Fuel Pump question for Zexel Kubota 1505 engine

[Zanshin]

The fuel pump on my Cummins-Onan MDKBM generator isn't working. This is a Bosch/Zexel 16060 pump on a Kubota 1505 engine. I have carefully removed it and disassembled it and even found the corrosion that might have stopped it working. But I have a problem, probably a big one. One that might cost me $1900 for a new injection pump.


The image shows the many parts already disassembled, and also shows 4 different shims marked 05, 12, 12, and 15. These are indeed very slightly different according to my micrometer. They are the part number 12 in the following image:

and are camshaft spacers. In the parts list there is no mention of different shim thicknesses, there's just one part number.

I carefully noted which shim went into which barrel when I took it apart, writing it onto a Post-It pad and stuck it to main pump body. But I couldn't crack the seals on the top part on board and don't have a vice; so I went ashore to a dock where I could whack away and get those bolts off. But while doing so, my Post-It flew away and into the water. I didn't notice that until too late...

I've reached out to Cummins-Onan, but doubt that they actually speak with mere customers and am not sanguine about my chances at getting an answer from them. I've search through the internet, but my Google-Foo isn't powerful enough to let me locate an answer.

But the Kubota 1505 is a popular engine amongst sailing folk, so I though I'd give it a try here!

[capt jgw]

Everything I've read about injection pumps says amateurs should never, ever try to repair one. Even my local Kubota dealer shop won't do it, they take the pumps off and send them to the local Diesel Injection Service shop. I had one that needed work and took it to the injection shop myself, they rebuilt it for $200. That was a two cylinder engine so $100 per cylinder, and about 10 years ago so no doubt higher now. So check if there's an injection shop near you and bring it in. That's a Bosch type pump, very common and used on a lot of different engines. They'll know how to fix it.

[Zanshin]

@capt_jgw - If there were a shop close to me, I wouldn't have touched the pump. I know that these are precision pieces of equipment. I asked if anyone would know which shims might go to which cam/cylinder and I gather from your post that you don't know that answer, either.

[skipperpete]

Ouch, that photo of the stripped injector pump is painful to look at. Plungers separated from the matched bushings, delivery valves and seats divorced and the whole lot in the one heap in a plastic container. What was wrong with the pump that you found it necessary to strip it down so completely.
In answer to the shim question, they are fitted by trial and error by running the pump on a dedicated machine that costs a helluva lot of money ( which is part of the reason pump techs charge so much). Each of those pump elements has to deliver a precise and calibrated amount of fuel equally to each injector (called calibration) at precisely the correct point of pump cam and engine rotation (called Phasing). It’s difficult to overstate the cleanliness and accuracy required to repair and adjust even simple pumps like the one in your photo. The good news is that your Kubota is a remarkably common engine in tractors, excavators,skid steers and even large pumpsets so there’s a chance that you might find a farm mechanic or even a diesel guy who can help you...... or you could take the other option that you mentioned, buy a complete new pump from Kubota or Cummins

[Zanshin]

@skipperpete - you are so right! I had all the components separated into 4 plastic trays prior to my Post-It fiasco and afterwards just threw everything together as I already suspected that I'd need to get a test-bench shop somewhere to recalibrate the pump. Since it was broken beforehand I figured it would be interesting to delve into some wonderfully precise engineering.
Only when I saw that simple cleaning would probably bring the pump back to life did I entertain hopes of saving some money... Alas, I've since learned that each pump will have different shims so even had I not made that mistake and put each piece back in the same position the odds of getting acceptable timing were pretty much the same as me winning the lottery
I'd already ordered an OEM pump from eBay for shipping to the Caribbean through a freight consolidator when I wrote the post, and it should arrive soon. The original Cummins-Onan pump is $1900 and the local technician who I wanted to work on the engine are dealers, so they would have had to buy the full-price one.

I still hope to put the pump back together after cleaning and make it work, then use that as a functioning return-core for a refurbished pump that I'll keep as a spare.

Thanks!

[Zanshin]

I cleaned all the parts and removed the corrosion that was preventing the pump from working. I've put it back together - that took a while as it really is a complex interaction between the parts. Of course I could only guess at which shim to put in which barrel. The pump is now working again - but I'm not going to install it, since the timings are guaranteed to be off. But now I can send this pump to get refurbished and re-calibrated. And it looks like shipping in the USA was faster than I'd thought and I'll get my new pump delivered to SXM on Tuesday.