90hp Johnson cutting out

[drhdres]

I have a 95 70hp Johnson 2 stroke that starts cutting out if i run it at WOT more than about 3 minutes. If i shut it down and wait until I stop and restart it it fires right back up and runs fine. As long as i hold it just under WOT I don't have a problem. It doesn't appear that I have a loose fuel line but does anyone have a suggestion?

 

[tashasdaddy]

Re: 90hp Johnson cutting out

clogging high speed jets, link n sinc.

 

[drhdres]

Re: 90hp Johnson cutting out

Sorry I'm pretty much a novice but I don't know what "clogging high speed jets, link n sinc" means.

 

[Demolitron]

Re: 90hp Johnson cutting out

The 'jet' is referring to the part of the carb that meters fuel depending on the air velocity moving through the venturi. If this is clogged, or damaged then it would lead to incorrect fuel/air mixtures. For info on carbs here http://auto.howstuffworks.com/question377.htm

The link 'n sync:

As you advance the throttle control the ignition timing advances while at the same time the carb butterflies open. It is critical that the two are in sync or in phase. The advance must track the butterflies exactly and at the right time.

I don't know how to do it on your engine but it shouldn't be too hard, just fiddly. Be sure to get a service manual for it.

 

[drhdres]

Re: 90hp Johnson cutting out

Thanks for the suggestion. I'll start fiddlin

 

[HighTrim]

Re: 90hp Johnson cutting out

Im going to agree with Demo, get yourself a manual, it will pay for itself a million times over, rebuilding a carb is fairly easy, bit harder the first time without a manual though. This video should help a bit.

"http://www.meegsonline.com/tmd/TMDsVideoChronicle2.wmv"

 

[guy74]

Re: 90hp Johnson cutting out

Sounds more like a weak fuel pump or a restriction in the fuel line to me. Clogged jets cause immediate cutting out, not 3 minutes later. Sounds like the fuel delivery can't keep up with the demand at WOT. With those symptoms it sounds like you are running te float bowls dry.

 

[_brad_]

Re: 90hp Johnson cutting out

Sounds more like a weak fuel pump or a restriction in the fuel line to me. Clogged jets cause immediate cutting out, not 3 minutes later. Sounds like the fuel delivery can't keep up with the demand at WOT. With those symptoms it sounds like you are running te float bowls dry.

I agree; I have the SAME problem with my 1977 70 HP Evinrude and I'm pretty sure its the fuel pump.. Carb bowls empty quicker than their getting refilled..

 

[drhdres]

Re: 90hp Johnson cutting out

Thanks for the suggestions, especially the video. This boat sat for about 4 years before I got it and put it in the water. I tried to clean everything up short of rebuilding the carb. I do need to get the manual for this one and I'll start with the fuel pump and carb.