1977 Johnson 115 WoT & bogging-down

[polvaultr]

This is a 2-part question.

1. What is the WoT rpm's I should be looking for? I have it on a 17' Renken Bowrider. No clue on the prop as it was already in place when I got the boat/motor. I took her out today and was running 31mph @ ~4k rpm. Due to my previous ventures with her, I was ecstatic to get past the dock as we had a local shop do a tune-up last fall.

2. After running about 15 min, we dropped anchor to do some fishing & swimming. Ok, so we did some casting and swimming. After we were ready to move spots, she would fire up for a few seconds, maxing at about 1k idle and die as soon as I would put it in gear. I'm thinking its old gas fouling the plugs (I haven't looked at them yet, too frustrated after I got home), but she fired right up after a few tries with muffs on the trailer. I know everyone suffers the "tow of shame," but I felt really bad for the nice couple that gave us the 1.5 hr tow back to the ramp.

Any thoughts would be greatly appreciated!

 

[1983 ercoa 21']

Max rpm are right around 5500 if proped correctly.
try pumping the bulb and see if it picks up and runs if so you have a fuel delivery issue that could be the fuel pump and or a leaking line that could be sucking air.
you could also have a vent on the tank pluged or you didn't open it.
you can do some simple test in your driveway starting with a
compression test
cylinder drop test while running on the muffs if you find one not firing do a
spark test jumping a 7/16 gap

 

[lower slower de.]

Ok took all the great advice that I got last week d Carmen the heads with spray seafoam then good compression test on a warmed up engine everything checked out all cylinders were between 115and120 grand great in the driveway put it in the water would barely idle and could not get max rpms oh also replaced all four coils thinking maybe now I have a fuel issue what's next

 

[lower slower de.]

Sorry should check voice spelling before I post 115and 120psi and ran great on the muffs in the driveway

 

[emdsapmgr]

The engine may not be running on all 4 cyls. If you use one of the two spark check methods in post # 2, that will tell you if you have spark to all 4 plugs. That engine will seem to run just fine when idling on the trailer in the back yard-when actually only running on 2 or 3 cyls. You need all 4 firing when it's in the water and in forward gear.