fuel pump issues with crazy resets

[kildea]

so i have msns-extra on a v3 main board, i've purchased and used the relay board and until now i've had good luck with things except for where i made mistakes ... i.e. it was not megasquirt's fault - so i expect this is another of my mistakes.

first thing to note, which will become relevant later, is that i have two fuel pumps. the intank is ipd's upgraded turbo pump, that i got a couple of years ago, it functions well, or so it seems to, the other is an msd inline pump, also appears to function, however it makes a good bit of noise.

so the problem arose suddenly, everything was going great and all of a sudden i started getting resets, the resets grew more frequent until i could not keep the car idling, they were occurring once every second or two.
so i shut the car off and got to doing some of the other crap that i had been neglecting while i let it cool off, when i restarted the car it was fine again until it had been running for a couple of minutes then the resets started in again.

so rather than continuing the narrative i'll list my findings below:

1. unplugging the inline pump while the resets were occuring stopped the resets, the idle smoothed out too in fact, i did not drive it though since the intank supplies limited pressure (i think) ... but the idle was great, better than ever actually.
2. i found that when i reconnected the inline pump the resets immediately resumed.
3. running only on the inline pump the resets continued.
4. after letting it idle for ~5 minutes on just the intank pump the resets began again.
5. letting the thing sit for a while (the engine cooled but only to ~85 deg c) i could restart it and the resets were gone ... after ~30 seconds they came back.

so i figure there is something hapenning with the fuel pump circuits maybe, where the pumps are heating and causing an issue, i'm not sure, i did not take measurements of the voltage/current at various times during the 30 seconds prior to the resets reappearing or once they started to occur more frequently, that would probably answer the question - ohmic losses in some part of the circuit? - i can do this next time i work on it this week, but in the meantime i figured i'd post and see if there are any suggestions or known issues to watch out for or to be aware of ... also, i'm not using the stock relay, i just have the pumps in parallel fter the fuel pump output on the relay board.

so ... any suggestions?

[crazy0000]

What does your voltage read on MS with the pump plugged in?(unplugged?)

Doesn't everyone say low voltage to MS causes resets? maybe you are draining the voltage when the pump is plugged in.

[linuxman51]

I forget how the relay board works, does it have a relay on it for the fuel pumps? If so have you exceeded the amps for said relay?

[wennstroma]

it has a relay for main switched power, fuel pump, and one for an on/off type iac. mine came with 30 amp relays.
Are the grounds for the pumps good? The ground for the main pump is under the back seat, they do lose contact sometimes.

[kildea]

the grounds appear to be good and the system voltage (batt) appears to stay ~12-14V
i will check the grounds again though, maybe they are heating?

it does appear to be progressive though, the longer the pump runs the worse it gets.

also, i have a 30 amp relay for my fuel pump, but a 40 amp relay that can be used in its place, i'll try this first.
would it help if i posted datalogs? i can gather these tomorrow.

thanks guys for the input.

[wennstroma]

Mine has the 30 amp relay, but I think I only have a 15 amp fuse for the main and pre pump combined. Seems unlikely that is the problem unless you just got a bum relay.

I would probably just focus on system/battery voltage and voltage drops through the power and ground cables to see if you're getting some kind of feed back causing the resets.

Maybe check the cables from the alternator and starter to the battery for voltage drops too, maybe its just the load from the pump causing the cables to heat up and making the voltage slowly drop. I see that a lot at work, its not unusual to see a car dropping 1-2 volts between the alternator and battery because of degraded battery cables.

[kildea]

Mine has the 30 amp relay, but I think I only have a 15 amp fuse for the main and pre pump combined. Seems unlikely that is the problem unless you just got a bum relay.

I would probably just focus on system/battery voltage and voltage drops through the power and ground cables to see if you're getting some kind of feed back causing the resets.

Maybe check the cables from the alternator and starter to the battery for voltage drops too, maybe its just the load from the pump causing the cables to heat up and making the voltage slowly drop. I see that a lot at work, its not unusual to see a car dropping 1-2 volts between the alternator and battery because of degraded battery cables.



yeah, i have a 30 amp fuse there, but either way i am leaning towards the heating-up of connections too.
the only issue is that i see no drops in system voltage, the batt voltage is high when the resets occur ... but not at their highest, i.e. they get higher (~15 volts at times) with no resets, but maybe noise like you suggest?
keep in mind i say this because of what the datalogs show, but i have not measured the voltage/current at the fp relay or grounds during resets, so i will check that first.
i also will check that the grounds are secure ... i have been thinking of redoing grounds withe straps and terminals, so one in the trunk that connects the battery and other bits such as the fp grounds, auto antenna, amplifier, etc. to the chassis; then another under the hood, connecting all grounds up there to one terminal block with straps to the engine and chassis.

but i'll check the fp grounds as you suggest first.

[chenz]

Fuel pumps can be very noisy, one of the suggestions I had while troubleshooting noise was to put a diode in the fuel pump negative lead but the direction I can't remember. All I was told is one way will kill the diode and the other wont. I assume with the band towards the pump as current flows from negative to positive.

when I installed my aftermarket fuel pressure regulator I did so the wrong way around and priming pulses would blow the FP fuse, it's a 15 amp. Perhaps with your 30 amp fuse, if the FP is drawing a lot of current it's causing some other trip before the fuse blows. Maybe try a smaller fuse and see if it blows?

It's my 2 cents. about 2 cents worth that is :)

[kildea]

:oops:hah, well so after ripping everything apart for the 50th frigging time and changing out for my spare megasquirt .... then switching back i found the problem - i'm an idiot.

it was the serial-usb <i>cable</i> ... left it unplugged when i switched the megasquirts back and found everything was fine ... inserted the serial cable -edit: inserted the cable to the ms's serial port - (not connected to anything on the usb end) and it started resetting again.

all better now, except for the second lc1 that pooped itself ...


so anyhow, looks like those things can be/get flakey ... just like they explain in the assembly instructions ... duh

[Karl Buchka]

It sounds like you're really sick of all the MS issues on your car. How about we just trade cars, straight up. You know how nice and smooth mine drives. ;-)

[kildea]

It sounds like you're really sick of all the MS issues on your car. How about we just trade cars, straight up. You know how nice and smooth mine drives. ;-)

you know that's what i'm thinking ... :-P

[kildea]

hah, no actually i was wrong, it was not the usb adaptor ... after some time tuning i decided to coil up the serial cable ... to keep things neet, right?


so anyway, after coiling the wire the resets recommenced ... so it looks like i had an antenna ... and since my ms BOX was bolted to the floor and the db9 cable shield connects to the box the antenna became part of a noisy ground loop.

how lovely, no?


so moral is:

don't ground your ms box!

[blkaplan]

hah, no actually i was wrong, it was not the usb adaptor ... after some time tuning i decided to coil up the serial cable ... to keep things neet, right?


so anyway, after coiling the wire the resets recommenced ... so it looks like i had an antenna ... and since my ms BOX was bolted to the floor and the db9 cable shield connects to the box the antenna became part of a noisy ground loop.

how lovely, no?


so moral is:

don't ground your ms box!

haha, thats pretty funny. Its odd how you could mess with it by changing stuff with your fuel pumps.

[kildea]

haha, thats pretty funny. Its odd how you could mess with it by changing stuff with your fuel pumps.



that's the thing, the inline pump i got from summit is loud, like to the ear, probably otherwise as well though :) ... and now that it's all over it starts to make sense.

i could get it to reset by quickly hitting the throttle as well.
it was the noisey components (rf noise of course) that were the reset triggers.