1985 Evinrude V6 235 hp won't go to full throttle

[rejjr7]

Hi gang! Never posted before, just registered, in fact, first time I've ever owned a power boat! I am however, enjoying working on this massive outboard. When i bought it I rebuilt the carbs (there's three of them), replaced the impeller and all its associated parts, and replaced both thermostats.

Now when I take the boat out I can't get her on plane, can't get her past about 10 knots, and the engine won't throttle up much past maybe 1/4 throttle.

I'm sorry I haven't checked compression yet, I need to buy a tester, I'll do that very soon. But I did do two tests that I think may be telling.

1st - When the engine is idling and I spray a bit of carb cleaner in the top carb it bogs down for a second, same thing with the middle carb, however, spraying into the lowermost carburetor makes no difference in the running of the motor. Also, while the engine is idling I can take off the spark plug wire from the lower left plug or right plug and it makes no difference in the sound or cadence of the engine. If I take any of the other wires off it runs rougher.

I am no mechanic, so while this may seem obvious to most of you, I don't know what these symptoms mean, but I'd love to find out!

Any help would be very appreciated!!

Sincerely,
Ralph Jr.

 

[boobie]

Re: 1985 Evinrude V6 235 hp won't go to full throttle

Check the spark with an open air gap tester on those two bottom cyls. Sounds like you have an ignition prob. But check the compression first.

 

[markheb]

Re: 1985 Evinrude V6 235 hp won't go to full throttle

Don't run it anymore!!! Your bottom carb is not getting any gas through AND without gas going through, the #5 + #6 clyinders are not getting any OIL!!! When you did your carb rebuild did you replace the floats and needle valves? New floats and needle valves will need to be adjusted. ALSO, did you REALLY clean the carbs,, I mean take out the aluminum plugs, run wires, fishing line, etc. through all of the fuel orifices, carb cleaner and air pressure?
It's probably not a ignition problem as the bottom two cylinders run off of seperate power packs and coils, but check anyway with an open air gap tester ($7 at autozone). Compression check also - one that screws into the cylinder to get accurate readings - not the old ones that you just hold against the SP hole.

 

[emdsapmgr]

Re: 1985 Evinrude V6 235 hp won't go to full throttle

Looks like the two bottom cyls may not be firing. These engines will seem to run fine on only 4 of the 6 cyls when idling on the trailer. You've done some nice testing-the spark plug wire test is a good one. You can confirm that neither of the bottom plugs are firing by putting the lead of an inductive timing light on those two bottom cyls. Compare the gun flashes with the flashes from the top 4 cyls. The flashes from the gun will show misfires, nofires, weak firing. You could try to swap around some of the coils to see if the problem moves. Usually the coils are pretty reliable. If you are lucky, it just the coils. The power packs are identical, but it's unusual for a no spark problem on the same two cyls on different packs. Swapping them probably won't show any change. If you don't have a factory manual, you can check out the ignition troubleshooting tips at this website: cdielectronics.com. The packs are a common failure item, but you also have a timer base and stator in that system-all expensive items. Some further ignition troubleshooting will help make sure you replace the correct part(s) the first time. I'd check the output voltages from the stator and timer base-you'll need a special "peak reading" voltmeter.