MEP-803a Seems to be loosing power

[nextalcupfan]

A couple things off the bat, I bought the set Nov 2019 and it's run pretty well with only a few minor issues (oil leak at the valve covers that wont go away for example).
After I bought the set I replaced all fluids and filters including draining the diesel out of the day tank and adding it back a gallon at a time mixing with fresh diesel.
According to the sharpie on the air filter its last service was May 2006 at 98hrs. (My guess is to change out of the break-in oil)
Set had 150hrs on it when I bought it, now its around 280hrs.
Oil is AMSOil 15w-40 for pre-2006 engines, fuel is standard diesel from my local station with the correct amount of Archoil additive mixed in(AR6200 for Summer AR6300 for Winter).
Filters are all Wix brand.


So every few months I like to do a 100% load bank test on my 803a. This involves 3 Comfort Zone 5kw heaters hooked up to a sub-panel I installed on the set.
During this time I also test and set the Voltage and Frequency using my Fluke 17B multimeter, Voltage to 244V and Frequency to 60.0Hz at 100% load (which is around 62-62.5Hz at no load).

Before this winter however I noticed something, when I was turning up the Frequency to 60Hz it stopped around 59.8Hz and the knob got pretty hard to turn.
I checked and the arm the frequency adjust cable moves had hit its upper stop. I have NEVER seen it touch the stop before, I also have NEVER adjusted either stop (I know you really aren't supposed to except under specific circumstances).

First thing I tried was letting it run at 100% for 3 hours (I really only meant 1 or 2 but I kinda forgot about it....) to burn off any wetstacking, no change.
During this time I checked and the exhaust temps were roughly similar (I think one cylinder runs 10F cooler than the others but its been like that since I bought it).
Second was an oil change. Now I didn't expect this to change anything but it was due anyway.
Third was changing the fuel and air filters, I checked the air filter and it looked brand new still (only had 100-120 hours on it) so I didn't change it. I also checked for possible blockages in the air intake pipe for the airbox.
Both fuel filters looked fine but I replaced them anyway, still no change.
I DID NOT check the prescreen for the fuel pump (more on that later).
Forth was replacing almost all of the fuel return lines (the cloth covered ones that start leaking randomly).

Here is the latest video where I did a full load test, please check the description for timestamps.

Next is hooking up a fuel pressure gauge to see what my running fuel pressure is.
This one I'm quite curious about because my fuel pump does leak a small amount of diesel out of the electrical connection rubber plugs (where the wires go through the body of the pump).
Parts for this are coming in tomorrow(Monday) so I should be able to get you guys the numbers then, I also plan on checking the prescreen since I'll have it partially apart anyway.

What do you guys think? Did I miss anything easy in my troubleshooting steps?

 

[DieselAddict]

How many amps are you running during the load test? I suspect you are loading the machine more than you are realizing. In the video you are showing 125% on the meter with a resistive load. In reality that is more like 150% load. The load meters are set up for a power factor of 0.8 so they underreport on resistive loads.

Can you use a amp meter to see how much you are actually loading it up?

If you can put over 133% on the generator and it hold frequency, there is absolutely nothing wrong with it.

 

[nextalcupfan]

I load it to 13,000 watts resistive when I set the frequency. That's about 53 Amps.
I'll get you an exact number with an amp clamp when I run the test with the fuel pressure gauge hooked up.

But my issue is that it WAS able to reach 60hz (or a little more) at that exact same load last year.
Now it can't.
That tells me something changed and I want to find out why.

 

[DieselAddict]

Understood. My number one first line thing to do if an engine has any kind of issue making power (after inspecting for wetstacking and air filter issues) is to run it on known good quality fuel. It sounds like you are up on everything so your fuel may not be bad but I have to mention it. I had a guy bring me a generator last year that he said was hard to start and wouldn't make a lot of power. In the end it turned out he got a bad batch of fuel from his station. Not his fault. It does happen. Also, Winter blend doesn't make as much power as summer blend and since you are pushing it pretty hard, that can make a difference. Its not a lot of difference but it can be in the range of 5% less energy.

Has anything else changed? I assume you are in the same location and not at a different elevation?

Does the exhaust look the same?

One quick and easy test for fuel delivery is to pull the fuel return line and see if you still have fuel coming out when its under load. If you are returning a stream of fuel to the tank, its not a fuel delivery issue. A fuel pressure test is great but if you need to do a down and dirty test, pop off the fuel return line and verify you have flow.

Higher viscosity oil can rob some power. I'd say its possible but shouldn't really be that noticeable.

 

[jamawieb]

Shes running pretty good to me. The way that the governor is set-up your going to have adjustments overtime. The governor system is a cordination of springs, as they age, the stretch. Need to adjust your droop and your stop bolts on the throttle linkage. Dont mess with the adjustments on the fuel cut off solenoid. I understand your concerns but I think you are just breaking the generator in. Also how fresh is the fuel? Fuel collects water and wont burn efficiently. Ive also seen people put to much conditioner or fuel additives in the tank which wont let the fuel burn efficiently.

 

[nextalcupfan]

Fuel is definitely less than 6 months old, probably 3.
if the fuel pressure checks out I guess I'll mess with the droop and stop bolts. (I have the manual open to those adjustments)

 

[Light in the Dark]

I wouldn't mess with the droop setting unless the hertz are hunting. As Jimmy said, springs do sometimes elongate. Don't be afraid to make some small adjustments to the stop settings, to see if you can adjust back into range.

 

[nextalcupfan]

Ok this is going to be a bit long so buckle up.
I started off like I said and installed the fuel pressure gauge.
Off

Engine off Key On

Engine Running No Load

Engine Running Full load was 6.9-7.1psi
I believe pressure should be between 6.5 and 8psi so all good there.

Checked the fuel pump strainer.
Before

After cleaning with brake clean and compressed air.

It's not shown here but I did find a small piece of plastic in the strainer. It looked like a .5in section of either zip tie or twist tie.
Other than that all good here.

Generator behavior is the same, Frequency tops out at 62.5Hz and with approx 12600W (51A @244V) of load applied it dips to 59.5Hz.
So based on your recommendations I started adjusting the governor.
First I adjusted the droop to get the frequency drop as minimal as possible.
I did this by cranking the governor clockwise until the unit started hunting and backed it off 1 turn. (I actually started by backing off 1/2 turn but I could still get it to hunt under specific load circumstances)
Unfortunately while I was finding this sweet spot I lost count of my turns from start, but if you twisted my arm I would say I turned the droop screw clockwise around 2-3 full turns.

This made the max frequency drop to around 60Hz while on the max governor stop, so next step was adjusting the stops to get the manual specified range at no load (58-64Hz)
Unfortunately I couldn't get the lower limit quite where I wanted it because if I set it to 58Hz the arm would get stuck on the screw.
But eventually I got it set to 57.5-63.9Hz which is certainly close enough for me).
I should note I set this before my last droop adjustment of 1/2 counter-clockwise so it probably went up slightly on both ends.

Here you can see the change I had to make on the upper speed stop screw. Nut was left in its original position when I started and the screw was backed out approx 3/4in.
That seems like a lot to me....

Either way its set to spec now.

And here is a test video, please check the description for time stamps.

I will be keeping an eye on this to see if it changes in the future.

 

[nextalcupfan]

Ahh 1 more thing.

Here is the other adjustment (not sure what its called, fuel stop adjustment?)

I did NOT adjust these at all. Mainly because I don't know how.
I did see the solenoid was pulling all the way to the stop.

 

[Zed254]

I saw 71.4 amps at one point and a lot of 62.2 amp meter checks. This is a 52 amp machine in 120/240 volt. 52amps x 240 volts = 12480 watts......12.5Kw. It appears to me that you are overloading your machine. When I first bought my 803 I ran it hard to clean it out.....and it really didn't need much running. As I bumped up the amps it would slow down, start belching black smoke, then die: so I quit doing that. As others have said, your machine looks good to me.

 

[nextalcupfan]

I saw 71.4 amps at one point and a lot of 62.2 amp meter checks. This is a 52 amp machine in 120/240 volt. 52amps x 240 volts = 12480 watts......12.5Kw. It appears to me that you are overloading your machine. When I first bought my 803 I ran it hard to clean it out.....and it really didn't need much running. As I bumped up the amps it would slow down, start belching black smoke, then die: so I quit doing that. As others have said, your machine looks good to me.

Most of my actual testing was 51 A @ 244V for the governor droop.

Everything else was just seeing the generator could take the load and how the governor responded (trying to find potential hunting issues).
I have a 3-ton AC on my house and it hits the generator pretty hard (LRA is 77A)

Also keep in mind that 71.4A reading was on that leg only, the other leg would have still been 60 something.

My usual annual testing is 15kw for 1-2 min then 45min to an hour of 12kw.