1997 90HP SPL max's out at 3000 RPM in gear in water

[tynojennat]

I have a 90HP SPL that has run great since buying new in 97 with only VERY minor issues. Last weekend, after sitting for ~10 months, engine started great in yard with muffs and purred like a kitten. I was sure to top off the tank with freash new gas and oil on top of the ~1/4 tank that was in there before starting. Put the boat in the water, started great, idled great, put it in gear and slowly idled out of the inlet (fairly long ways - ~ 1/4 mile), did fine, but when I pushed the throttle down it would not plane and it topped out at exactly 3000RPM. I took it out of gear and it reaches 5500RPM no problem and holds there fine (of course I only kept it there briefly). I tried reverse and same thing, 3000RPM under load. I removed the cover and made sure I was getting full travel of the linkages and they were fine. Back on the trailer I pulled the plugs and they were black but not in real bad shape. I will be replcing the plugs and wires to see if that helps just in case, but they do not "look" bad, last replaced ~5 years ago. Thoughts? Rebuid Carb? Any thoughts would be greatly appreciated!

Be Blessed!

 

[Daviet]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

I would check the spark and compression on all cylinders to make sure that you are running on all cylinders. If those check out OK, move on to the fuel system.

 

[tynojennat]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Thanks! Yes, I am starting with ignition and compression and will then move on to fuel.

 

[boobie]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Keep on reving it to 5500 rpm in neutral and you'll have more probs. It's not running on all the cyls when under power.

 

[tynojennat]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

I couldn't agree more, I only revved it that high once to ake sure it wasn't a linkage issue. I just finished up checking over the ignition system and I did find corrosion on two of the lower cylinder coils. I cleaned all coil terminals and spark plugs. I have good compression on all cylinders and the spark jumps well over a half inch back to the head. I reset all of the plug gaps, made sure I had good spark through all plugs, and reinstalled eveything, engine fired great and idled fine. I then took the cover off the carbs and sprayed gumout carb cleaner all around, started the engine (with water on of course), and sprayed cleaner in the carbs as directed on the can...the engine smoked some as it burned through and everything seamed fine. Then I shut the motor off for a while and when I tried to restart, the motor didn't want to turn over. Battery was fully charged, so that was not the issue, it just didn't want to turn over and start. I took all of the plugs out and blew the cylinders out, put the plugs back in and it started fine. I let it run for over 20 minutes and now it seems fine, shuts off and restarts normal. I guess the next step is to put her back in the water and see what happens when I try to plane her out.

 

[Daviet]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Let us know how it runs when you get it in the water.

 

[boobie]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

When you get it in the water and if it acts up again, pull one plug wire at a time and see if you can narrow it down to a cyl.

 

[1FASTLASER]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

You stated it sat for 10 months. I would be looking at the fuel system if the mmotor in fact ran fine last time out. Today's fuel if allowed to sit very long will go the through phase separation and you will end up with all sorts of deposits in the system that will clog jets etc etc....run a compression test,refuel with fresh fuel with a system cleaner such as Seafoam and go from there. Be carefully about using spray carb cleaner on 2 stroke outboards.

 

[archcycle]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Also get yourself a spark tester. They're about $5 at any auto store. It's very bad for your ignition system to have nowhere for the spark to go and a spark tester clips to a ground so you eliminate human error of holding it perfectly by the block. Also less shocks

 

[tynojennat]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Well, same thing is going on. At least now I know the following: I have spark at all four cylinders in the yard at idle; I have good compression on all four cylinders; I have good spark plugs with good fire through each. At the ramp today, the motor started right up, purred like a kitten as I putted out of the canal and then maxed out at 3,000RPM just like last weekend. I pulled the plug wires one at a time like suggested above and as suspected, only the top two cylinders appear to be firing. With each of the lower wires were off (idividually) there was no difference. But when one of the top wires was off there was a big difference. I'm at a loss, any thoughts?

 

[tynojennat]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

I did a lttile research about fuel additives and opted to try out the Starbrite StarTron brand. I added this to the tank this afternoon before putting it into the water.

 

[JDusza]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Nailed it!
Problems with bottom cylinders.
Not spark? Fuel delivery.
Main jets clogged.
Inlet needle valve stuck closed.
Blow some carb and choke cleaner through the carburetor's fuel inlet with the little red straw on the can's nozzle.

 

[tynojennat]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Now we are entering a realm I know little about. When I take the cover off the carbs, there are straight brass tubes in each of the four inlets. Are these the main "Jets?" I'm gonna see if I can find an exploded view of my fuel system. Thanks for the info!!

 

[tynojennat]

Re: 1997 90HP SPL max's out at 3000 RPM in gear in water

Well, it’s a month later, but the boat appears to be fixed!! I rebuilt the carbs last week and put it in the water for a quick test and it appears to be doing great. I think the float may have been stuck in the bottom carb, but they both seemed to be a little gummed up in the bowls. Thanks again for the help. Now just need to find more TIME to spend on the water!!