MEP 805A won't start

[steiner]

A little background first. I purchased this generator about 4 years ago and it ran when I bought it. It only has about 60 hours on the hour meter. It ran just fine last year when I tested it (ran for about 15 minutes) as this generator is used very infrequently. I recently wanted to make sure it was still working and when I started it, it would start and then immediately shut down. Both the under voltage and over speed indicator lights were lit. After resetting the fault indicator and resetting the overspeed, it would start but do the same thing again. I reset everything but this time when I started it I immediately switched the battle short switch to on and it continued to run for about 30 seconds and then shut down. I don't know why it shut down. While it was running I was able to notice the frequency meter was pegged at 62 Hz even though the frequency knob was turned all the way to the left. I figured this was a good indicator that their was a real problem with the overspeed. I tested the magnetic pickup as per the -24 manual. The resistance checked fine (1030 ohms) but the voltage while cranking was high (3.9 - 4.6 VAC). So I removed the sensor and found some small particles on it. I cleaned the sensor and reinstalled it. I adjusted it until the voltage was in spec (2-3 VAC). The problem now is the engine will crank but it will not start at all so I can't tell if I fixed the overspeed problem. There are not any fault indicator lights lit now. I have made certain that the fault indicator and overspeed switches have been reset as I did this several times. Any suggestions would be appreciated. Thanks......

 

[robertsears1]

I have 804s but no 805. At least on my 804s, if I don’t see puffs of white smoke from the exhaust after a few seconds of cranking, it is not getting fuel and it has almost always been an issue with the MPU. Try raising the cranking voltage on the MPU without grinding it on the flywheel since it would at least run there before.

Robert

 

[steiner]

Robert,

I set the MPU back to the way it was (around 4 VAC) and it still would not start. I did not notice any puffs of white smoke from the exhaust so I assumed I was having a fuel issue.

I first opened the drain on the bottom of the fuel filter to remove any possible water. I caught this fuel and did not see any water mixed with the fuel. I then opened the bleed air screw on the filter and manually operated the fuel pump but could not get air bubbles to stop. I probably pumped about 8 oz of fuel out of the bleed air screw. I went ahead and closed the screw and operated the manual pump until I couldn't feel as though I was pumping any more fuel. I then cracked the input line to the fuel injection pump and operated the manual pump to remove any air. Again, I could not get the air bubbles to stop. It would get better but I would still get bubbles periodically. Again I would guess I pumped about 4 oz of fuel and it still didn't clear up. I don't think I am sucking any air through a lose connection because when I have all fitting tight I am able to manually operate the fuel pump until it builds up pressure. It will hold this pressure and I don't see any fuel leaks. I am wondering if it is possible that the manual fuel pump might have a pin hole in the diaphragm and that is how the air is entering the system. I don't have any experience with diesel fuel pumps so this might not even be possible.

Any thoughts or ideas would be appreciated. Thanks.......

 

[jmenende]

Robert,

I set the MPU back to the way it was (around 4 VAC) and it still would not start. I did not notice any puffs of white smoke from the exhaust so I assumed I was having a fuel issue.

I first opened the drain on the bottom of the fuel filter to remove any possible water. I caught this fuel and did not see any water mixed with the fuel. I then opened the bleed air screw on the filter and manually operated the fuel pump but could not get air bubbles to stop. I probably pumped about 8 oz of fuel out of the bleed air screw. I went ahead and closed the screw and operated the manual pump until I couldn't feel as though I was pumping any more fuel. I then cracked the input line to the fuel injection pump and operated the manual pump to remove any air. Again, I could not get the air bubbles to stop. It would get better but I would still get bubbles periodically. Again I would guess I pumped about 4 oz of fuel and it still didn't clear up. I don't think I am sucking any air through a lose connection because when I have all fitting tight I am able to manually operate the fuel pump until it builds up pressure. It will hold this pressure and I don't see any fuel leaks. I am wondering if it is possible that the manual fuel pump might have a pin hole in the diaphragm and that is how the air is entering the system. I don't have any experience with diesel fuel pumps so this might not even be possible.

Any thoughts or ideas would be appreciated. Thanks.......

Lift pumps quite often go bad in my experience. It could be that you have built up enough pressure in the lines manually to start the unit but the fuel pump is worn or the diaphragm punctured that it cannot maintain a steady fuel supply. I believe your assessment is right and a bad diaphragm might be sucking air in from the crankcase.

In another note and this is worst case scenario. I was working on a 006a the other day that would start for less than 5 seconds and then turn off. It ended up being the fuel injector pump and had to rebuild it. After that no more issues.

Fyi: The john deere lift pump for the Mep 805a is the RE42211 and the gasket, which you might be able to reuse, is R520618.