Do any of you MegaSquirt users know of settings in MS that control the fuel pump?

It seems as if my fuel pump doesn't come on when it should.

(the wiring is correct, I KNOW it isn't wiring, the board doesn't have any boviously visible trace issues, we have checked continuity through the whole system and it is either hardware issue or software)


direct question:

which settings for the MS will cause fuel pump issues?

MS has a few settings for prime time and etc. Dig around in megatune


What I did was I had a static fuel pump relay on my scirocco so that when terminal 15 was ctivated, it received power and ran consatnty with the ignition key on.

I made my own relay and etc, bypassing the factory junk.

That was #1, 2nd time I integrated it with the factory setup so it received signal when the hall sensor was signalling and turned on then and did not run with the motor off.

Even though the injectors are closed, they could leak etc.....

I know there is a time function when you turn the key on. Mine I set for 6 seconds. It won't turn the relay on ( ground the relay) until it see's a cranking pulse from the ignition. I think it was set at one second as a default.

YES! That is the setting that I screwed with and lost... where is it??

Gary, right!

Mine is set up with an outside relay, and it is supposed to activate when the hall sensor/VR sensor starts showing that the engine is running.

do you have MegaTune running on anything now? which area should I look? It's probably an obvious spot, but still not jumping out at me.

kind of like looking for a pair of sunglasses that are on top of my head... I get used to them there and lose them. know what I mean?

I'll look now. Give me a couple.

I think it was on the initial set up. I don't see it as a drop down. It's in one of the configuration tables. While your in there adjust the temp gauge so it goes higher. There is a write up on the forum on how to do it.

Yeah I understand and honestly the megatune interface is not very intuitive. It is slightly kludgy and the UI logically does not make sense at times.....

I have an old laptop somewhere with a working megatune install, but I cant find it at the moment. I think it is under the initial setup or possibly in the area with the priming pulse/cranking pulse stuff....

i agree that megatune is "kludgy". have you tried TunerStudio, very nice ui
http://www.efianalytics.com/TunerStudio/

So the fuel pump NEVER turns on?

If so, then it's a blown driver transistor in the MS or a wiring problem (I know you've checked!). I don't think there are any settings that will cause the pump to never come on. The prime pulse settings that others have mentioned only affect how long the pump runs after you turn the key to the on position (before starting).

Ron, That's one of the pieces of software I use. =o) I go back and forth between the two; the megamanual has screenshots from MT that I use to find the settings I am looking for in TS. They both have good points and both have annoying "I haven't figured that out yet" type points.


MightyOhm; I didn't assemble mine. I have access to test DVOM, and solder gun, etc...

nothing on the board had any visible damage, but that doesn't mean anything. We also checked continutity with the DVOM as we traced out as far as we could on the board.

Bad Relay?? Mine that came with my relay board are all made in China. . . If you're not using an idle stepper in your system, then you have one of the three unused. Swap them.

all external Relays are fine. I can ground the relay to the chassis (what the MS unit does in a sense) and the fuel pump spins up.

Do yourself a favor and bypass the MS circuit entirely wire it so your fuel pump runs constant while the key is switched on.

This way you can get it running/started and then workout the bugs.

I found this easer, like I said I eventually went back so my hall sensor signal activated it and etc but short term it was fine with fuel being pumped while the key was on and it not running.

the injectosr being electric will nto open or leak unless they are damaged.

I have alligator clips by passing the MS right now... lol

while I'm looking for an answer to my question. =o)

It definitely sounds to me like the MS is not switching the fuel pump line correctly. If you connect a test light from 12V to the fuel pump output of the MS, it should turn on for a couple seconds when you turn the key on. Are you using a relay board?

No relay board, the MS fuel pump wire is wired to my own relay that I mounted.

No such luck with the test. =o(

do you know which parts of the board hardware I should look at?

Yeah, but I need to know what Megasquirt version you are running first. V3 board or V2?

version 3

The fuel pump driver transistor is Q2, it should be labeled on the board.

Have you checked the wiring to the Megasquirt and are you sure the Megasquirt is getting power (ie. it shows up with valid sensor readings in Megatune)?

Thank you for the diagram.

other than the fuel pump, I've had my car running from this MegaSquirt box. =o)

I found this. In case anyone else is looking and comes across this thread and needs to know where the Q19 transistor is physically located on the board.

http://www.kilowattclassroom.com/Archive/AN0007.pdf


and a link I found for testing transistors...

I will check my transistor and get back to you.