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99 Johnson missing at speed

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basstard123456

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I have a 99 Johnson 115 Produc

I have a 99 Johnson 115 Production date is 10/1998 Model J115PlEEM
Boat has never been in salt water.
I was making a long run with the boat about 14miles when I noticed a small but short misfire only every so often As the days went by it got worse & at first it was only under WOT but now its at half throttle or sometimes as I am trying to get on plane.
I thought I had got bad gas & I put some Sea foam in the tank the next day it was just as bad if not worse.
I did lot of reading on here & saw lot of boat with similar problems but I have not formed a plan of attack just yet.
First checking to see if it is an over heat problem the suggest to remove the brown wire & ground it to see if the over heat horn sounds I have a light not a horn but yes it works so that eliminates heat.
I have about every gauge & light a bass boat could on this ride.
I Pulled the fuel filter or what I would call a screen It seemed to be fine no major clogging Are there more filters??
I removed the plugs all look good & did a compression test 90+ on all 4
I did find one of the seal rings missing on the air box so that explained the small amount of oil in motor compartment.
Next test I guess would be to take it on the water & try pumping the ball when it happens but it will be hard to tell because it happens but then recovers very fast.
I have heard that the fuel pumps on these can go bad but again it feels like a spark misfire.
I have been a car mechanic for 20+ year so I am no stranger to engines I would like to diagnose & not just put parts on till its fixed.
 
"there should be another inlin

"there should be another inline filter under the cowl ,follow the feed up from the connection.
do a spark jump test they should all jump 7/16
of an inch with a strong blue arc"
 
"what u r experiencing,..is id

"what u r experiencing,..is idicative,of a loose,or cracked timer wheel,or loose optical sensor...remove top covers to ck both.."
 
Ok I followed the fuel line &a

Ok I followed the fuel line & there is no sign of a filter & I dont see one listed in any parts list.
I removed the top covers I see no cracks on what I would assume is the timer wheel I have not got my service manual yet so I am not sure what I am looking at. I see the timing advance adjuster & to that is a sensor plug that has 5 wires. All plugs on the wires seem to be tight.
Should the primer ball stay hard over night I pumped it up & now its soft again just sitting over night.
 
"back 2 basics ,the primer bul

"back 2 basics ,the primer bulb will not stay hard over night in order to time that model correctly an omc analyzer is the ticket.you can build one yourself for about 25bucks surging while its running could be many things dont be fooled leak in fuel line,improperly adjusted carb,cold start circuit,vaccum leak,float adjustmentetc.. check & recheck everything....."
 
the decision is:is it electric

the decision is:is it electrical or fuel?i would strongly recommend the spark test as Charles Harris suggests...if you do not get the spark then fix that..that may end up pointing to a faulty component to fix the problem..i carry an inductive timing light in my tool box on the boat....pick a plug and install light..tape the trigger back so you can see the light pulsing while running...this actually is a little easier with 2 people in the boat but works on if the lead is long enough for you to place the light where you can see it easily...the goal is to either point to electrical problem or eliminate it..if its getting worse i would suspect timer base or stator or power pack..stator on that model...i assume gas is new gas...if you are using a built in gas tank then i would put the motor on a portable 6 gallon tank to eliminate water in gas as the problem...make sure air filter is clean on tank...make sure the hose connector that connects to the motor has a good oring in it and that it snaps in place...just pushing it all the way in wont cut it..make sure the retaining clip snaps into the groove..back to the spark test for a moment...you can make one with 2 nails thru a piece of wood...then bend the nails to the gap you want to jump...either use 2 nails or 5 if you wish to do all at once.that sparkshould be blue..not orange...and a real snap to it...
 
Ok I got it out this weekend f

Ok I got it out this weekend for a test. First run was about 3miles & it did not have a problem. I thought wow I might have fixed it when I cleaned the small amount of stuff out of the fuel filter. I fished for about 1/2hr & when I made next run it started cutting out We hooked up the timing light & yes it would stop flashing when the cut out happen. After that we stopped again to fish & when we started up again it was real bad I could not get on plane had 0 power only could go idle speed. We tried pumping the primer ball at that point & it did not fix so fuel pump is good .Stopped the engine for 3 hrs & it ran good after that on a short run. So its heat related & that points to electrical My first guess is the Coil is there an ohms test for that? IF so I bet it will pass until i heat it up I have seen this before on cars were it will run great then when the coil get hot BAM.
Carl stated "make sure the hose connector that connects to the motor has a good oring in it and that it snaps in place...just pushing it all the way in wont cut it"
Sorry but I don't have a connection like that the line is not removable via a clip like you might see on small HP motors so putting a external tank on is not easy.
 
Just an update Boat is fixed I

Just an update Boat is fixed It was the Power pack replace it & also did the coils because I got free shipping if my over a amount so was it like I got 1 coil free so what the heck.
Thanks all for the input now back to fishing.
 
basstard123456 said:
Just an update Boat is fixed I

Just an update Boat is fixed It was the Power pack replace it & also did the coils because I got free shipping if my over a amount so was it like I got 1 coil free so what the heck.
Thanks all for the input now back to fishing.
Click to expand...
If you're still around, did the old pack look fine? My 99 is doing the same thing and the power pack "looks" perfect and I don't know if it would be something visible if bad. Lot of money to spend if nothing is wrong with it
 
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