Ms3 dead, randomly
 

Howdy,

car has been running great on the ms3 for over a year now without issue -- pulled in the garage the other night after a cruise with the wife (gapped a nice 5.0 on the highway...nice) shut it off, came back 2 days later and:

key on - no fuel pump prime, but radiator fans come on
No start, but turns over and lights/hvac works
Will not connect to laptop or tablet that I have always used, checked comm settings - no dice
Underhood fuses are all intact --- I would imagine main relay is fine since I have power everywhere else

Did some searching on the forum, there is 1 thread where similar event was described -- someone said firmware corrupted and I have to manually reset it? Not sure how to do this. But the OP never confirmed, last post states they sent it out somewhere but never returned for an update and I don't want to revive a 5+year old thread

I did swap out 1 of the small black fuses on the board with no change, someone said there are 2 but I couldnt locate a second? Any help here?

94 MS3pro, can't identify anything that "happened" to cause this

Update:

I got ahead of myself and swapped out a bad main relay... for another bad relay. Borrowed a known working one from Napp Motorsports and fired right up.

*solved, happily solved*

I had something very very similar happen yesterday. 1990 on MS3x. Driving down the highway, engine just straight dies, no sputter, just death. Can't restart. 10 minutes later, can restart, but only run for about 60s the dies. Each time it dies, MS3x connection drops, too. Lots of forum reading while waiting for AAA.

Try jumping GND and F/P in the diagnostic panel and see if your fuel pump primes. Mine did. I'm 99% sure that my fuel pump relay is bad, and that somehow the power for my MS3X relies on that relay, too, as my laptop is connected to the MS as long as those points are jumped. Seems weird. Now I'm just trying to figure out how to remove the damned relay to replace it.

it is under the hood in the box, labeled Fuel Inj and is a Denso B6S8 relay, poke around a little and you can find cheaper options than the OE denso replacement