Kubuta U50-5 Fuel Issues

There appears to have been a spate of fuel issues across the UK with Kubota U50-5 Excavators.

I thought it would be good to summarise what we have established with various conversations with our clients and Lister Wilder, Colchester Diesels and Kubota UK

• It only seems to affect the U50-5 models and no other models.
• This model has a D1803-CRTE5 engine c/w Bosch Injection System whereas most other Kubota engines in this size range are using a Delphi system.
• The failures are all of a similar ‘Fuel Contamination’ issue and would at first appear to be a fuel filter compatibility problem which is why we are very interested to find out where this is going wrong
• Issues we have found have had the following brands of filters fitted: Kubota Genuine, Blueprint, Donaldson, SF, Sure, Alco, HiFi and Holm
• The Bosch system apparently requires filtration to 4 micron.
• We have the spec sheets of the cross references and there is quite a variation between them:

• Kubota RD159-51022 superseded version of RD159-51020
• Kubota VO631-51880
• Sure SFF68233
• Donaldson P550049
• Blueprint  ADC42339
• Holm F10-0038-HOL
• SF Filter  SK3805
• HiFi  FT7220
• We have reports of several of this model machine with the same issues in varying regions across UK
• It doesn’t appear to be ‘Filter’ related as the same fault is happening regardless of what replacement filter is fitted
• Sites are reporting no other fuel related issues with other plant operating on the same site so it doesn’t appear to be a fuel contamination problem, coupled with the fact this isn’t an isolated incident or restricted to a specific area
• Colchester Diesels (Bosch Service agents) have reported that injectors are being damaged due to Fuel Contamination.

Logical summary:

• It doesn’t appear to be a fuel contamination issue due to the multiple incidents across regions and non-effect on other plant
• It doesn’t appear to be a fuel filter issue due to the fact we have had the same issue with all the above brands of filters fitted and we aren’t seeing a similar issue on other machinery
• It does appear to be something specific to the vehicle itself.
• What does the contaminated fuel contain?
• Could it be a critical component failure which is causing the contamination? IE Fuel Injector itself or Fuel Pump?   A true fuel test may help to prove this?
• In 2019 Ford Transit had a similar issue with a specific range of vehicles.

“Ford says the issue has been caused by quality problems with a third party supplier, which provides the injectors fitted in the Transit, Transit Custom and Ranger EcoBlue models.”

“Further to this, we understand that supplier is Continental, and that the failure is related to a surface coating inside the injectors. On some injectors this has been found to come unstuck, which soon leads to the injector becoming blocked and preventing it operating correctly.”  (Source Parkers)

• This appears to be Is this a Bosch issue?  (Kubota engines with Delphi are not having the problem)

If anyone has anything else to contribute to the dialogue it would be useful