90hp 88 Johnson Please help poor running

sertommy

Cadet
Joined
Apr 30, 2007
Messages
8
Just bought a used bought (private owner) it has a 90hp vro 1988 johnson and had it to the lake 1st time this year and problems are as follows Had a little trouble getting started, once started was missing and wanted to stahl unless adding slight throttle, said what the Hell maybe it'll clear up idled to behind breakwall and slowly throttled to WOT the boat barely got up on plane (after like a minute of WOT) once planed out seemed like it was slowly losing power so backed off quickly and stahl..Motor was hard to start again cranking like an old beat up pickup finally restarted still running poorly tried to open it up again and had almost no power than buzzer started going off kind of speratically wasn't constant at this point had good water stream from pee hole any throttle alarm got louder and more constant and boat would stahl....idling back to dock no alarm if kept at low throttle (no wake speed) pulled the boat got home.....Checked compression had 118-120 per cylinder, pulled plugs looked ok had brother crank while looking at spark from plug to bolt on engine block looked evenly firey on all plugs.....IM LOST PLEASE HELP ME. Boats an 18 ft glass center console. ANY HELP GREATLY APPRECIATED
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: 90hp 88 Johnson Please help poor running

Has the motor sat for a while without being ran? If so you should replace the impeller, plugs, rebuild the carbs and fuel pump for a start.
 

sertommy

Cadet
Joined
Apr 30, 2007
Messages
8
Re: 90hp 88 Johnson Please help poor running

Has the motor sat for a while without being ran? If so you should replace the impeller, plugs, rebuild the carbs and fuel pump for a start.

With exception of rebuilding all those things how would i test to see if any are bad
 

tashasdaddy

Honorary Moderator Emeritus
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sertommy

Cadet
Joined
Apr 30, 2007
Messages
8
Re: 90hp 88 Johnson Please help poor running

i have the same engine. you don't. start with the carbs. sounds like the are pretty cruddy. you will have to pull all jets, and need a special tool to get them out. then replace the plugs that covers them. all in rebuild kit. carb tool can be made from quality screwdriver. http://i155.photobucket.com/albums/s311/frankr_photos/FixedJetScrewdriver2.jpg?t=1177353186

Is there any possible imaginable way this thing could run this bad from poor fuel (i may be up to 1yr old)
 
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