View Full Version : 3GM30F Fuel Usage

08-20-2008, 06:33 PM
"Our 1987 Schock 34PC fuel per hour rate has gone from approx. 1/2 gallon per hour to 1 1/2 gallons per hour. The engine starts easily (some grey smoke at first but stops) and runs very well.

We are not the original owners and have no idea of the engine hours, but when surveyed it was estimated that the boat had "low" hours (500 or so).

There is a light film of black soot on the stern very (uncommon for our boat) which I would attribute to the excess fuel usage. When not sailing and using the motor we cruise at 2700 RPM with occasional runs to 3000, the temperature stays at approx 180 F.

Any help to help (a list of things to check would be appreciated)to resolve this excessive fuel usage would be very much appreciated.


08-20-2008, 08:15 PM
Sounds as if an injector is hanging up (weeping)Remove them and have them checked. Get the correct injector packings and replace them. Your engine should be run at 3000 rpm cruising. That gives you max torque and min fuel consumption. Good luck.. Ron

08-20-2008, 08:24 PM
Thank you very much for your suggestion. I will get the injectors checked ASAP. We live north of Seattle would you know of a business in the area that could check the injectors?"