Succotash
Active member
Any input would be greatly appreciated...
I've been working on a 76 Johnson 15hp short shaft, pull start. This engine had been sitting for 3+ years before I got my hands on it.
Problem:
It will run fine on muffs in my driveway. Starts on first pull, revs, pumps water great from pee hole...etc.
However, for some reason when I place the boat in the water I start to experience problems... At first it will start rather quickly (1 or 2 pulls with choke out) and run fine for a couple minutes. After moving the choke back to the IN position and applying a little throttle, it bogs down immediately. After which it is nearly impossible to get it started, and takes me several (10+) pulls to get it running again.
Once I finally get it running again, while holding any CONSTANT throttle position (in neutral) it will bog down after a few seconds. Although I have noticed that I can keep it running a lot longer if I continuously play with the choke (pulling out and pushing in).
Observations:
*Could be irrelevant, but lots of water coming from the exhaust relief holes under the powerhead while running.
*Somehow the increased back pressure of the lake severely effects this engine. Could it be a weak fuel pump? Or possibly an ignition problem? ](*,)
Things I've done:
Rebuilt the carburetor with new float
New fuel lines
New plugs (checked for spark by simply grounding out the plugs to the engine block)
New water pump (pumps great out of the tell tale)
New thermostat
New exhaust housing (original was cracked)
Inspected fuel pump (seemed to work well enough?)
I've been working on a 76 Johnson 15hp short shaft, pull start. This engine had been sitting for 3+ years before I got my hands on it.
Problem:
It will run fine on muffs in my driveway. Starts on first pull, revs, pumps water great from pee hole...etc.
However, for some reason when I place the boat in the water I start to experience problems... At first it will start rather quickly (1 or 2 pulls with choke out) and run fine for a couple minutes. After moving the choke back to the IN position and applying a little throttle, it bogs down immediately. After which it is nearly impossible to get it started, and takes me several (10+) pulls to get it running again.
Once I finally get it running again, while holding any CONSTANT throttle position (in neutral) it will bog down after a few seconds. Although I have noticed that I can keep it running a lot longer if I continuously play with the choke (pulling out and pushing in).
Observations:
*Could be irrelevant, but lots of water coming from the exhaust relief holes under the powerhead while running.
*Somehow the increased back pressure of the lake severely effects this engine. Could it be a weak fuel pump? Or possibly an ignition problem? ](*,)
Things I've done:
Rebuilt the carburetor with new float
New fuel lines
New plugs (checked for spark by simply grounding out the plugs to the engine block)
New water pump (pumps great out of the tell tale)
New thermostat
New exhaust housing (original was cracked)
Inspected fuel pump (seemed to work well enough?)