Perkins 4-107 surges

[msrcal36]

Running at 1500 RPM the engine will surge 500 to 1000 RPM after 10 - 15 min run time. The the frequency increses to 1 - 2 minutes and the surge increases to 1000- 2000 RPM. Boat speed increases when this occurs. The RPM rackets up and will not throttle down. It remains at the higher RPM when shifted to neutral. I then shut engine down and after 5 minutes restart to normal idle RPM, about 500. Then the surge build up begins again. Any ideas appreciated.
Thanks Mike Robinson. mikesrobinson@hotmail.com

[RobTryon]

Hi Mike, Two things I thought of. 1. Fouled fuel filters, pressure builds up making engine surge. 2. High pressure pump is failing, time to rebuild it and have the injectors done at the same time. Good to see you guys the other day.

Rob

[Diesel Bill]

Try bleeding the injection pump and injector lines. Any air getting into the system will cause erratic RPM's.

[boatnerd]

If your brave and good with a wrench remove hp pump. There's a good chance it's gummed up inside governor assembly. Diamond Diesel in Oakland can service it but won't be cheap. Or you can get $50 seal kit and service it yourself. Watch YouTube video "Fergusion FE35 injector pump reseal" by Bundy Bear Shed. Same CAV pump as 4107. Look for CAV manual online too. Isn't that difficult. These HP pumps can be serviced in the field by a competent mechanic.

[Triumphant]

It could also be a fuel pump starting to fail