# Megasquirt fuel pump relay problem



## LooseNut (Nov 27, 2001)

So I just power up Megasquirt for the first time in the car today and turn the key. Megasquirts got power, widebands got power but the fuel pump....it's got power but it's turning on and off. The relay isn't staying on for some reason. I'm using all stock relays on the original relay board. I can hear the fp relay click loudly everytime it turns on and I had a fuel leak that sprayed fuel everytime too.








Megasquirt is powered from the original 12V that powered the digi ECU.
The fuel pump relay is grounded in the same fashion as stock. (Instead of the ground being connected to pin 3 of the digi ECU, it now connects to pin 37 of MS.)
The AEM wideband is powered by the +12 that originally powered the coil. There is no change if I disconnect this.
The Ford EDIS is powered by the +12 that originally powered the oxygen sensor. 
I've read something about the fuel pump relay needing a tach signal to stay on? Anyone know something about this? The only other thing I can think of right now is removing the capacitor connected to the power supply at EDIS. And double checking the zener diode at the ISV. If I turn the key with the MS ecu not plugged in, everything gets power but the fuel pump (because the relay isn't being grounded.)
So if it's not a wiring problem the relay is bad...but it's brand new.
If the relay is some type of "smart" relay, can I simply replace it with a regular one?
Thanks for input!


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## sdezego (Apr 23, 2004)

*Re: Megasquirt fuel pump relay problem (LooseNut)*

Megasquirt (Much like the stock ECU) only pulses the pump when you turn the key on for 1-2 seconds. ...and then powers the pump when cranking/running.

Shawn


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## LooseNut (Nov 27, 2001)

*Re: Megasquirt fuel pump relay problem (sdezego)*


_Quote, originally posted by *sdezego* »_Megasquirt (Much like the stock ECU) only pulses the pump when you turn the key on for 1-2 seconds. ...and then powers the pump when cranking/running.

Shawn

OK, so the initial priming is right but it keeps pulsing it for 1-2 seconds then shuts off for a second then repeats....without touching the key.


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## sdezego (Apr 23, 2004)

*Re: Megasquirt fuel pump relay problem (LooseNut)*

Sounds like either megasquirt is resetting for some reason, or indeed, a relay is bad. Could be the power relay to MS that is causing the reset or MS itself or possibly the fuel relay as you suggested.
You should be able to verify resets in megatune.


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## Pinepig (Jul 9, 2001)

*Re: Megasquirt fuel pump relay problem (LooseNut)*

MS will only keep the pump running if the engine is running, it relies on the tach signal into the MS to determine if the motor is running. 
I found this on a quick google search, it may help.
http://www.benzworld.org/forum....html


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## LooseNut (Nov 27, 2001)

*Re: Megasquirt fuel pump relay problem (Pigsdofly)*

At this moment I believe it may simply be a configuration issue with MS. The last time I had it powered with the stimulator I may have burned it wrong.


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## MikkiJayne (Jan 1, 2007)

*Re: Megasquirt fuel pump relay problem (LooseNut)*


_Quote, originally posted by *LooseNut* »_
I've read something about the fuel pump relay needing a tach signal to stay on? Anyone know something about this? 

Thats how the CIS fuel pump relays work http://****************.com/smile/emthup.gif When you power it up there's an initial prime pulse, then it stays off until it gets an ignition signal. That triggers a timer which turns on the relay. As long as ignition signals keep coming the relay stays on. Handy lil' things








The Corrado relay is just a conventional one, as you've no doubt figured by now








Regarding the MS - does is show the engine is cranking in MT?
Mikki x


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## LooseNut (Nov 27, 2001)

*Re: Megasquirt fuel pump relay problem (MikkiJayne)*

Man do I feel like a total noob. It was simply because MS wasn't set properly. I plugged the stimulator in tonight and sure enough, the fuel pump LED is just sitting there, turning on and off repeatedly. That fuel leak got me all frustrated and I couldn't leave the power on for too long without making a mess I kinda have an excuse.


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## ValveCoverGasket (Mar 20, 2002)

*Re: Megasquirt fuel pump relay problem (LooseNut)*

did you figure out which setting it was that caused the config error?

stim boards are great


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## need_a_VR6 (May 19, 1999)

*Re: Megasquirt fuel pump relay problem (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_
stim boards are great









They are!


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## LooseNut (Nov 27, 2001)

*Re: Megasquirt fuel pump relay problem (ValveCoverGasket)*


_Quote, originally posted by *ValveCoverGasket* »_did you figure out which setting it was that caused the config error?

stim boards are great










No, unfortunately i can't pin point what setting it was since I had gone through all the settings in Megatune and tried to make everything right before plugging it in. I just never opened up megatune after MS had power in the car. If I had, the problem would have been solved. I just had hopes of plugging it in and starting it up. When that didn't happen I got mad and left the garage.


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## ValveCoverGasket (Mar 20, 2002)

*Re: Megasquirt fuel pump relay problem (LooseNut)*


_Quote, originally posted by *LooseNut* »_
I just had hopes of plugging it in and starting it up. 

its standalone, not a chip









glad it worked out though


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