Help with Johnson 115???

[aka_therebel]

I have a 1974 115hp Johnson that is giving me fits. It will run fine on muffs (sometimes) but it is very irratic. I put a new power pack on it and it seemed to run good so we took it out today. Put it in the water it started right up, idled out to open water and came right up on plane and seemed to run well for 10 to 15 minutes then died when I throttled back. Took forever to get it to run well enough to get in gear and go, I had to play with the choke to keep it going then it took off untill I throttled back again to go to the ramps. Now it wont idle without being a super high idle and it sounds like its only running on half the cylinders at lower RPM but if you bring the RPM up it smooths out. The carbs have been gone through, it seems to be getting plenty of gas since it started to puddle under the front of the motor, I assume from choking the crap out of it to keep it going. Pulled the plugs out and check spark on all 4 cylinders and they all have good spark. I checked resistance on the trigger and it is within specs. I dont have a DVA to check the stator but from what I have read I dont think that would be the problem. Any help wold be greatly appriciated!

 

[barnaclebill]

If you had to play with the choke to keep it running then it sounds more like a fuel problem.

Start with the simple items first. Pull a fuel sample out and make sure its ok. Todays fuels suck and are causing all kinds of problems. Compression test the outboard. Get a pair of home fuse pullers and start the outboard up. Pull one spark plug wire off at a time and see if the RPM's drop down the same for all cylinders. The cylinders that make no change are your problem cylinders.

 

[aka_therebel]

Sorry I forgot to add the compression on all 4 cylinders is 120 psi. The fuel has been changed also.

I did as you said and there is no change with cylinders 1 and 2 but 3 and 4 kill the motor if pulled. The top carb supplies the top 2 cyliners correct?

If it was the trigger (timer base) it would be 1 and 3 or 2 and 4 correct?

** Checked voltages on trigger(timer base) and stator when cranking and they all seem in spec.**

 

[barnaclebill]

Yes top carb does 1 and 2.

 

[aka_therebel]

Thanks for your help, I will pull them off again and go through them and see if there is something plugging it up.

 

[mateman]

Just thought. Check the line that feeds the top carb. Make sure its not collapsing or sucking air.

 

[aka_therebel]

ok pulled the top carb and dissasebled and checked everything and blew air through all the passages. I didnt see anything out of the ordinary but when I put it back on and fired it up problem solved!! Must have had some dirt in it. Thanks to all you guys for the help!!

 

[barnaclebill]

I redo alot of carbs in a years time and half of them look ok by the eye but work great once they are back together.

mateman that is a great item to check. I have pinched these lines while installing the air box. Can really drive you nuts.

Since we are talking fuel its very important today to keep a eye on fuel filters and fuel lines. This E10 crap is eating fuel lines, balls, and gaskets. If you feel any spot on your fuel line that feels different then the rest then its breaking down inside and needs to be changed. Feel all your fuel lines. Even the smaller ones going to your carbs, and pumps.

 

[aka_therebel]

Thanks for the advice on that. I changed all the lines on the motor, but didnt think about the main line from the tank or the balls. I just got back from the lake and it runs great for a motor that hasnt seen water since 1994..lol It will put you back in the seat on that little V-mate I. Big difference from the 75hp I took off that only ran on 2 cylinders..