Need Injection Pump For MEP-003

[The Doktor]

Hi, I'm hoping somebody on this board can help me. I have an older friend who has basically a civilian version of the MEP-003, it is 10kw powered by the four cylinder Onan diesel. He starts this generator approximately once a month to make sure he's in good running condition, the last time he tried to start it would not start. uUpon further inspection, he found the injection pump was not delivering fuel, and eventually found out the reason it was not pumping was because the plunger is broken. This is an older unit, and it has the PSU pump.

I am hoping somebody can direct me to a used pump at a decent price. I believe this can use either the PSU or be fitted with the newer AMBAC M50 ( please inform if modifications are necessary), but I don't know what advantage one has over the other.

Is a broken plunger a common occurrence on these pumps? Any less of a problem on the AMBAC M50 ? I ask because I can't see any reason for this plunger to have broken. I would expect such a failure if he plunger where to become rusted in its bore, but that is not the case here. The inside of the pump is clean with no rust or corrosion noticeable anywhere, and the plunger is free to move in the hydraulic head. It does have a little resistance, but not to the point where you need pliers to move it or anything. Also, there is no scoring or gouging on the sides of the plunger, it looks to be in good condition. It failed seemingly without provocation, the generator ran good one day, the next time an attempt was made to start it, it simply didn't work.


Thanks
Ed

 

[Light in the Dark]

There is no parts support on the PSU. The Ambac can be rebuilt, but I have no experience with it. Many here in the forum do though.

They can also be purchased outright from time to time through eBay, but if you have the skill... DIY rebuild is the much cheaper method.

 

[Mullaney]

Hi, I'm hoping somebody on this board can help me. I have an older friend who has basically a civilian version of the MEP-003, it is 10kw powered by the four cylinder Onan diesel. He starts this generator approximately once a month to make sure he's in good running condition, the last time he tried to start it would not start. uUpon further inspection, he found the injection pump was not delivering fuel, and eventually found out the reason it was not pumping was because the plunger is broken. This is an older unit, and it has the PSU pump.

I am hoping somebody can direct me to a used pump at a decent price. I believe this can use either the PSU or be fitted with the newer AMBAC M50 ( please inform if modifications are necessary), but I don't know what advantage one has over the other.

Is a broken plunger a common occurrence on these pumps? Any less of a problem on the AMBAC M50 ? I ask because I can't see any reason for this plunger to have broken. I would expect such a failure if he plunger where to become rusted in its bore, but that is not the case here. The inside of the pump is clean with no rust or corrosion noticeable anywhere, and the plunger is free to move in the hydraulic head. It does have a little resistance, but not to the point where you need pliers to move it or anything. Also, there is no scoring or gouging on the sides of the plunger, it looks to be in good condition. It failed seemingly without provocation, the generator ran good one day, the next time an attempt was made to start it, it simply didn't work.


Thanks
Ed

.
Hi Ed,

A quick Welcome to the outfit!

Don't know if any of our other guys happen to know of a cache of parts.

 

[cuad4u]

Delk's in Asheboro, NC have (had) rebuilt IP's. I bought two. I used one and I put the other on the shelf as a spare. If you find one, your MUST mate your buttons to the new IP.

 

[Guyfang]

Better yet, PM RAY70. He can give you more info on this then the entire internet.

 

[Ray70]

Yup, Guy is most likely correct. I know because I have a pile of PSU parts ( everything except good plungers ) from all the broken pumps I have run into.
As a result of the catastrophic plunger breakage, Ambac redesigned the pump to use the Plunger guide as the sacrificial "Shear Pin", thus making the M50 repairable in 99% of the cases. I have only once gotten an M50 that could not be rebuilt due to slight pitting on the plunger's tip rendering the plunger useless.
The reason the PSU plunger and M50 plunger guide break is that the crappy fuel of today quickly turns to gummy varnish and can stick the plunger to the pump head. as soon as you turn the engine with the plunger sticking, the plunger guide or in the case of the PSU, the plunger itself, right where the drive pin hole is, will break due to the inability to turn the plunger.
Remember, the tolerances between the plunger and pump head are so tight that just the heat from your hand can cause a new plunger to grow enough in size to not fit into the cooler pump head until the temp equalizes. So it doesn't take much to cause the plunger to get stuck.
many of the internal parts are different between the PSU and M50, Plunger, gear, plunger guide etc.
Your best bet is to find a used, rebuilt or core M50 pump and ditch that unserviceable PSU.
Only issue is that pumps are becoming like the proverbial "Hen's teeth"!
Occasionally a good used pump comes up in the $450 -$600 range and rebuilt ones occasionally are on ebay for $750 ( think there may still be one )
Then there are some space cadets out there asking $1200 to $1600 or more! You can buy a new engine cheaper!
If you end up finding a rebuildable core I can either talk you through rebuilding it or I can rebuild it for you.
Only thing you need to do is read up on how to set the engine at the "PC" mark to remove / install the pump.
The shim that is between the block and pump stays with the block.
You should perform the flow timing test shown in the TM and the Ambac service guide because a different pump may very likely need a different timing button than the original pump did, but the original button is a good place to start from.
If you have any questions either ask here or PM me.
If you need the Ambac installation , parts or service manuals I have them and I think they are posted here in the TM section as well under the 002/003

 

[The Doktor]

Thank you all for your help. Got a rebuilt pump at Delk's, $650 including $50 core charge since the old pump was not rebuildable. I explained how the spill timing works, I think the guy understands it pretty well.

Although I'm capable of repairing the pump if the guide breaks, I would like to avoid it. I'm also not sure which pump his other, military version, is equipped with. Is there any fuel additive that will prevent this problem?


Thanks
Ed

 

[Guyfang]

Simply running the set for a few hours a month would go a long ways toward that direction. I am sure there are some additives that would do the trick also. But simply running it works well.

 

[Chainbreaker]

...Although I'm capable of repairing the pump if the guide breaks, I would like to avoid it. I'm also not sure which pump his other, military version, is equipped with. Is there any fuel additive that will prevent this problem?

Thanks
Ed

Care of the entire fuel system starts with the diesel you buy. Biodiesel, Air and Water are the enemies of maintaining good diesel quality. I do not buy the more discounted, around here, B20 Biodiesel for my generators. I only buy the standard minimum B5 Biodiesel offered at non-discount pumps in my area. Some people buy off-road diesel which I believe is B5 as well, it just doesn't include the road tax and is cheaper if you can buy in bulk.

The next requirement is maintaining the filters, in the Military version MEP-003a/-002a its starts all the way from the screens in the bottom of the Facet Fuel pumps to the OEM fuel filters (or spin-on filters) as may be the case. If there are water drains in filters use them before every start up to drain off any condensation that may collect in fuel due to tank vent breathing or any water transferred via refueling. Also, I have found that fuel tanks seem to get yucky inside with gummy slime in 4 years or less depending on climate and should be removed and thoroughly cleaned (power wash/chemicals etc.) once they reach that condition. The yucky tank condition becomes a problem especially in high humidity areas coupled with day/night temperature changes encouraging tank breathing and absorbing water laden air in stored fuel.

Next on the agenda, is proactive fuel maintenance via fuel treatment. There are all kinds of thoughts on fuel treatment...as a minimum I use a biocide treatment and diesel fuel additive that ups Cetane, adds lubricity and helps clean injectors. My personal fuel treatment preference is Biobore JF coupled with Optilube XPD. Other comparable brands should also work.

If you believe there is any built up varnish in fuel system then I would start off with more of a fuel system cleaner like Seafoam or equivalent. You can even fill a fuel filter cannister with Seafoam (Mfg indicates its safe to run a can full strength) to help clean IP, Injectors, cylinders, etc. I know of at least one SS member who routinely does the last fuel cannister full of Seafoam treatment on MEP-002a/-003a's as needed and has obtained very good results.

Then make sure when you run it you can put a good load on it to work it. I use a Comfort Zone garage heater as my load bank when exercising my gensets Quarterly. In between my full blown quarterly runs I try to run them for 15 minutes monthly just to keep the fuel circulating and heating up the genset.

 

[Mullaney]

Care of the entire fuel system starts with the diesel you buy. Biodiesel, Air and Water are the enemies of maintaining good diesel quality. I do not buy the more discounted, around here, B20 Biodiesel for my generators. I only buy the standard minimum B5 Biodiesel offered at non-discount pumps in my area. Some people buy off-road diesel which I believe is B5 as well, it just doesn't include the road tax and is cheaper if you can buy in bulk.

The next requirement is maintaining the filters, in the Military version MEP-003a/-002a its starts all the way from the screens in the bottom of the Facet Fuel pumps to the OEM fuel filters (or spin-on filters) as may be the case. If there are water drains in filters use them before every start up to drain off any condensation that may collect in fuel due to tank vent breathing or any water transferred via refueling. Also, I have found that fuel tanks seem to get yucky inside with gummy slime in 4 years or less depending on climate and should be removed and thoroughly cleaned (power wash/chemicals etc.) once they reach that condition. The yucky tank condition becomes a problem especially in high humidity areas coupled with day/night temperature changes encouraging tank breathing and absorbing water laden air in stored fuel.

Next on the agenda, is proactive fuel maintenance via fuel treatment. There are all kinds of thoughts on fuel treatment...as a minimum I use a biocide treatment and diesel fuel additive that ups Cetane, adds lubricity and helps clean injectors. My personal fuel treatment preference is Biobore JF coupled with Optilube XPD. Other comparable brands should also work.

If you believe there is any built up varnish in fuel system then I would start off with more of a fuel system cleaner like Seafoam or equivalent. You can even fill a fuel filter cannister with Seafoam (Mfg indicates its safe to run a can full strength) to help clean IP, Injectors, cylinders, etc. I know of at least one SS member who routinely does the last fuel cannister full of Seafoam treatment on MEP-002a/-003a's as needed and has obtained very good results.

Then make sure when you run it you can put a good load on it to work it. I use a Comfort Zone garage heater as my load bank when exercising my gensets Quarterly. In between my full blown quarterly runs I try to run them for 15 minutes monthly just to keep the fuel circulating and heating up the genset.

.
Not sure that there is an official amount of time on your monthly run. Just curious to know if everything really gets warm enough? The guys in the building behind ours has a CAT generator that they run for an hour. Their's must be on some sort of timer because at 0900, she fires off and runs up to speed. At exactly 1000, it powers back down. I can set my watch by it... If it matters.

 

[steelypip]

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Not sure that there is an official amount of time on your monthly run. Just curious to know if everything really gets warm enough?

The good news is that the MEP-002A and -003A are air cooled engines, so there's no water jacket to warm up. They get up to temperature pretty quickly under full load. Start it, let it calm down a minute or so, then put full load on it. I usually run mine at full load about another five minutes after I've noticed that the cooling air shutters are open the 'normal amount' for my generator at full power. Then I take the load off, let it run another five minutes after that to cool down the heads and jugs, then shut it down.

So it might be as few as 20 minutes, but however long it is, I got it properly hot first.

 

[Chainbreaker]

.
Not sure that there is an official amount of time on your monthly run. Just curious to know if everything really gets warm enough? The guys in the building behind ours has a CAT generator that they run for an hour. Their's must be on some sort of timer because at 0900, she fires off and runs up to speed. At exactly 1000, it powers back down. I can set my watch by it... If it matters.

With my "quarterly load test" runs I first let my MEP-002a gensets run a few minutes to bring up to operating temp and then exercise genset using my 240V Comfort Zone garage heater in increments of 3000w, 4000w then 5000w and after a few minutes work it back down and then let it idle down to cool down a bit and then shut off. Takes ~30 minutes unless its colder/rainy outside and I decide to run longer. I always run long enough for the cylinder shroud louvers to open being an air/oil cooled engine.

For my non-quarterly in between "monthly function test runs" I run the gensets mainly to get fuel flowing through the system (don't want stagnant fuel sitting in IP or injectors too long) and to heat up enough to drive off any moisture and hopefully drive off any critters thinking about making a home. That usually takes ~10-15 minutes depending on out outside ambient temperature. Keep in mind that I have battery maintainers on all my units so having to account for adequate battery charging time is not a factor. Also, my trailered gensets are PU-751M's and thus are enclosed with OEM trailer covers plus one genset that I transplanted into a NF2 light tower enclosure. Being up off ground on trailers & enclosed helps with them being protected from the elements plus any residual heat is captured to further dry up moisture (especially during the rainy winters in Oregon) when I close them up and batten down the hatches.

Certainly with other genset scenarios...water cooled engines, especially if not protected very well from the elements or larger kW genset with larger radiators would require longer duration monthly test routines especially as necessary to prevent or burn off wet stacking.

Anyway, my routine seems to be working well for my air/oil cooled 5 kW gensets over the past 7 years. Fingers crossed they soldier on for another 7+ yrs.

This is probably a bit off the OP's injector pump repair issue... however preventative maintenance and exercise are key to preventing future IP issues.

 

[Guyfang]

PPPPPPP.
Propper Prior Planning Prevents Piss Poor Performance.

 

[Mullaney]

PPPPPPP.
Propper Prior Planning Prevents Piss Poor Performance.

.
Our version was one less "P".
Just six and I think we figured any planning was going to be more proper than doing nothing.


Thiose words were definitely shuffled around too.