Sudden MJLJ failure?

pavel5 · Post by **pavel5** » Mon Aug 29, 2011 1:36 am

With engine running, we connected up the computer.... program opened but nothing - no rpm, no vacuum etc shown and the little green LED light on the MJLJ unit is off.

Checked the obvious power/ground connections and that the pins in the molex are seated properly - all OK.

The soldered connections on the board seem OK too, but I don't really know...

Can anyone give me a rundown of exactly how to check out the MJLJ board? It was working...

Thanks in advance - I want to get our old Willys running and passing Aircare asap!

Cheers,

Pavel

Post by **brentp** » Mon Aug 29, 2011 5:15 am

First thing you want to do is actually measure, using a meter, 12V into the power and ground connections into the Megajolt.

Can you verify power going to the Megajolt when the ignition is 'on' ?

pavel5 · Post by **pavel5** » Mon Aug 29, 2011 6:44 am

Thank you Brent... I'll check the voltage where the molex pins are soldered into the printed board tomorrow.

pavel5 · Post by **pavel5** » Sun Sep 04, 2011 10:43 pm

Sure enough, when the various 12 Volt inputs were checked a bad connection on the upper side of the board was found while the under side still had a properly soldered joint. In the picture, I have shown exactly where the re-soldering was done. Power (green light) is on now, but the engine won't start correctly and after stuttering a few rpms, dies...

I trust that it doesn't matter that the MJLJ is not in its protective casing.

Reset the Global settings: 6 cylinder engine, 2 degrees trigger wheel offset (the timing light reads 12 degrees when running on the Ford ECM alone (should be 10 degrees) ... but still no start.

Unplugged the MJLJ and the engine still won't start. Fuses to coilpack and Ford ECM seem to be fine, so the next step is to check relays... Sorry, thinking out loud here! Better check for spark... Did I super flood it?

Will report back...

trevil · Post by **trevil** » Mon Sep 05, 2011 10:48 am

Have you tried to start the engine without mj connected, if you do not have a hard rev limiter, if same symptoms occur, there might be something else wrong too.

pavel5 · Post by **pavel5** » Mon Sep 05, 2011 4:52 pm

Yes, with the MJ disconnected, the engine shows no sign of life at all, very strange.... I'll check some more obvious possibles and report back.

Pavel

pavel5 · Post by **pavel5** » Tue Sep 06, 2011 12:46 am

Success! The Willys seems to be running properly again. MJ computer readouts seem to be working...

It was a fuel starvation problem... squirted some ether down the carb and she sputtered back to life after a long crank... air in the line? water in gas? sticking float bowl valve?

Thanks for the help gentlemen!

Now on to getting her through Aircare!

Post by **brentp** » Tue Sep 06, 2011 5:14 pm

Great that it's working!