70hp Johnson problem

[JerzyDog]

I recently bought an old boat with a 1982 70hp Johnson.
It seems to run fine on the garden hose with muffs, revs up, goes into forward and reverse, all seems good. when put in the water, it starts right up, then as soon as I put it in gear, it dies. I thought it may be a weak fuel pump, so I replaced it, same results. Any ideas or suggestions?

 

[racerone]

They all sound just great on a hose to the untrained ear.-------Do a compression test first.---Then check for strong spark on each lead.-------Sounds like it might be running on 2 of 3 cylinders.

 

[fdrgator]

Could be as simple as idle speed adjustment (too slow).

 

[JerzyDog]

good spark and all 3 cylinders 96-101lbs compression

 

[JerzyDog]

adjusted it higher, didn't help.

 

[racerone]

My tester would show 140 psi on a good model like that.