Universal M-12 High Pressure Fuel Pump

[Afrakes]

I picked up a good candidate engine to rebuild. It's a thing I do with my grandsons. Unfortunately, the high pressure fuel pump is shot. Anybody out there have a line on one. I don't believe that they're manufactured anymore. At least I don't seem to be able to find one.

 

[Dave G.]

I presume you are talking about the injector pump? According to uncle google the M12 is a Z400 series model Kubota engine. Hopefully you can find a Kubota part # on the pump to be absolutely sure of the replacement. There seems to be options for Kubota pumps and rebuild kits, some pretty pricey though...Good Luck !

 

[Kenneth K]

My neighbor had his injector pump rebuilt twice by a local shop. There are still marine/diesel ships that do this kind of work.

 

[Afrakes]

Thanks for the responses. It is the injector pump. The Kubota tractor reference is G3200 and the part is no longer listed on the Kubota site. All references I can find say that the part is not serviceable. I'm going to strip this one down and take a look.

 

[Pete the Cat]

Thanks for the responses. It is the injector pump. The Kubota tractor reference is G3200 and the part is no longer listed on the Kubota site. All references I can find say that the part is not serviceable. I'm going to strip this one down and take a look.

Are you familiar with injector pumps innards? I have never had the guts to mess with one. Most of the mechanics I know take them to a diesel shop that specializes in rebuilding them--I have always been told that you do not want to open one unless you are experienced. My understanding is that most all of them can be rebuilt. I have had a couple rebuilt at a local shop. I think this often can be done with generic replacement parts.

 

[Dave G.]

Here is a cross reference for Universal to Kubota. Be advised that Kabota sells parts by the tractor/mower model and not by engine model/type.

https://ericsonyachts.org/ie/attachments/universal_diesel_-20engine_data-pdf.5531/

 

[Afrakes]

Are you familiar with injector pumps innards? I have never had the guts to mess with one. Most of the mechanics I know take them to a diesel shop that specializes in rebuilding them--I have always been told that you do not want to open one unless you are experienced. My understanding is that most all of them can be rebuilt. I have had a couple rebuilt at a local shop. I think this often can be done with generic replacement parts.

I have an extra one from an engine that drowned in salt water. Very rusty. I have it soaking in Kroil in hopes of loosening it up for disassembly. I'll search for a local service shop that will touch the pump. Not many choices in this area.

 

[Loren Beach]

In our city there are one of two small companies that do this work as well as rebuild injectors. And their work is probably 99.8% oriented to the trucking industry. A mechanic I know said that those guys will have a basic "clean room" for work on the high pressure pump and that there only a few makes of pump for most engines including Kubota's.
On our former M25XP, we only ever had to have new tips on the injectors after taking them in to have the spray pattern checked, so I was spared learning more about the high pressure pump...
I have been told that the pumps are relatively expensive.

 

[Afrakes]

In our city there are one of two small companies that do this work as well as rebuild injectors. And their work is probably 99.8% oriented to the trucking industry. A mechanic I know said that those guys will have a basic "clean room" for work on the high pressure pump and that there only a few makes of pump for most engines including Kubota's.
On our former M25XP, we only ever had to have new tips on the injectors after taking them in to have the spray pattern checked, so I was spared learning more about the high pressure pump...
I have been told that the pumps are relatively expensive.

The last cost figures I have are from 2018 and the pumps were over a grand. There's a local performance diesel outfit I'll give them a try.

 

[Pete the Cat]

I have an extra one from an engine that drowned in salt water. Very rusty. I have it soaking in Kroil in hopes of loosening it up for disassembly. I'll search for a local service shop that will touch the pump. Not many choices in this area.

I have seen on line diesel service businesses who will do the work if you mail the unit to them. You would need to assure they are prepared to service your model.

 

[Loren Beach]

Need help servicing Universal 5411 high pressure pump - Cruisers & Sailing Forums

Hi all - working on a friends boat . No start situation - valves all opening and closing, tested for fuel at high pressure pump port and it was coming thru- cracked injector lines with decompression

www.cruisersforum.com

Reply #4 seems relevant.

 

[Afrakes]

The fuel delivery system on the 5411 and M-12 are different. No need to bleed the M-12 as the diesel is constantly flowing through the injector pump and injectors once the electric fuel pump is operating. I double checked and fuel was entering the injector pump. While the engine was cranking, I cracked the lines to the injectors and got nothing. I tore down the spare rusty injector pump. More on that later.

 

[Afrakes]

This is what an M-12 injector pump looks like broken down. All of the items on the left side of the photo comprise one of the two active "elements" of the pump. No rocket science except for the engineering part. Easy to disassemble once you take a good look at it. Certain parts are keyed for orientation. I removed the injector pump from my candidate engine. It seems that one of the two springs within in one of the "elements" has failed causing it not to make contact with the fuel drive cam shaft and leaving it in position to prohibit fuel flow. Both elements need to function together. Now I have to decide if I'm brave or foolhardy enough to attempt a repair myself.

 

[Pete the Cat]

This is what an M-12 injector pump looks like broken down. All of the items on the left side of the photo comprise one of the two active "elements" of the pump. No rocket science except for the engineering part. Easy to disassemble once you take a good look at it. Certain parts are keyed for orientation. I removed the injector pump from my candidate engine. It seems that one of the two springs within in one of the "elements" has failed causing it not to make contact with the fuel drive cam shaft and leaving it in position to prohibit fuel flow. Both elements need to function together. Now I have to decide if I'm brave or foolhardy enough to attempt a repair myself.

As I mentioned, I have never opened one even when rebuilding the couple engines I have done, I just sent them out. I am told that those O rings are very precise and that my Harbor Freight collection will not work "just as well". I also think there are probably torque specs and such as these injector pumps work at very high PSI. Keep us in the loop if you decide to do it. I think there is a Youtube video I saw on an small diesel overhaul where the guy took the injection pump apart. I recall that it confirmed my commitment not to mess with them--but that might have been an emotional reaction.

 

[Afrakes]

So, after getting a full parts breakdown (numbers only, no descriptions) from a friend of mine, I went at it. Came apart easily. Was careful with the Orings. This engine came out of an 86 E-28/2 which was abandoned at the marina I use. I hope that the owner didn't abandon it because the engine didn't work. The solution was a good cleaning of the internal parts of the pump. One of the two internal elements worked fine so left that one alone. I disassembled the other and found that two of the parts that produce the high pressure were frozen. Removed them (basically a tube with a piston) and let them soak in acetone overnight. Still couldn't get them apart. Tried a bit of heat and that didn't work. The top of the tube had a small opening giving access to the top of the piston. I ground down a brass threaded rod so it would fit in the opening and gently drove the piston out. Both parts were pretty gummed up and it took quite a while of soaking and working the parts to get everything cleaned up and moving freely again. I have reassembled the pump. I'll put everything back together tomorrow and hopefully the engine will run.

 

[Christian Williams]

Enjoying this heroic intervention and hoping it works. But it's beyond me.

I'd probably explore equivalent of this guy, on eBay, who says send the pump to him. He doesn't give a cost, but probably would on the phone.

Kubota Fuel Injection Pump Service REBUILD SERVICE | eBay

I will communicate this information to you and keep you updated. Upon receipt of your pump I will disassemble and replace the worn internals of your pump (springs, spring seats,o-rings, copper washers).

www.ebay.com

 

[Afrakes]

Success. This engine has not run in at least ten years. It took a bit of fiddling around, but it did start and run. I have a video on my iPhone 11 that I can't seem to download to this site. I'll keep trying.

 

[Christian Williams]

Great.

I don't think the site can host video. You have to upload the file to YouTube or Vimeo or similar, then provide the link here.

 

[Afrakes]

If you want to hear it run. Go to YouTube videos, M-12 Reborn. No narration.

 

[G Kiba]

Good job. Motor sound great Al.