EVINRUDE 91 70HP LOSES RPM

[PETER LYLE]

rpm are fine at all speeds on flat water when i hit asmall wave the rpm drops by1500 approx then picks up in few secs.dlr has replacedor switched powerpack,wiring harness carbs, fuel tank, hoses oil injection,plugs,wires and after 6 mos and no tech help from bombadier has given up.any ideas?

 

[seahorse5]

Re: EVINRUDE 91 70HP LOSES RPM

Has anyone put a timing lite on one wire at a time to see if it is ignition related? One can also watch the carburetor high speed nozzle flow to see if it decreases. An educated guess is a loose connection or an internal break in a wire.<br /><br />What do you mean Bombardier gives up?

 

[PETER LYLE]

Re: EVINRUDE 91 70HP LOSES RPM

thanks for the response.bombardier would not respond to the dealers request for assistance.all wires have been replaced and dlr checked the fuel flow.i am wondering if it might not be related to the overheat goernor or over rev cut off maybe abad connection as it only happens when it hits asmall wake or wave.the dlr had it for 6 mos and switched just about every possible thing with agood motor to no avail.

 

[clanton]

Re: EVINRUDE 91 70HP LOSES RPM

What is full throttle rpms? What is cylinder compression? If dealer is doing trouble shooting by changing parts, look for different dealer.You should be able to connect a peak read meter to the ignition system run in water full throttle and verify the ignition is ok.

 

[PETER LYLE]

Re: EVINRUDE 91 70HP LOSES RPM

dlr did all that and every thing checked out ok. theytested compression at 140psi allcylinders test drove at night and noticed arcing oncoils and plug wires then replaced them isolated boatwiring and control box ran with red plug disconnected. they replaced timer base tested vro pump failed test and replaced pump installed agood used wiring harness replaced flywheel swapped carbsand intake with reeds from a good running motor.they changed spark plugs thermostat replaced statorreplaced timer base. used timing light which shos engine has spark on all cyls even when problem occurs.the problem is so consistent that dlr can predict the precise moment the motor wii lose power.problem could not beduplicated at dock with a test wheel.I have had a good longterm relationship with this dealer and problem has them so frustrated they would not give me a bill for any of the work and left all parts on the motor.The boat goes like arocket untill i hit awave and would be ashame to junk it without requesting all your expert knowledge.Thank you for your responses.