1977 85hp Johnson wont go over 2500 rpms when in gear

[dakota7569]

Need some expert advise. I bought a boat and took it in to have it made ready for the year. They put a new impeller, new spark plugs, flushed old gas out, ran a couple bottles of carb clean through it. It ran great for them in the shop. I took it too the lake. It started up. Had great throttle response. Revs up in neutral to 5000-7000 rpms. I put it in gear to cruise arond the lake,. It feel like the parking brake is on. I putted arond the lake never getting over 2500 rpms. I call them and they think it sounds like a power pack is bad. Am I being led in the right direction? How much will something like that cost me to have fixed? This is my first boat and I am not very savvy at this. Any help is much appreciated!

 

[boobie]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

Keep on reving it to 5000 to 7000 rpm in neutral and you won't have any probs with that mtr. Just have to get another one. Take it back and let them check it out. Get a quote from them.

 

[drumz2129]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

What boobie said - Do not rev your motor that high with no load on it.

The shop is probably right. I just went through the same thing with a '78 70hp I brought back to life. It ran great on the muffs, great from the launch to the river. But when I would try to get on plane it would try to rev then just fall on it's face. I brought it home an checked fire to each cylinder. Cyl #1 had no spark, I tested and swapped coils around, then the same with the triggers in the timer base and all signs pointed to the power pack.

Your first thing should be to test for spark at each cylinder and go from there.

If you pay retail expect to pay $130-150, I paid 70$ with free shipping for my new PP. It is easy to change on that motor (though not as easy as the newer ones with quick disconnect plugs). 4 bolts hold the cover on, under it are 11 wires that are screwed to the PP, all are labeled, and 2 bolts hold the PP to the motor.

 

[bishopcherrycoke]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

I had this same problem with mine last year. It revved just fine in neutral but wouldn't go past half throttle in gear. It turned out that when I put the cowl on, I ripped out a spark plug wire. Hopefully it is something this simple with your motor. Don't rev it that high in neutral though. You can damage your motor.

 

[emdsapmgr]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

That engine will seem to run just fine on the trailer, with only 3 cyls. firing. You need all 4 cyls contributing to get top performance when the boat is floating in the lake. While the power pack is the most common failure ignition component on a statistical basis, it's also expensive. There are also other ignition components which could fail-also expensive. Best to do some ignition troubleshooting prior to purchasing parts-it'll save you $ in the long run. You can find good ignition troubleshooting info on the web at: cdielectronics.com

 

[5150abf]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

Spark or dirty carb, that is a pretty classic sounding plugged high speed jet, shouldn't be hard to sort out

 

[Blacksting]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

Spark or dirty carb, that is a pretty classic sounding plugged high speed jet, shouldn't be hard to sort out

+2,....why go the expensive route before cleaning the carbs ?

 

[dakota7569]

Re: 1977 85hp Johnson wont go over 2500 rpms when in gear

Ok. I took it back to the shop. He took it out says it ran great. My brother picked the boat up took it to the lake. He said it did the same thing for a little bit then. She kicked in and it ran great. Around 30 mph. I took it out today did the same thing ran like crap and one time she kicked in and got up and went. We went home put muffs on her and start pulling plugs. We pulled plug 1 no change in motor same with #3. we open the power pack and cleaned connection they all looked good. Started it back up did the same thing.. ran on 2 cylinders. Took a wrench rapped on the power pack. Boom she picked up all 4 cylinders were running. So as a ham and eggers, we belive the power pack is bad. I just found it online at NAPA part # 18-5753 for $145

1. you think we are on the right path?
2. if so where should I have purchased it.

You are right it looks pretty easy to replace. Thank you guys for all helping.

What boobie said - Do not rev your motor that high with no load on it.

The shop is probably right. I just went through the same thing with a '78 70hp I brought back to life. It ran great on the muffs, great from the launch to the river. But when I would try to get on plane it would try to rev then just fall on it's face. I brought it home an checked fire to each cylinder. Cyl #1 had no spark, I tested and swapped coils around, then the same with the triggers in the timer base and all signs pointed to the power pack.

Your first thing should be to test for spark at each cylinder and go from there.

If you pay retail expect to pay $130-150, I paid 70$ with free shipping for my new PP. It is easy to change on that motor (though not as easy as the newer ones with quick disconnect plugs). 4 bolts hold the cover on, under it are 11 wires that are screwed to the PP, all are labeled, and 2 bolts hold the PP to the motor.