1985 Johnson 150 bogging down

[Cpt.Kirk]

I have a 1985 Johnson 150. The engine idles great on a hose and in the water. But when I throttle down to get on pad the engine bogs down and will stall. If i throttle down and choke it before it stalls it will take off and run good. I say good because I can get 5000 rpm out of it but there is an intermittent hesitation. I feel it, more then I can hear it. Here's what I know and have done so far...as far as I can tell the bulb is holding pressure. I've taken off the carbs and cleaned them with little to no build up or fuel residue. (Did not rebuild, just cleaned them). Taken apart and inspected fuel pumps with no sign of a defect or problem. Now the big one...compression. Cylinders read 83, 80, 80, 75, 77 and 65. I do know that the 65 is not good. What I don't know is how bad this affects the motor. I'm assuming a new set of rings would fix the cylinder. Is the cylinder causing the bogging issue? I still think it's carbs or fuel pumps. Any input would be appreciated. Thanks guys!

 

[Bosunsmate]

Re: 1985 Johnson 150 bogging down

I have a 1985 Johnson 150. If i throttle down and choke it before it stalls it will take off and run good. Any input would be appreciated. Thanks guys!

How long will it run good for?

 

[Bosunsmate]

Re: 1985 Johnson 150 bogging down

Also how do your sparkplugs look? Are they all a similar colour?
Water getting into one cylinder through a worn gasket etc can cause an intermittent miss, the sparkplug will look clean if used recently or rusty if sat for a day or two or more

 

[Cpt.Kirk]

Re: 1985 Johnson 150 bogging down

Also how do your sparkplugs look? Are they all a similar colour?
Water getting into one cylinder through a worn gasket etc can cause an intermittent miss, the sparkplug will look clean if used recently or rusty if sat for a day or two or more

The motor has not quit running other then when I give it the gas. Once it's up and running, it runs good. All spark plugs look good with no sign of rust. I should note that I recently bought this boat. It's been three or more years since it's been in the water. But the previous owner would run a fresh gallon of gas through it every 6 months or so.

 

[emdsapmgr]

Re: 1985 Johnson 150 bogging down

You have not posted the model number of this powerhead. OMC made two types of 150's that year. The straight 150 and the high perf 150S-(the GT/XP version-about 165 actual crank hp.) The compression is lower on the normal 150. The basic 150 will have the stock 328324/325 heads, I'd expect compression to be about 90 on each cyl, plus or minus maybe 5 lbs. So, your compression is low to start with, and the 65 lb cyl could be a problem. Could be from sitting for a while, as you mentioned. I'd run a can of Bombardier Engine Tuner through the powerhead-according to the instructions on the can. Likely you will see the compression increase somewhat and probably idle much better. If the compression comes up a even a little, your compression numbers will be in the ballpark. If the low cyl is still more than 10% lower than the rest, you need to have a look inside. 1. Shine a pencil flashlight into the low cyl and visually inspect. Check the piston crown for pits. Check the cyl side walls for scuffing. 2. If you see anything unusual pull that head. 3. If you pull the head, move the piston around by hand at top dead center and see if you cant determine if the top ring is intact or not. (there should be enough slop in the piston-to-liner clearance for you to do this.) Pits on the top of the piston and underside of the head face are from pcs of the top piston ring-after it disintegrated. 4. You can pull the bypass cover off the low compression cyl and have a look at the ringsets. Look at the skirt of the piston to see if it has a carbon ring buildup on it. (the decarb process should start to eat away at any carbon ring.) If the engine runs normally at wot (5000 rpm's) it's unlikely the fuel pumps are bad. [Although that engine should be propped to run at least 5500 rpm's at wot.] The carb bowls on that engine have mid-range jets in addition to the idle and high speed ones. Possible one or more of them is plugged with debris-causing the midrange stumble you mentioned in your first post. When you pulled the carbs down for cleaning, did you pull all the jets out for a visual inspection for debris? - a must during any carb cleaning. That could be part of the problem.

 

[racerone]

Re: 1985 Johnson 150 bogging down

It will idle great on a hose running on 5 cylinders.--Start with a compression test here.

 

[Cpt.Kirk]

Re: 1985 Johnson 150 bogging down

You have not posted the model number of this powerhead. OMC made two types of 150's that year. The straight 150 and the high perf 150S-(the GT/XP version-about 165 actual crank hp.) The compression is lower on the normal 150. The basic 150 will have the stock 328324/325 heads, I'd expect compression to be about 90 on each cyl, plus or minus maybe 5 lbs. So, your compression is low to start with, and the 65 lb cyl could be a problem. Could be from sitting for a while, as you mentioned. I'd run a can of Bombardier Engine Tuner through the powerhead-according to the instructions on the can. Likely you will see the compression increase somewhat and probably idle much better. If the compression comes up a even a little, your compression numbers will be in the ballpark. If the low cyl is still more than 10% lower than the rest, you need to have a look inside. 1. Shine a pencil flashlight into the low cyl and visually inspect. Check the piston crown for pits. Check the cyl side walls for scuffing. 2. If you see anything unusual pull that head. 3. If you pull the head, move the piston around by hand at top dead center and see if you cant determine if the top ring is intact or not. (there should be enough slop in the piston-to-liner clearance for you to do this.) Pits on the top of the piston and underside of the head face are from pcs of the top piston ring-after it disintegrated. 4. You can pull the bypass cover off the low compression cyl and have a look at the ringsets. Look at the skirt of the piston to see if it has a carbon ring buildup on it. (the decarb process should start to eat away at any carbon ring.) If the engine runs normally at wot (5000 rpm's) it's unlikely the fuel pumps are bad. [Although that engine should be propped to run at least 5500 rpm's at wot.] The carb bowls on that engine have mid-range jets in addition to the idle and high speed ones. Possible one or more of them is plugged with debris-causing the midrange stumble you mentioned in your first post. When you pulled the carbs down for cleaning, did you pull all the jets out for a visual inspection for debris? - a must during any carb cleaning. That could be part of the problem.

I did not pull jets but I'll go back through thw carbs and do that. As well as check the cylinder. Thanks for your help. I'll let you know the verdict.

 

[Bosunsmate]

Re: 1985 Johnson 150 bogging down

I have a 1985 Johnson 150. The engine idles great on a hose and in the water. But when I throttle down to get on pad the engine bogs down and will stall. If i throttle down and choke it before it stalls it will take off and run good.

Just needing to clear a few things up..
From my reading of this you are idling high and you then drop it down to lower rpm, choke it, then throttle it and it goes ok. I dont get why you are throttling down before putting in gear to take off. You should be able to have it sitting at full retarded throttle (lowest idle)and then just go for it.

So is it idling ok with the throttle right back at low idle or does it only idle at higher throttle setting? Whats your rpm at lowest throttle idle setting?

Have you felt the heads to check they are very warm? Not cool or very hot? failed/stuck open thermostats can cause such a problem.

You say it has an intermittent miss but it runs good at wot, when exactly is the intermittent miss? At WOT? All throttle ranges?

 

[Cpt.Kirk]

Re: 1985 Johnson 150 bogging down

Just needing to clear a few things up..
From my reading of this you are idling high and you then drop it down to lower rpm, choke it, then throttle it and it goes ok. I dont get why you are throttling down before putting in gear to take off. You should be able to have it sitting at full retarded throttle (lowest idle)and then just go for it.

So is it idling ok with the throttle right back at low idle or does it only idle at higher throttle setting? Whats your rpm at lowest throttle idle setting?

Have you felt the heads to check they are very warm? Not cool or very hot? failed/stuck open thermostats can cause such a problem.

You say it has an intermittent miss but it runs good at wot, when exactly is the intermittent miss? At WOT? All throttle ranges?

The engine idles fine. (No apparent missing). Once I put it in gear (no wake speed) everything is fine. It's once I throttle down, (not using the fast idle) as you would normally, is when it begins to bog down. That's when I can choke it and the boat will plane out as normal. The surging happens throughout the throttle range, but this is very slight, and is felt most at wot.
I ran it on the hose for just a few minutes (3-5) yesterday and the piston heads did feel warm.

 

[Bosunsmate]

Re: 1985 Johnson 150 bogging down

Have you had someone pump the fuel bulb while its running idle to wot to act as a functioning fuel pump?

 

[Cpt.Kirk]

Re: 1985 Johnson 150 bogging down

No, haven't had the extra set of hands. It doesn't appear to be collapsing, though it's hard to tell.

I just talked to a guy who has a 1996 fast strike he is selling for $2,000. His boat was totaled from a tree that fell across the bow. The motor was not damaged. It was last run in June and he said it ran great. It has the hydraulic steering, hot foot pedal, I can even take all the gauges. What's your opinion guys...re-power or keep trying to fix a thirty year old motor?

P.S. As for my 1985 champion bass boat...sentimentally it's priceless to me. I don't ever plan on getting rid of the boat itself.

 

[Bosunsmate]

Re: 1985 Johnson 150 bogging down

Id keep the $2000 in my pocket as long as i could. See if you can fix your current one or find out if it has a fatal fault before he sells his one. Even half of that price would buy you a lot of parts.

You really need to do what is suggested above about cleaning the carbs, every jet and every hole you can see needs to be cleaned and checked for no blockage. Sometimes people just remove the jet and still have the same problem you mention. Its only when carb cleaner is blown through them do you realise that none is coming out of another hole and there is thus a blockage. I blow every hole with carb cleaner and run a soft copper wire down them. If carb cleaner isnt blowing through a hole and out another exit in the carb somewhere then i clean it until it does.
A little hesistation at all power ranges is very typical of a blockage somewhere in the carbs.

 

[emdsapmgr]

Re: 1985 Johnson 150 bogging down

The carb'd Faststrike is a fine engine. Lots of torque. Quieter than your current engine and maybe a little more fuel efficient. It's the performance model rated about 165 actual hp. Before you payout any $, I'd check compression, lower unit oil. See how it runs on his trailer first-before you buy it and remove it. I can't give you any idea if the price is ok or not. Depends on where you are and if it was used in saltwater or not.

 

[Bwil]

Did you ever fix the issue? I have same prob

 

[GA_Boater]

Did you ever fix the issue? I have same prob

For the 3rd and final time - You have a thread, use it. Old and closed.