2000 J70PLSSD no spark #3 cylinder

[scottro]

Joe can a VRO problem/alarm cause lack of power? If not I think it is either a weak timing magnet or power pack. I replaced the flywheel last year due to the magnet being loose. Just going by the timing light flashing the three cylinders seem to have the same consistant spark.

[Joe Reeves]

Joe can a VRO problem/alarm cause lack of power? If not I think it is either a weak timing magnet or power pack. I replaced the flywheel last year due to the magnet being loose. Just going by the timing light flashing the three cylinders seem to have the same consistent spark.

The VRO is counted on to supply the carburetors with the proper fuel mixture and quantity so any failure within it is going to affect the running of the engine... BUT... unless the failure includes fuel leaking down that pressure hose into just one cylinder's area, the failure would affect all the carburetors.

[scottro]

Faulty ignition on #3 seems to be the problem as when you switched carbs 1/3, the problem stayed with #3 cylinder.

However, your mention of a fuel soaked cylinder has me wondering.... I assume your engine has a VRO. Is it #3 crankcase area that powering that fuel pump? If so, remove the pressure/vacuum hose from the pump temporarily, then pump up that fuel primer bulb to see if perhaps a diaphragm is letting the fuel mixture into that hose. If so, it would be like running the engine with the choke butterfly closed on one carburetor. Far fetched maybe, but.......... Just a thought.

Joe I pulled #3 carb and I went in to check the reed valves in #3 incase one was broken. They looked fine and I decided to crank the engine to see them operate properly. Guess what I found, fuel pouring from the notch below the far right reed.

And I mean pouring out the hole. So despite the primer bulb test being negative it still seems like you were correct on the VRO leaking into the crankcase. Not fixed yet but I have a smoking gun to focus on. I am planning to get a rebuild kit for the VRO and see how that works unless you had another thought.

[Joe Reeves]

Joe I pulled #3 carb and I went in to check the reed valves in #3 incase one was broken. They looked fine and I decided to crank the engine to see them operate properly. Guess what I found, fuel pouring from the notch below the far right reed.

And I mean pouring out the hole. So despite the primer bulb test being negative it still seems like you were correct on the VRO leaking into the crankcase. Not fixed yet but I have a smoking gun to focus on. I am planning to get a rebuild kit for the VRO and see how that works unless you had another thought.

I assume that "notch" leads to the pressure hose of the VRO? If so... yeah, the VRO would be the culprit... BUT... I can't understand why fuel didn't run down that hose when it was off and you pumped up the fuel primer bulb. I don't remember the internal workings of the VRO's as they were changed/upgraded so often. At any rate... a learning experience for both of us. Keep me advised.

[scottro]

I assume that "notch" leads to the pressure hose of the VRO? If so... yeah, the VRO would be the culprit... BUT... I can't understand why fuel didn't run down that hose when it was off and you pumped up the fuel primer bulb. I don't remember the internal workings of the VRO's as they were changed/upgraded so often. At any rate... a learning experience for both of us. Keep me advised.

Joe I pulled the VRO and found no sign of fuel in the crankcase pump section of the VRO and could not find any problems with the VRO seals. I quit working on it because it was too hot and I had a long week. I am going to start on it tomorrow morning. I think the fuel was filling the bottom of the crankcase and was squirting up thru the small notch in the reed assembly from the crankcase pressure. I cannot think of any other way the fuel got in unless somehow the primer solenoid is leaking but only into the #3 carb. Not sure that is a viable theory.

[scottro]

I decided to apply approx. 5 psi to the crankcase pump section of the VRO to test for leaks and there was no sign of air leaking from the crankcase section of the pump. I could hear the spring operating and diaphram moving and still no sign of leaks. I don't think the carb is dumping fuel since I have tried 2 carbs on this cylinder.

[Joe Reeves]

Well... I really don't know what to say, BUT... having fuel flow out of some notch directly into the #3 reed plate area is certainly going to interfere with the operation of #3 carburetor to my way of thinking but obviously that excess fuel isn't a VRO diaphragm/pressure line problem.

I'd suggest taking this explanation of this encounter over to MarineEnginecom for the members there to kick around. Perhaps one of them has run into it at one time or another.

My only comment in thinking it over is that the fuel would be draining down from a higher cylinder... but why only when the engine is being cranked over? Mystery!

[scottro]

Well... I really don't know what to say, BUT... having fuel flow out of some notch directly into the #3 reed plate area is certainly going to interfere with the operation of #3 carburetor to my way of thinking but obviously that excess fuel isn't a VRO diaphragm/pressure line problem.

I'd suggest taking this explanation of this encounter over to MarineEnginecom for the members there to kick around. Perhaps one of them has run into it at one time or another.

My only comment in thinking it over is that the fuel would be draining down from a higher cylinder... but why only when the engine is being cranked over? Mystery!

So I went back to basics and started to lean out the #3 carb since the plug was wet an I had fuel in the crankcase. I kept turning in the idle screw in 1/4 turns and after approx. 1 1/2 turns I noticed a change in the idle. I pulled that plug and the engine responded for the first time I think I was just flooding that cylinder the whole darn time. I must have been playing with that carb during the no spark problem and forgot to re-tune it once the spark problem was resolved.

There is only one adjustment screw. I am not sure if that setting would also flood it at full throttle or only at idle. But I throttled up and it was much snappier than before the adjustment. I will try to get it in the water today and run it to verify operation. I will update when I am done.

[Joe Reeves]

Year, that would do it. That far out of adjustment would have canceled out the carburetor's function and knocked the cylinder out. The drop down test of pulling the plug wire off proved that.

[scottro]

I took ti to the river for a test run an found a bad storm had hit that morning upstream and the river was roaring with trees, and even a dock going downstream. So I backed in the ramp and ran the motor on the trailer. I ran perfect. The idle was 800 rpm and when I went to full throttle it ran up to 3600 rpm despite being stationary the engine sounded great. Thanks Joe for your help.