It’s not about what goes wrong, it’s about how you react to what goes wrong

Scott’s Log – August 6th, 2025

Mario called me out and I have been pressed into service to write a short technical piece about what happened when Sarah Sarah’s John Deere SFM50 6068 (hopefully that’s technical enough) quit 7 miles from our destination. Mario shared how it played out, so I won’t cover that again. I think he just wants me to write the boring bits, so his articles look even better than they are. So be warned, this is the chronology of of the repair process and it’s a bit dry.

First a bit of background. The fuel system on Sarah-Sarah is generally pretty bullet proof. All fuel is polished (thoroughly filtered) on the way to a day tank and then filtered again before it goes to the engine where it is filtered two more times before it goes into a high-pressure fuel pump that feeds the cylinders for combustion. I say bullet proof because, generally, it is bad fuel that can cause diesel engines big problems and we are pretty certain we don’t get bad fuel to the engine. So, when the engine quit the first thing
we did was to check the errors codes which were brought to our attention by a very loud, won’t-let-you-think-straight alarm. We got two primary error codes that indicated we had a high-pressure fuel problem and one error code that essentially told us the engine would derate itself for protection.

The other thing to remember is that the Engine Control Unit, made famous in an early post, essentially controls everything the engine does and is responsible for sending the error codes and the annoying alarm to the dash. Looking up the error codes meaning, which Bill did straight away, would have led me to
immediately replacing the high-pressure fuel pump. However, my approach to problem solving on the boat is to slow down and take a full inventory of all my resources. I like to think through the problem and discuss it with the crew as you never know what people know until you ask.

First, I asked my son Bill to find the best video he could for changing the fuel pump on a 6068 Deere. Then, I reached out to a John Deere dealer on the west coast because it was late on the east coast. I later reached out to a dealer on the East Coast because I wanted to tackle the problem first thing in the morning. I also pulled out my spare pump and brought up the repair manual so I could read all about the process. The video was pretty bad, but I was reminded of one important thing before I even cracked the repair manual. The position of the engine relative to the position of the high- pressure fuel pump is important. If you miss-align the mechanical gear during installation, the pump will push fuel to a cylinder that has a closed intake valve. The engine will not run. After the video and spending time with the repair manual, I wrote down a full step-by-step procedure and sent it for review by the professionals.

Since the ECU controls everything it was worth testing the ECU. First, we removed the cable from the ECU and used dialectic grease and reseated the plug in the event we had a poor connection, no change. Then we tried the newly acquired spare ECU, no change. Then we unplugged the high-pressure pump cable and plugged it into the new pump, no change. Guessing that all of the easy things were tried and eliminated, we
readied the engine for the replacement fuel pump. This isn’t simple unless you have the right tools. You have to have a JDE81-4 to rotate the engine and a JDE81-4 timing pin to find Top Dead Center (TDC) for the engine. With those, you have a 50% chance of being right. You also need a KJD 10233 to lock the fuel injection pump to ensure you are at TDC for the number 1 versus the number 6 cylinder. We did not have the Fuel Pump Pin, but we could use a screwdriver and essentially get to where we needed to be. For the more mechanically inclined, yes, we could have taken off the valve cover to confirm the intake valve was opening but that would just add more work.

We had already removed the two engine fuel filters when we got back on a call with Jerry, the expert at James River. His experience suggested the problem might have been caused by the low-pressure pump that was installed between the two engine fuel filters. We, of course, had one in our spares inventory so out it came. After some tense moments with a brass compression sleave that we had to carefully remove from the old pump and install on the new pump, we had the fuel system closed up again. Back on the phone with Jerry, because we were still not getting any connection from the ECU to the panel on the dash. The message displayed was “No Parameters Found” and all the gauges were dead. Essentially, the ECU should send this information to the dash when the key was turned on. That wasn’t happening. So, we had to chase the wire harness connecting the ECU to the dash. We found and reseated the plug with dialectic grease and still no information exchange. So, who the heck carries a spare engine gauge cluster…that was a step to far even for me. However, Sarah-Sarah has a Maretron system that gets its information from the ECU. Yep, a backup to the gauge cluster!

We fired up the Maretron and were encouraged that we had an engine coolant output from the ECU. We then turned the key at the dash and you could clearly hear and feel the low-pressure fuel pump working to get fuel to the system. That only happens if the ECU is working so we were encouraged. Jerry then had me prepare to jump the starter motor. I didn’t love the idea because it involves high amperage electric current and I hate electricity. Thankfully, I asked if we could just push the start button without harm and of course we could. So we did and the engine fired up. We get could information to the Matron so having a dead gauge cluster wasn’t the end of the world. We ran it for ½ an hour and then set out the next day without incident.

So what have I learned from all of this? First, I need to take stock of the spares that I have and read through manual to understand what special tools might be necessary to replace each part. Having the part without the ability to use it would be very frustrating indeed.

Second, I need to continue to chase the little things like connections and fittings. Had we not had success removing the brass compression fitting we would have been challenged to connect the new low-pressure fuel pump to the system. Bottom line, if you want to be mostly self-sufficient and be prepared to repair the systems on your boat, you need to be systematic and carefully go through each system and ask the experts. As much as I know about this boat and its systems, I didn’t learn it all at once and I didn’t learn it on my own. I have developed a network of go-to people that I rely on for help.