MEP-802A no crank/no power

[polk738]

Hey guys I'm back again, this time I've got a MEP-802A with a no power/no crank issue that is confusing me a bit. This is what I know so far, batteries are good although I do have a Tesla jump box hooked up to the slave receptacle so it does have plenty of power. I've got nothing at S10 (Dead crank switch) tested the switch its okay and I have power at the appropiate terminals. No power anywhere when its set to Prime/Run, fuel pump doesn't come on, tested CR-1 thats okay- I did a test that kloppk sent to me awhile back for another generator and this is what I've got

S17 both terminals have 24V
CB-1 both terminals have 24V
S1 pins (2,4, 6, & have 24V
S1 pin 7 .6V in START
K12 (term 0V in START
K12 (term 2) .6V in START
K16 (term 6) 0V in START
S7 (term 1) 0V in START
S7 (term 2) 0V in START
K2 (X1) 0V in START

I do have power at the shunt MT-4 so I jumped it from the shunt to S1 pin 6 and was able to get the fuel pump to come on and have it crank when I turned it to start and this is where I'm at now, so my guess is I've got high resistance somewhere in between the shunt and S1, thoughts?

 

[Guyfang]

Have you ever seen this generator run right?

 

[polk738]

Have you ever seen this generator run right?

not to my knowledge but we've had so many it's hard to keep track of them all

 

[Guyfang]

What kind of S1 is in the set? If you can take a picture and post it. There are three different versions. Iit kinda sounds like you may have a bad S1.

 

[kloppk]

Sound like you are losing power between MT4 and S1-3
Try the following
1) Put Dead Crank in the NORMAL position.
2) Put S1 in PRIME/RUN and verify the fuel pump is NOT running. Leave S1 in PRIME/RUN.
3) Check for 24 volts at both big terminals on MT4.
4) Check for 24 volts on BOTH leads of CR1. Be sure it's CR1. The labeling can be misleading.

5) Check for 24 volts on S10-2.
6) Check for 24 volts on S10-3.
7) Check for 24 volts on both used terminals of S17.
8.) Check for 24 volts on both terminals of CB1.
9) Check for 24 volts on S1-2,4,6, & 8
10) Check for 24 volts on S1-3


Post up what you find.

 

[polk738]

What kind of S1 is in the set? If you can take a picture and post it. There are three different versions. Iit kinda sounds like you may have a bad S1.

That is what I originally thought as well but I just had a brand new S1 installed on it and still the same issue.

 

[2Pbfeet]

That is what I originally thought as well but I just had a brand new S1 installed on it and still the same issue.

Could you still post a photo of S1? Did you do the S1 installation?

As you know S1 has been swapped at once, it might be a reasonable idea to sit down with the manual, pull all the wires off, and rewire it.

All the best,

2Pbfeet

 

[polk738]

Could you still post a photo of S1? Did you do the S1 installation?

As you know S1 has been swapped at once, it might be a reasonable idea to sit down with the manual, pull all the wires off, and rewire it.

All the best,

2Pbfeet

I doubt that it is wired wrong, the tech who did it, is very capable and I trust him

 

[polk738]

Sound like you are losing power between MT4 and S1-3
Try the following
1) Put Dead Crank in the NORMAL position.
2) Put S1 in PRIME/RUN and verify the fuel pump is NOT running. Leave S1 in PRIME/RUN.
3) Check for 24 volts at both big terminals on MT4.
4) Check for 24 volts on BOTH leads of CR1. Be sure it's CR1. The labeling can be misleading.
View attachment 951506
5) Check for 24 volts on S10-2.
6) Check for 24 volts on S10-3.
7) Check for 24 volts on both used terminals of S17.
8.) Check for 24 volts on both terminals of CB1.
9) Check for 24 volts on S1-2,4,6, & 8
10) Check for 24 volts on S1-3


Post up what you find.

Hey kloppk, thanks for chiming in I really appreciate it this is what I have

Dead Crank in normal/ S1 in Prime/Run
MT4 both terminals 24V
CR-1 right pin 24V left pin .9V
S10-2 .9V
S10-3 .9V
S17 both terminals .9V
S1 2,4,6, & 8 .9V
S1-3 .9V

Well it appears that the CR-1 diode is shorted but I am sure that I checked it before and it was fine, unless I accidently checked the wrong one, it's possible. Or I possibly shorted it when I jumped the MT-4 terminal to the S-1 to see if I could get any power. Thoughts?

 

[kloppk]

It looks like CR1 is bad.
To verify that put a jumper between the two leads of CR1 to bypass it.
See if the generator crank properly.
If so CR1 needs to be replaced.
It's a 1N5406 3amp diode.
They fail fairly frequently.

 

[polk738]

It looks like CR1 is bad.
To verify that put a jumper between the two leads of CR1 to bypass it.
See if the generator crank properly.
If so CR1 needs to be replaced.
It's a 1N5406 3amp diode.
They fail fairly frequently.

Yep that was it, hooked my jumper wire up to it and it fired right up, I apologize guys I should've paid better attention when I thought I had checked CR-1, this was an odd fault, I originally had 24V going into the respective pins of S-1 but now that has changed for some reason, lesson learned I guess. I appreciate everyone who chimed in, thank you for your help

 

[kloppk]

... I originally had 24V going into the respective pins of S-1 but now that has changed for some reason...

That's the usual failure mode/symptom of a bad CR1.
With no load it'll supply 24 volts. As soon as a load is applied the voltage drops to zero.
Many have had that same symptom and failure of CR1. You're not alone!

 

[Ray70]

Good work being persistent everyone! As soon as I first read this post I thought CR-1 but OP said it was good, so I immediately checked that off the list.
Just goes to show you that nothing can be taken for granted. Test...Test...Test...Test....replace....confirm