MEP-804A - intermittent cranking, no starting

[Ray W]

Hello everyone, newbie here.

Thanks up front for all of the manuals and information I have already read. Great site and has helped me immensely!

So I'm on my second MEP-804A. Very nice units.

Like most, I bought this unit at a GOV sale that stated it was "cranking" but not starting.

The unit: MEP-804A(2012 reset), 3 hours on meter, two new batteries with good connections, fresh diesel fuel added, very clean unit.

The issue: Unit will only intermittently crank, so I cant consistently get to solving the issue of it not starting. It seems to follow no pattern of when it will crank over or not. Pretty frustrating. I'll tackle the issue of it not starting one I solve issue one; as they may be related.

Actions by me to attempt a start:
Dead crank switch in "Normal" position
Master switch to preheat - about 20 seconds(cold here)
Master switch to prime & run Aux fuel(causes ticking from the aux fuel pump) - continue on to the "start" position
Master switch to Start position - unit will sometimes crank over, while other times only cause a single "tick" sound. (rarely cranks over, mostly the tick sound)

Note: I have checked every connection I can see. All seem secure and non-corroded.
Dead Crank switch is in the "Normal" position
Emergency stop switch pulled out and checks good.
Unit will crank over strong via the dead crank switch, so this isn't a weak battery issue.
Fuses all check good.
No Fault indicators noted.
DC Control Power breaker in.

Question: Would the MPU signal an error even if the unit is not cranking over? I haven't pulled it yet because I didn't think it would cause the unit not to crank over. Thoughts?

If someone could offer some advice, I'd appreciate it very much.

Ray W.
Chantilly, VA

 

[Coug]

Not sure on this unit, but I know on civilian generators you can get an MPU error if the unit thinks it's supposed to be turning over but doesn't.

If you are hearing a slid "clunk" when turned to start but it isn't cranking, I'd be suspecting the starter of having issues. If it's the "tick" sound it could be anything from a bad connection somewhere not getting voltage to the starter solenoid/starter or a bad relay. Combine that with not starting when it does crank, and I'd be looking at one of the safety shut down circuits or something like that that is preventing the voltage going from the starter switch to the starter solenoid.

One of the guys that knows a lot more about these units than I do should be along soon for better advice.

If you haven't downloaded it yet, the manual for this unit is in the TMs section, here's a link to the specific set for you.

All the TM's you need to work on the MEP-804A

This should be all the TM's you need to work on the MEP-804A generator set.

www.steelsoldiers.com

 

[Ray W]

Thanks for the advice, much appreciated sir.
I'm going to check the MPU whenever it stops raining here in Northern VA.
Something is preventing the starter from consistently engaging and I'll eventually find it.

 

[155mm]

Mpu is first culprit everytime on a no start, even if you know it only ran out of fuel. Ac voltage should be less than 3.0 but more than 2.0 vac

Hand primer pumps are notorious for leaking, failing to maintain prime.

intermittent cranking sounds like starter, attempt tapping on starter with small hammer.

 

[Coug]

Thanks for the advice, much appreciated sir.
I'm going to check the MPU whenever it stops raining here in Northern VA.
Something is preventing the starter from consistently engaging and I'll eventually find it.

The MPU only does it's job after the unit is cranking, as far as I know it doesn't do anything to the cranking circuit itself, so that isn't likely to be your no crank issue.

 

[Ray W]

Copy Coug and 155. Thanks.
I'll have to get it consistently cranking before I can go on the the non-starting issue.
I'll give it another shot this afternoon, then test the MPU using the dead crank, and get back.

 

[Guyfang]

The MPU only does it's job after the unit is cranking, as far as I know it doesn't do anything to the cranking circuit itself, so that isn't likely to be your no crank issue.

Hello everyone, newbie here.

Thanks up front for all of the manuals and information I have already read. Great site and has helped me immensely!

So I'm on my second MEP-804A. Very nice units.

Like most, I bought this unit at a GOV sale that stated it was "cranking" but not starting.

The unit: MEP-804A(2012 reset), 3 hours on meter, two new batteries with good connections, fresh diesel fuel added, very clean unit.

The issue: Unit will only intermittently crank, so I cant consistently get to solving the issue of it not starting. It seems to follow no pattern of when it will crank over or not. Pretty frustrating. I'll tackle the issue of it not starting one I solve issue one; as they may be related.

Actions by me to attempt a start:
Dead crank switch in "Normal" position
Master switch to preheat - about 20 seconds(cold here)
Master switch to prime & run Aux fuel(causes ticking from the aux fuel pump) - continue on to the "start" position
Master switch to Start position - unit will sometimes crank over, while other times only cause a single "tick" sound. (rarely cranks over, mostly the tick sound)

Note: I have checked every connection I can see. All seem secure and non-corroded.
Dead Crank switch is in the "Normal" position
Emergency stop switch pulled out and checks good.
Unit will crank over strong via the dead crank switch, so this isn't a weak battery issue.
Fuses all check good.
No Fault indicators noted.
DC Control Power breaker in.

Question: Would the MPU signal an error even if the unit is not cranking over? I haven't pulled it yet because I didn't think it would cause the unit not to crank over. Thoughts?

If someone could offer some advice, I'd appreciate it very much.

Ray W.
Chantilly, VA

Ray, try looking at the wires hooked to the S1, and make sure they are hooked up right, and tight. Nect, mesure from S1-7, to ground when sturning the S1 to start. What you want to do is hit a spot where the starter dosent start, just clicks. Thats when you want to see if the 24 VDC is at pin S1-7. If the set wont turn over, and the 24 volts is there, then the S1 is good. Then take off the top cover, and insure the K2 is tight. Then measure at the K2, pin X1. Measure if you are getting 24 volts at the X1, when you place the S1 in the start position. Test it just like the S1. You WANT to hit a spot where the starter wont turn off. See if the 24 VDC is there or not.

 

[Ray W]

Hi guys,
Thank you for all your replies.

After a holiday break:

Issue 1 solved. Non-cranking issue solved just by chance. The Cranking relay(k2) was the culprit. When my son was turning the S1 to the start position and I was checking wire connections, I accidentally bumped the k2 and the engine began cranking. I can repeat this consistently by tapping the k2 as the s1 is turned to the start position.
Solution: get a new cranking relay(SM50D8 or similar or possibly open it and clean(?)
If no, Anyone have a source for a new one?



Issue 2:
Fuel is not getting to the cylinders. It gets as far as the finger pump and filter, but it appears the Woodward solenoid pictured below is frozen; probably due to sitting 8 years after a reset. It clicks slightly when cranking but when I removed the nut cap and when I look inside the access hole I dont see any movement in the actuator.(no movement near the spring)
Any suggestions on how to un-stick it so the fuel will pass?





One step at a time...

Ray

 

[155mm]

I have cleaned up a few relays and made them fully functional again.
Verify k2 is grounded properly by cleaning paint off where the mounting bolts are.

the fuel shut off/throttle contol wont do anything until he mpu says the motor is turning, i would verify mpu is functional and adjusted properly.

 

[155mm]

Just a word of warning, if you remove that governor actuator, you will learn new wordy dirds getting it back together correctly, its a spring, a side slide movement and forward movement.. if I remember correctly.

also there should be oil behind the plate its mounted to, check and make sure there is oil, mine was empty

You can manually actuate the throttle from the hole you were inspecting, but it could run away so be prepared to cut the fuel line and watch it kato

 

[Guyfang]

Before fooling with the A6, (actuator) try testing, troubleshooting. Most A6's get changed for no reason. As stated above, start with the MPU. Then you have a good idea what to do.

It can not hurt to try and fix the K2, if its even bad. wires first, then ground. If it still acts funny, take it apart. The relay is in Epay. Use the part number and NSN to find it.

 

[robertsears1]

Ray, after you get it to crank consistently search for this thread about my 804a— 804a cranks but no start, suspect the solenoid on side of the injector pump. I was never able to change the title to say what it really talks about, the MPU.

Robert

 

[Ray W]

Ray, after you get it to crank consistently search for this thread about my 804a— 804a cranks but no start, suspect the solenoid on side of the injector pump. I was never able to change the title to say what it really talks about, the MPU.

Robert

Thanks all for the info.
18 degrees in VA this morning but I took out the MPU because I’m ready to get this solved.
Photos are below.
I think mine may have been misadjusted and the flywheel ground it off. I think it should more of a button on the end.
thoughts?

 

[Ray W]

This is a 2.6 hour reset done in 2012.
All of the pics I find show more of a button end on the pickup.

Where’s the best place to source an MPU and a K2?

 

[155mm]

It does look rubbed, i would get another for sure, but that one may still be serviceable. Did you test it before removing?

 

[155mm]

It can not hurt to try and fix the K2, if its even bad. wires first, then ground. If it still acts funny, take it apart. The relay is in Epay. Use the part number and NSN to find it.

Guy says k2 is on big e auction site,

 

[155mm]

Go to your local semi truck parts house, they will have the mpu, tell them, 2003 peterbuilt 379 vin 3d588760, 18 speed tranny speedometer sensor

or jazz hands the googler if you want to wait.

As long as the mpu is long enough, the threads are correct, any mpu will work, all a mpu does is create an ac voltage signal

 

[Ray W]

Roger.
Heading back out into the cold to test the current MPU.
If no go, will hit epay later on for the MPU and K2; I'm not in a hurry.
Thank you to all who offered advice!

 

[robertsears1]

It may not have worked with all of that junk stuck to the magnet. As was suggested, clean it, reinstall and see what you get. If the voltage checks out, give it a try. You will definitely need the heat today. If it is bled and working, you should start to see white or black puffs from the exhaust quickly indicating that it should start. Again, no ether!

Robert

 

[Guyfang]

Right off the top of my head, with the MPU in your hand, the Ohm mesurment should be between 900-1200 Ohms. Easyest way to see if its still good. Take your time reinstalling it. Or you too will join the multitude of folks who have ground one off.