Johnson 70hp ?
I picked up a used 20' pontoon this spring w/ a 70hp 2-stroke(9/2000). Ran a little rough from winter layup, had a hard time coming up on all three cylinders, so I went and gave a tune-up changed fuel filter, plugs, new fuel line from tank w/primer bulb. Ran good but had a hard time to stay idling and when you shift into gear, forward or reverse, it stall out at times.
I pulled the carbs off to check over and clean(they were but cleaned them anyway to be sure) but the problem keeps getting worse, especially as it has warmed up here in Michigan. I have adjusted the idle screws to factory spec of 2 3/4 turns from lightly seated and had tried them in varying settings of about 1/2 a turn.
Here is what it does:
Cold start
-starts up and idles about 1000-1100rpms
-put in reverse to back out of slip drops down to 700rpms or so then stalls --engine seems to run rough(shakes)
-bugger to get re-started have to rev to up and then hurry to drop into gear to keep from stalling again( I know not good on rest of drive)
- if I can keep it from stalling out runs great all the way out to wot
- if I start to drop rpm's below 2000rpm's for cruising to about 1200rpm's and it will start to run rough(shakes) and sounds like dropping out cylinder and then stalls out
-will not idle on its own
Engine warm now
-will not fire if it does stalls
-try activating the 'Electic Fuel Primer' sometimes works sometimes does(ran some tests and it needs to be replace/rebuilt)
-if I do get it going I need to have it rev'd up like before and drop in gear at a high enough rpms to keep from stalling(I know....)
-will not idle on its own
-I have tested the temp sensor but did'nt affect operation
-plugs look all the same and look normal good color
Talked with owner and it and its never been touched since he's owned it, I know him and believe him.
Kinda at my wits end on which way to go with it and season will be over soon enough here
Any advise?
Thanks
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