Johnson '82.150 engine power

[sruman]

I have a '82 150hp that I'm having several problems with. First, it has no punch out of the hole. Very doggy, but once it get the rpm's up, it seems to run okay (engine runs smooth). I think it could be because the prop is has too much pitch (14.5 x 23p). Compression is fair 105-110 across all cylinders.
Here are the issues:
- idle is fast out of water
- tach only starts working at once engine is above 900 rpm's.
- no hole punch. It appears to be loading up. If I gradually get it going, and the rpm's and speed slowly increase the engine will eventually smooth out and take off.
- top end is only getting to 4200 rpm. Boat will plain very good once going. Engine is running smooth, but simply not up to par. It acts like I'm in 6th gear, and not enough power to get up to top rpms and speed (prop???).
Any ideas on what would be some good places to start? Should I start with electrical (would that cause a loss of power)?
I have a Astroglass 17', if that helps.
Thoughts?

 

[chadpcb]

Re: Johnson '82.150 engine power

Here are the issues:
- idle is fast out of water
- tach only starts working at once engine is above 900 rpm's.
- no hole punch. It appears to be loading up. If I gradually get it going, and the rpm's and speed slowly increase the engine will eventually smooth out and take off.
- top end is only getting to 4200 rpm. Boat will plain very good once going. Engine is running smooth, but simply not up to par.

Here is a couple of things to try.
At WOT try and pump your primer bulb. See if this helps. If not try your Choke and see if it helps. If the 2nd option helps you start at your fuel pump. Make sure it is functioning properly. If it is functioning properly then check and rebuild carbs.

By hit your choke you are by passing the carbs and dumping fuel into the cylinders.

Fast idle out of the water. It will rasie up about 400RPMs on a hose.

Tach is your tach starting at zero or at 900

Did you have a good hole shot before with the same prop?

 

[83ebbtide]

Re: Johnson '82.150 engine power

I have a 17' 6" boat with an 83 175 and am running a 21 pitch and its almost too much. I think your 23 is hurting your top end RPM's. I'm searching for my mystery boog as well. Rebuilt carbs and am now looking over the entire fuel system again. Look for fuel leaks when you pump the primer bulb like you would before starting the motor during launch. If you see any leaks fix them, you could be sucking in air. Check the primer bulb as well. Make sure it firms up when you pump it. If not change it. How long have you had the boat? Do you know when if the carbs have been rebuilt?

 

[jonesg]

Re: Johnson '82.150 engine power

I have a '82 150hp that I'm having several problems with. First, it has no punch out of the hole. Very doggy, but once it get the rpm's up, it seems to run okay (engine runs smooth). I think it could be because the prop is has too much pitch (14.5 x 23p). Compression is fair 105-110 across all cylinders.
Here are the issues:
- idle is fast out of water
- tach only starts working at once engine is above 900 rpm's.
- no hole punch. It appears to be loading up. If I gradually get it going, and the rpm's and speed slowly increase the engine will eventually smooth out and take off.
- top end is only getting to 4200 rpm. Boat will plain very good once going. Engine is running smooth, but simply not up to par. It acts like I'm in 6th gear, and not enough power to get up to top rpms and speed (prop???).
Any ideas on what would be some good places to start? Should I start with electrical (would that cause a loss of power)?
I have a Astroglass 17', if that helps.
Thoughts?

I have a 14x19 on my 150, you're way over propped and luggin it.

 

[sruman]

Re: Johnson '82.150 engine power

the carb's were just recently rebuilt (this year). My biggest concerns are that prop pitch is too high, and I don't have the power to get to top end. When running WOT, the engine is smooth, but seems it "feels" like I have a governer on it. Doesn't miss fire, surge, etc.
I'm going to give the bulb test and choke test tomorrow, I'll let you know how I make out. If that doesn't help, I'm going to look at a 19 pitch prop. Is that a good choice? If so, what manufacturer makes the best prop (am I allowed to ask that on this forum?).

 

[chadpcb]

Re: Johnson '82.150 engine power

Here is the recommended props for that motor.

P/N Prop Size
387158 PROPELLER, 15-1/2 x 13
387159 PROPELLER, 15-1/2 x 15
387160 PROPELLER, 15 x 17
391200 PROPELLER, 15 x 17 std. 150, 175
387161 PROPELLER, 14-1/2 x 19
391201 PROPELLER, 14-1/2 x 19 Std. 200
391202 PROPELLER, 14-1/4 x 21 Std. 235
387163 PROPELLER, 14-1/4 x 23
389925 PROPELLER, 15 x 16 SST
389924 PROPELLER, 14-1/2 x 19 SST
389923 PROPELLER, 14-1/4 x 21 SST
389019 PROPELLER, 14-1/4 x 23 SST
387995 PROPELLER, 14-1/2 x 24 SSTR
387996 PROPELLER, 14-1/2 x 26 SSTR
387997 PROPELLER, 14-1/2 x 28 SSTR
390725 PROPELLER, 14 x 25 SST
390831 PROPELLER, 15-1/2 x 14 SST

It is best if you went to a dealer and looked at a Spec Chart for props on the length and weight of your boat.

 

[jonesg]

Re: Johnson '82.150 engine power

Try the experts on the prop forum.
http://forums.iboats.com/forumdisplay.php?f=35