I would like to share with other Nonsuch owners an engine issue which I experienced sailing home from Maine. The trip was largely motor-sailing over four days. The first two days the engine ran flawlessly. On the third day, after about four hours, the rpm’s slowed down from 2500 to 2200. It sounded not as smooth, perhaps running on 3 of the 4 cylinders. The rpms went up and down thru the 2500 to 2200 range very slowly for approximately 20 minutes. The engine ran normally after 20 minutes for another hour or so. Then it repeated the rpm changes for another 20 minutes. It ran normally for two or three hours to our destination and again the next day the engine ran normally for the last three hour run.
The bowl on the Racor fuel filter was perfectly clean, no water showing, the engine water temp was perfectly normal, no obstruction to the air intake filter. There is a breather hose coming from:the valve cover gasket, which I have routed (several years ago) close to the engine air intake filter. Engine oil level near top. The injectors were cleaned and recalibrated 12 years ago.
Recently, I’ve cleaned my diesel tank to solve an engine problem that started like yours. My first thought was also the lift pump. Further investigation learned that the pump worked fine but could not suck diesel out of the tank because of a blocked suction tube. The plastic tube was just 3 mm above the bottom of the tank and was easily blocked. I cut off an extra few millimeters of the tube to prevent future problems.
There was no access to the aluminum tank, so I installed two Vetus Inspection lids, type ILT120B. (Be sure to get the Vetus saw tool as well) The installation is easy and straight forward. With the lids in place, you can clean the tank. It’s a dirty job, but it solved my problem.
Rick, it sounds very much like problems I’ve had in the past. It appears that your engine is starving for fuel. I suggest that you check your filters starting with the filter in your Racor. In my case that filter was clogged and the engine showed similar symptoms and eventually stopped completely. I changed the Racor filter and the problem was solved.
One other instance was when the through hull for the fuel tank breather hose was blocked by a huge spider and nest of spider eggs. This actually caused the plastic bowl of the factory issued Racor to collapse.
Hope this helps…Ron
Ron & Diane Schryver
“Alpha Waves” 1987 NS30U #393
Georgian Bay Midland ON
I also agree with the others, sounds like a lack of fuel problem, hopefully caused by clogged filters. My tank had a lot of sludge in it from years of growth and I emptied it and cleaned it out completely. I now also change all 3 of my fuel filters every season for about $30, which is worth the peace of mind.
Bob Gehrman
NSU #396 “Quickbeam”
Baltimore, Maryland
I would check all your fuel filters but I suspect Mark H is right. There is a small screen at the bottom of the fuel pick up tube that has been blocked on a number of our boats. Same symptoms that you experienced. If not addressed it will likely get worse until the engine won’t run.
Many years ago, before the internet when boaters had to rely on magazine articles, this subject came up about that strainer at the bottom of the pickup tube and shortening the tube itself. i don’t think that those strainers come on boats anymore.
Joe Valinoti
S/V iL Gatto NS30U #221
Sea Harbour YC
Oriental, NC USA