1969 115hp has power but sputters and not smooth acceration, can it be bad pump fuel?

[adam98]

I have a 1969 v4 115 johnson that i have had for a few months, Ran great for the first 8 trips and 25gal of fuel.... i always put 91 in take but last week i put 8 gal of 87 in it and latter that day i ran into some problems. now it runs, but not very smooth. acceration is there but kinda spudders randomly. gets to wot but not smooth, runs fine a low rpm and idle, wont hold steady wot rpm tone...changed plugs did de carb, and drained carbs but still same problem. I live in california if that helps. i will always run 91 after this but do you think all 87 would cause so much problems? or is this just bad gas?

 

[adam98]

Re: 1969 115hp has power but sputters and not smooth acceration, can it be bad pump f

Would octane booster salvage the fuel in the tank?

 

[rockyrude]

Re: 1969 115hp has power but sputters and not smooth acceration, can it be bad pump f

That motor was designed to run on 87 octane, you might have gotten some water getting picked up.

 

[adam98]

Re: 1969 115hp has power but sputters and not smooth acceration, can it be bad pump f

Ok so today I drained the fuel tank.. No water or crud in it. I left it out in jugs to use later, and Then I filled it with fresh 91 from 76 gas station. I got it on the lake today and still surges at all rpm except idle. I'm guessing it's a fuel pump or spark cutting. It runs more then it cuts out I'd say is the ratio per every few seconds 80/20. It runs smooth/great in the driveway at all rpm.
Could my fuel pump be bad or need service? Could a jet be clogged? Could the ignition be cutting out? Is there a clog in the carbs? Could a Reed pedal broken?

 

[rockyrude]

Re: 1969 115hp has power but sputters and not smooth acceration, can it be bad pump f

My guess would be dirty high speed jets first, they always run good in the driveway but when you put back pressure on them (in the water) is when the gremlins show up. If you haven't done it in a long time, I'd clean and rebuild the carbs first.