead to the ECU is like 18-20 gauge wire. i will try hooking it up to a different power source. thanks Edited April 14, 2008 by importwarrior Link to comment Share on other sites More sharing options...
Chad Posted April 14, 2008 Report Share Posted April 14, 2008 Also, if the ECU isn't grounded relly well, they will be more susceptable to external noise sources. It's best to add atleast one ground lead to the frame/chsissis somehwhere. Link to comment Share on other sites More sharing options...
Shelby Posted April 14, 2008 Report Share Posted April 14, 2008 when you read things like such and such wire goes to fuel pump They do not mean to RUN the fuel pump with that wire,,,what they mean is it's a relay trigger not a power feed ,,,, trying to operate a fuel pump on the signal wire can distroy the ecu Link to comment Share on other sites More sharing options...
importwarrior Posted April 14, 2008 Author Report Share Posted April 14, 2008 (edited) i agree i have the fuel pump wire from the ECU going to the stock relay for the fuel pump. when it turns on, the relay for the fuelpump is kicked on and it gets power to the pump from the cars stock wiring harness. i have 2- 14 gauge wires going to the engine block for grounding. all my grounds from ECU and 02 go to the same spot on the block. hope i explained that well. thanks guys for the help. Edited April 14, 2008 by importwarrior Link to comment Share on other sites More sharing options...
Shelby Posted April 14, 2008 Report Share Posted April 14, 2008 geting the ecu set up to actualy work the fuel pump relay can be a little agrivateing so i'd sugest you do the start up and adjustments with the pump not connect'd thru the ecu,, once your all setup then play with the fuel pump relay operation Link to comment Share on other sites More sharing options...
Too Deep Posted April 15, 2008 Report Share Posted April 15, 2008 I was lazy and left the factory ecu in place to run the fuel pump. Never had a problem, and less wires to splice. Link to comment Share on other sites More sharing options...
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