91 70HP Johnson running 3800 RPM@WOT

[ggrimm01]

Today I took the boat out and could only get 3800 RPM@wot. However when I started to prime the engine the RPM starting coming up to normal. I was priming from the key. Last year the outboard had the VRO disconnected and the oil was being mixed with the gas. Engine runs fine with VRO disconnected. Over the winter I went through the motor and put a brand new VRO pump. fuel line and went to the factory OEM Evinrude plastic gas tanks. Compression is good and within 5lbs of each cylinder. Yesterday I had the water hooked up to the intakes and its shoot out a nice stream and idles great. I put throttle on the engine and climbs great. By hooking the VRO back up is there anything I need to check to make sure the timing is correct?

 

[racerone]

VRO has nothing to do with spark timing.

 

[flyingscott]

Why do you think the timing is off sounds more like a cylinder not working

 

[ggrimm01]

The cylinders were reading 119, 115, 117, with compression test. Last year I removed the 3 spark plugs checking each plug for spark. All had good spark. I have not checked this year. However I did notice by touching the spark plug cables on the middle cylinder, I was getting shocked. I will redo the spark test and check the fuel connections tomorrow.

 

[flyingscott]

Also make sure the carbs are opening all the way and unless something catastrophic happend or the timing was adjusted it doesn't just go out.

 

[ondarvr]

If using the primer helped, then you have a fuel delivery problem, with the VRO pump being new, I would suspect some crud in a carb.

 

[ggrimm01]

Today I check the spark and all had a nice strong spark.. Nice and strong spark. I mixed 1 can of seafoam and 1 gallon of gas together and ran the engine for about 15 min to clean out the carbs. I checked the throttles @WOT and all were opening. One thing I did notice is spraying the carb cleaner on the bottom 2 carbs and the engine would bog down and spit and sputter.

 

[racerone]

If the spray on the bottom 2 carburetors makes it sputter it means that those 2 are working fine.-------Look into issues with the top carburetor !--------And you must find the issue.------Blockage in the top carburetor means no fuel going in and thus no oil !

 

[Tim Frank]

Today I check the spark and all had a nice strong spark.. Nice and strong spark. I mixed 1 can of seafoam and 1 gallon of gas together and ran the engine for about 15 min to clean out the carbs. I checked the throttles @WOT and all were opening. One thing I did notice is spraying the carb cleaner on the bottom 2 carbs and the engine would bog down and spit and sputter.

Sounds like you need to actually R&R the top carb. Using the "magic spray" is a shortcut that works occasionally (never for me ) ....but is no substitute for doing it properly.

Not sure what "nice strong spark" means. It sounds from post #4 that you just did the "lean a plug against the block" test which does not really tell much. The proper way is with a spark tester so that you can verify he size of gap that the spark will jump....in this case at least 5/16". ( that's about 10 x the normal gap)

 

[ondarvr]

Like already mentioned, fix it before you do severe damage to the motor.