megasqirt fuel pump questions

[wildo105e]

I have been testing my megasquirt bit by bit now. I thought the MS gave out about 5 secs live to the fuel pump to build pressure and then shut of until cranking was sensed. My doesn't seem to do that. On megatune (bottom left of screen)it turns on the pump on ignition turn on and turns off after about 5 secs.
Or does it purely give live on cranking (which I have not yet tested).

Also does anyone have views on air valves a lot of the pinto turbos i have seen piccies for seem to have blanked off the valve and done away with it.

Cheers:thumb:

[muckerbarry]

im using a fairly old version of the MSnExtra code (about 2 years old now), but this is how mine works, when you turn on the ignition the fuel pump runs for 2 seconds, and then starts to run again when the engine is cranked.

Does the fuel pump run when the engine is cranked? if it does it may just be setting in megatune. if however the fuel pump doesnt run at all it may be a hardware problem. connect the megastim and check does the fuel pump led light, if it lights you may have a problem with your pump or your wiring, if it doesnt light there is a problem with your megasquirt.

i had to change the fuel pumpp transistor once before on my megasquirt board because the fuel pump would not run, but a faulty transistor is very rare so check everything else first.

by air valve i presume you mean the air idle control valve for cold running? if that is what you mean you dont really need it, its there to increase idle RPM until the engine warms up. you may or may not need it, i dont use it on my zetec with throttle bodies. I just have a slightly higher idle RPM when the engine is warm, about 950RPM when warm, and about 750RPM when cold (because idle increases as the engine warms up). If I used an idle control valve I could tune it so that it was 750RPM all the time, hot and cold, but I am happy to live with 950RPM when hot.

the best place to get MS questions answered is the msefi forum, if you have not already joined it do right away, they are and extremely friendly and will bend over backwards to help.

[wildo105e]

Cheers. I am going to try it on cranking this weekend and see if i get 12v from the pump feed. This will also feed the coil pack aswell.

I did test the MS feed to the relay and got nothing so cranking will be the real test if i get nothing then with a decent crank rpm then the ms is likely, but this prebuilt by extraefi so i am don't think this is at fault. We shall see:thumb:

Yes it is the air idle valve i meant. So i could disconnect this and tune it at a later date once i have the car running etc.

Thanks

[wildo105e]

<LI class=MsoNormal>If you have a throttle body injection (TBI) system, verify that there is a small squirt of fuel (equal to the “prime pulse”) when MegaSquirt is powered up (by turning the ignition key to run), and that no more fuel is injected until cranking starts. If this is not the case for your system, find out what is wrong and correct it.
Just found this in MS extra manual. Looks like i have some checking to do:confused:

[muckerbarry]

That’s right, I do, when I turn on the ignition I can hear the injectors click open and closed. this is normal, its a prime pulse just for starting the engine, my car always starts first tip of the starter, which I imagine is because of this prime pulse, but it can be turned off in megatune if you wish.


It works really well as I said, but if you have someone who is driving your car who doesnt know what they are doing, and they repeatedly switch on and off the ignition without starting the engine, they WILL flood it!

[wildo105e]

I have been looking into this over the weekend with no success. I contacted Phil at extraefi who built the unit. I also found out from the megasquirt forum the answer. The MS unit gives out an earth for the fuel pump not a 12v live as i assumed:wall: You live and learn. I will rectify tonight and see how we go.

Cheers:thumb:

[wildo105e]

Did the changes and guess what it works:thumb:. Just to add that Phil at Extraefi who built the unit came back quickly with a reply and was more than happy to look at the unit even though i have had it around 12 months before fitting:clap:

Now onto the next glitch:D

[alladdin]

glad your making progress , i started puting my ecu/relay board cable together this week, built the ecu a year ago !

[wildo105e]

Cheers,
I am getting closer to putting in some fuel and seeing if it will go. I have decided to go straight to wasted spark aswell and forget running on points. So I just have to wire the coil in.:thumb:

[alladdin]

old thread i know but just re-read it, the earth from the ms is for a relay coil operation, the relay then feeds 12v to pump.