MEP-804A - intermittent cranking, no starting

[Ray W]

Tested the MPU per the manual.

when dead cranking, manual says look for 800-900 OHM at wire 147 & 148
I got 701ohm

When dead cranking, manual says look for 2--3v at the same spot.
I got 2.5v

With mine being ground off a little, I'm going to put in a new one, its $20 and Ill know it should work properly.
Then Ill go from there...

 

[Guyfang]

The best way to reinstall it is to screw it in till it bottoms out, then turn it out 3/4 turn, (I do it 1 compleat turn because I have also joined the multitude of folks who ground one off). Then, lock it down lightly. Do not rehook the wires. Have someone else turn the gen set over with the S10, while you measure the AC out put of the MPU. 2.5 VAC is ok, but 3 VAC is about best. Get it right, lock it down, tight. Then test again!! OK? re hook the wires up.

 

[Ray W]

Im getting voltage of 2.5v ac when dead cranking. The manual says it requires 2-3v ac.
Im not getting the required OHM of 800-900 per the manual. Im only getting 701ohm.

 

[Guyfang]

Try to adjust it to 3 VAC and then try starting it.

 

[Ray W]

Thinking this one is too far gone.

 

[Guyfang]

Roger! Get another.

 

[Ray W]

New MPU arrived today. (MSP6729)

Fresh out of the box on the shop counter, the MPU tested at 323 ohm. Hmm...

In the 804A at wire 147c & 148c(both disconnected), it tested the same.
Hmm...

It also tested at 3.1vac when dead cranking.
Ok. Only .1 over spec.

Anyone think I got a bad or incorrect MPU? Vendor specifically listed 804A in his ad.

Spec says it should test at 800-900ohm.

HOWEVER, I’m sure I got one small spurt of fuel at some point because i have been checking one of the cylinder lines and it was wet where it had been dry previously.

Slowly getting there...

 

[155mm]

Still no start?

 

[Ray W]

Can’t even get a puff of white.
ive gotta wonder if the MPU I ordered didn’t meet spec.
The TM says I should be getting 800-900ohm.
I only get 323ohm.
I ordered the MPU noted throughout SS for this unit.
when this unit was reset, it left at 2.6 hours; which is pretty close to when I bought it and it has never started for me.
Frustrating.
I’m reading the TMs on my own and doing the research; but clearly missing something.