prv
Well-Known Member
Well, as stated in post #14, my bladder was intact, I replaced it anyway, and it didn't cure anything
Pete
Grr - I hate small petrol engines! (Johnson 4hp 2-stroke)
- Thread starter prv
- Start date
Well, as stated in post #14, my bladder was intact, I replaced it anyway, and it didn't cure anything
Pete
mawm
Well-Known Member
I'm sorry to hear that. Mine had the same symptoms as yours and it did take some time for me to find the problem. Just trying to help.
ronsurf
Well-Known Member
Or a lifetime of coaxing Vespas and Lambrettas back to life!
Check the needle valve is operating properly. There was a thread here where the problem was caused by incorrect reassembly of the float valve. The float may be sticking as well
FulmarJeddo
Well-Known Member
This seems very similar to issues I had with an old Johnson 40hp years ago. We had problems with a blocked jet in the carb that turned out to be under a core plug, so took some finding. It still wouldn't run properly. We had already changed the spark plugs (replaced Champion with Champion), but were advised to fit NGK plugs. A new set of NGKs solved the running issues. It would seem the Champion plugs were breaking down when they got hot.
I would doubt that your issue is in the ignition coil, looking at the parts diagrams on the web yours has 2 coils in one lump. Its unlikely that both coils would break down together and you would expect a twin cylinder engine to continue to run on one cylinder, albeit roughly. However there is also the ignition module that controls the timing. I don't know an easy way to test that, and it's an expensive part to replace "just in case" (I have a dead Mercury 8hp in my garage that I suspect the ignition module).
The fact that it runs for a while then cuts out would point away from a blocked jet unless there's debris floating around, but you mentioned using carb spray. I have recently fixed a problem on a Mariner 6hp 4 stoke that would only run with the choke out. I had previously cleaned all the jets with carb spray and not fixed it. 2nd attempt I discovered the main jet although at first glance appeared to be clear was partly restricted and I could only clear it with a sewing needle.
I would doubt that your issue is in the ignition coil, looking at the parts diagrams on the web yours has 2 coils in one lump. Its unlikely that both coils would break down together and you would expect a twin cylinder engine to continue to run on one cylinder, albeit roughly. However there is also the ignition module that controls the timing. I don't know an easy way to test that, and it's an expensive part to replace "just in case" (I have a dead Mercury 8hp in my garage that I suspect the ignition module).
The fact that it runs for a while then cuts out would point away from a blocked jet unless there's debris floating around, but you mentioned using carb spray. I have recently fixed a problem on a Mariner 6hp 4 stoke that would only run with the choke out. I had previously cleaned all the jets with carb spray and not fixed it. 2nd attempt I discovered the main jet although at first glance appeared to be clear was partly restricted and I could only clear it with a sewing needle.
Stemar
Well-Known Member
I had similar issues with a Tohatsu 3.5. After stripping the carb 3 times and cleaning anything that moved - or didn't - to within an inch of its life and tearing out most of what little hair I had left, I was no further forward until a mate noticed a barely audible ticking. Investigation showed that the HT earth from the coil was connected to a ring conector under a bolt on the engine and this was corroded. The ticking was the HT sparking to earth 'cos it couldn't get there the normal way. A good clean of the connection and a dose of ACF50 cured the problem.
Good luck!
Good luck!
