MEP-016b won't stay running without holding throttle open

[maxf15]

First post... but yes, I did try to search for a similar problem first.

I recently bought two MEP-016b's at govliquidations. Brought them home, no parts missing, only one wire needed to be spliced with a wire nut. Added new oil, fresh fuel, followed the starting steps, cranked over fine, but neither would start. (0.2 hours on one unit - the one that needed the wire spliced; and 249.0 on the other.)

So, I slowly pushed the throttle linkage open (counterclockwise) while cranking and rattle, rattle... they jumped to life. As long as I held the linkage open about half way, they purred like they should, rpm's varied appropriately as I manually opened the throttle. But as soon as I let go, they shut off. Even tried pulling the throttle cable all the way out to max throttle, but it will not stay running at idle. Held towards the middle, all is fine. Let go and caput.

I'm not a certified mechanic, but certainly mechanically inclined. And I know it could be any number of things.

Hoping someone has had experience with something like this. Just trying to get these units to idle without manually holding the throttle; I'll fine tune afterwards.

Merry Christmas!

 

[maxf15]

Ok... update as of 10 minutes ago. I read about some fuel low switches causing issues, so I put more fuel in each tank and tried again. The older unit fired up, showed about 120V and I fine tuned the throttle cable to 60 Hz. AND IT'S RUNNING WITHOUT HOLDING THE CABLE OPEN! Yee-haw.

But the 'newer' 0.2 hour unit still won't stay running. It's almost certainly something preventing the throttle solenoid from holding the throttle open. (In the case of the older unit, it was the low fuel float switch.)

What else can cause that solenoid to not receive power or be commanded off? I can still hold it open and the unit runs great. (OBTW, I traced the previously split wire, and it was the hot wire to the starter. No wonder the unit only had 0.2 hours.)

Thoughts??

 

[ETN550]

Ok... update as of 10 minutes ago. I read about some fuel low switches causing issues, so I put more fuel in each tank and tried again. The older unit fired up, showed about 120V and I fine tuned the throttle cable to 60 Hz. AND IT'S RUNNING WITHOUT HOLDING THE CABLE OPEN! Yee-haw.

But the 'newer' 0.2 hour unit still won't stay running. It's almost certainly something preventing the throttle solenoid from holding the throttle open. (In the case of the older unit, it was the low fuel float switch.)

What else can cause that solenoid to not receive power or be commanded off? I can still hold it open and the unit runs great. (OBTW, I traced the previously split wire, and it was the hot wire to the starter. No wonder the unit only had 0.2 hours.)

Thoughts??

Congrats on your purchase. If you got one of the low hour tan units from Warner Robins they are good units.

Open the control panel box and flip up the lid to find the K4 relay on the left side circuit board. The relays are numbered on the right side of the relay socket so you may need to get your head in the box or use a mirror.

Turn the unit to the run position.

Open the fuel tank and move the lower float up and down with a stick and listen for the k4 relay. It shoud click as the float moves.

If the K4 relay clicks then the float, master switch, and relay are all good and there is a problem with the fuel control solenoid or the wiring. Using the wiring diagram in the box the wires from the relay can be traced to the terminal strip in the box and a meter can be used to make sure the k4 relay is putting power out to the fuel solenoid.

If all that is good then unplug the fuel solenoid and put a meter on the plug end and verify that it gets power as the float is moved up and down.

From these exercises you should be able to figure out if the soleniod, plug, wiring, relay, or float is bad. The master switch and the relay are rarely the problem.

I just fixed one where someone had bypassed the low float shutdown and the unit would not stop on low fuel. They had pulled a wire off the left circuit board and stuck it directly on the master switch, tying up everythng nice and neat so it was not obvious that there was anything wrong. Another common issue is the plug gets loose or worn on the solenoid. I've had several with the plug replaced with crimp on connectors that corrode or get loose. New connectors fix that.

When a wire is improperly located it takes a while to trace everything down. On more than one occasion I have found things wired improperly, including the exact thing you describe.

There is no end to the things that I find out of spec on these units when received from the military. I would encourage people to test all the functions and fix the stuff that has been jerry-rigged. These are excellent units when they are set up right and taken care of.

 

[goodguyzy]

Check the 7.5 amp circuit breaker. Mine had a bad one and if I remember correctly it was doing the same thing.

 

[maxf15]

Well, it's been 7 months... I had to move, and that took a little time before I could think about my generator. But I found out it was just the #2 fuse. One new fuse on F2, and voila! She runs like she should. One catch, I am not sure if the hour meter is functioning. The unit looks just as good as any I've seen, but I need to test the meter somehow. I don't think it's registering. Are the internal gauges AC or DC? And what should the reading be on the hourmeter if I put a tester on it?

Thanks!