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-   -   502 MPI wont start!!! (https://www.offshoreonly.com/forums/general-q/213387-502-mpi-wont-start.html)

stevesxm 07-23-2009 02:54 PM

if the kill switch was off the plugs wouldn't get wet because the efi would be dead as well. if you just change the plugs it will start for a few minutes before it washes them out again.

Panther 07-23-2009 03:39 PM

I believe it cuts ignition, not the power to the computer but I could be wrong. It should still crank over but no spark.

Is this your boat? Wallin is in sweden??

tomas_wallin 07-27-2009 03:30 AM

It has a nice strong spark so it's not the kill switch.

I haven't replaced the plugs but took them out and let them dry out and put them back. The motor made one single attempt to fire and then went back to the dead...

tomas_wallin 07-29-2009 04:25 PM

I got it running, since there's no kill switch etc I had a hard time cranking without ign to clear the plugs but when I got that taken care of it started like a champ (after a while...)

Altough it's behaving pretty weird. When I move the throttle forward nothing happends and then everything happends at once, WTF?! It still won't rev over 2000rpm under load and it's very lame from idle and up.

The scan tool guy is coming on friday so if I don't come up with anything until then he gets to earn some money...

It beeps twice when I switch the ign on, if that might be anything?!

stevesxm 07-29-2009 05:05 PM

that sounds everything like the throttle position sensor or harness

tomas_wallin 08-12-2009 04:19 AM

The scan tool showed no error codes but the idle vacuum was at 85mmHg and should be at 50-60mmHg.

The IAC was at 140 (fully open?!) and the intake temp was at 95F and increased to 96F when we increased the idle. The temp should go down with the higher air flow but increased 1deg instead.

Might be an intake valve not sealing correctly? I unmounted the plenum and found two broken gaskets that I replaced but no or maybe very little difference but still not revving more than 2000 under load.

I tried increasing the timing (had no timing light) just a tad and it revved to 2500 under load instead of the 2000 before.

I'm going to check the timing today!

tomas_wallin 08-12-2009 12:04 PM


Originally Posted by tomas_wallin (Post 2930214)
The scan tool showed no error codes but the idle vacuum was at 85mmHg and should be at 50-60mmHg.

The IAC was at 140 (fully open?!) and the intake temp was at 95F and increased to 96F when we increased the idle. The temp should go down with the higher air flow but increased 1deg instead.

Might be an intake valve not sealing correctly? I unmounted the plenum and found two broken gaskets that I replaced but no or maybe very little difference but still not revving more than 2000 under load.

I tried increasing the timing (had no timing light) just a tad and it revved to 2500 under load instead of the 2000 before.

I'm going to check the timing today!

I couldn't get it to start today :( Put the batteries on the charger and will try again tomorrow...

tomas_wallin 09-08-2009 12:55 AM

The problem was solved. It's very wierd since it started and ran fine before it was mounted in the boat - but the timing was way off, kind of like one cylinder... Now it runs perfect :)

Thunderstruck 09-08-2009 07:43 AM


Originally Posted by Thunderstruck (Post 2915047)
Is the distributor set correctly? How did you set the timing?



AhhhA????

tomas_wallin 09-08-2009 11:09 AM


Originally Posted by Thunderstruck (Post 2948101)
AhhhA????

Yes, I know...

I was only helping a friend out and the timing was supposed to be correct...


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