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No top end.

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Brian4591

Contributing Member
I have a 1996 225 evenrude on a 20' Stratos FS. The boat getts on plane very quick and easy but at top end I only get 48mph gps and 4800rms and if I trim more the prop blows out and max rpms is only 5100. Motor starts and runs fine but I feel that I should get way better top end. Even when prop blows out it sould over rev to about 6100rpms. I have changed pulugs from Chamion to Recumended NGK. The Champions were not even the right numbers for that motor and they were gaped at .040. New plugs are set at .030. I also checked coils and plug wires with oms meeter and the checked out good. Not sure where to go from here. I know lowering prop from a 23P Balistics is not the answer because the boat gets on plane very quick with little efort. I also checked carbs for WOT and they are all perfect. Help.
 
Do you fish and ski/tube or just fish?? If you just fish that the wrong prop... Need to try a 24 or 25 renegade as the Ballastc dont work well on boats that need a lot of bow lift. This due to the windshields act like elevators and hold the bow down.
 
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Whenever a looper like you have drops one thousand RPM (give or take) I always look first at the possibility of having one dead cylinder.

One cylinder not firing, or not contributing for some reason.

There is one quirky kink about these loopers that I have run into twice. It is rare, but worth looking into.

I have seen two instances where the engine starts, with QS active, and ten seconds later, when QS disengages, a cylinder drops out...quits firing.

One case it was cylinder #2, the other was cylinder #1. You would think this was power pack related, but no, it was the timerbase in both cases.

It is tricky, because when you do a spark test on these engines, QS IS ALWAYS ACTIVE.
I stumbled upon the fault simply because I put NEW plugs in, ran it, and pulled the plugs to read them. Number 2 was new looking, while all the rest were browning up nicely.

From then on, when I see a 1k drop in WOT, I put a timing light on each cylinder and watch the light until after QS disengages. Light will quit immediately when QS disengages, IF you have this problem. It can be done at idle.
 
That is what seems to be going on. Later today I will do the timing light. I have checked coil and wires with oms meeter and checked out good.
What about Stator. Can they acted goofy like this or do they just go out?
 
That is what seems to be going on. Later today I will do the timing light. I have checked coil and wires with oms meeter and checked out good.
What about Stator. Can they acted goofy like this or do they just go out?
 
Well I agree on better prop but even when I trim to high the prop blows out and engine still wont rev any more than 5100rpms. Just cant seem to get any high rpms. Just seems like im down one cylinder but yet motor starts n runs smooth and has no trouble getting up on plane but still no top end.
Any more suggestions?
 
Well I agree on better prop but even when I trim to high the prop blows out and engine still wont rev any more than 5100rpms. Just cant seem to get any high rpms. Just seems like im down one cylinder but yet motor starts n runs smooth and has no trouble getting up on plane but still no top end.
Any more suggestions?
 
Took boat out for test run today and still no rpms over 5000. I noticed that while watching tach at wot and trimed just rightthat rpms will surge about 100 to 200 rpms and you can feel the power surge. Going to check carb jets to see if cloged or varnished restriction. Jut seems like one cylinder is not running full power. Might be carb fuel problem. Will test on friday on lake.
 
The Quickstart system drops out when engine temp is 95+ degrees or when RPM is above 2000. It does not effect WOT timing so the sensor/switch is not your problem.
 
Has anyone worked on your flywheel and replaced the magnets. If so did they put them in right, meaning you have to put them all in with the beveled end up and to the right as you look at the flywheel bottom . If not you cancel out the electric charge to the power pack. My 3 and 4 cylinders were not firing on a Johnson 200 HP.

Removed the two that was up side down, glued them back and I had firing on 3 and 4 cylinder.
 
The boat ran fine last fall before I put it away. I foged engine and put new plugs in. I have been having problems since the first start up this year. It just has no highrpms. Max rpms is 5000 even if prop blows out. Last year At wot was 6000 - 6200RPMS. (yes prop is to small). SO I put the original plugs back in and still no change. Im lost.
 
You may have a corroded connection. I would take apart every connection that pertains to the firing of spark plugs and make sure they are making good contact. Use some 400 grade sand paper to clean the pins where necessary. I read about a individual that had a bad connection on the power pack and it solved his problem. Also make sure the ground wire on the power pack is making a good connection to the power head. don't just read with a ohm meter, take it off and inspect it.
 
Today i checked plugs and found one pulg black in color. This is the second time i found this on this cylinder. So i swaped the coil to a different cylinder. Will test run on tomarrow. I hope to find that the cylinder i switched it to will be black plug then i will replace that coil. If not and the same cylinder is black plug then will be buying a power pack. Would rather pay for a coil.
 
Like was said above the first step is to clean all connectors and grounds good. Spreay the connectors with electrical cleaner and sand the grounds metal to metal. That includes components that use the mount bolt for ground. It is part of preventive maintenance and should be done regularly. Do you have a volt meter? Keeping an eye on the charging system can prevent expensive repairs if you shut it down in time. Hopefully just swapping coils will cure the problem! Oh yea put dielectric on the connectors to protect from moisture.
 
Did clean all conectors today before taking it out for a run. After run i found the same cylinder has black and wet plug. I moved coil to different cylinder and ran again. Rechecked and same results. Wet plug and black. I ordered a new power pack. Compersion is between 105 to 114 on all cylinders.
 
Yes did onms test and many other tests of ingiction system and all cecked out ok. The one test I did was put a timing light on each one of cylinders and found that the same cylinder that plug is black and wet that the light flshing was inconsistent. All the other cylinders were in a rythem flashing. But one was not. I have watched fuel flow threw each carbs at WOT with cal off carbs. I know fuel is not the problem. Power pack is in shipping transit. Will up date as soon as I can install it and test on water.
 
Well no luck. I replaced power pack and test run last night and I did gain 200 more rpms but now I can here the engine trying to gain more. Its like its not getting enough fuel or spark in one cylinder. I did not replace spark plugs to the recumended plugs for the new power pack. I did take out each high jet and spray carb cleaner in each one to clean carbs with out taking carbs off. Jets and carbs look very clean. Fuel filter looks clear and clean. Buying new recumended spark plugs today and replacing them.
Is there anything else I can try before I take it to test on tuesday????? Ugggg so lost.
 
Are you sure the carbs open up exactly the same time and the throttle butterflys are fully open at WOT? The slow jets also supplement the upper end exactly how are you adjusting the slow jets? Have you tried turning all of them out 1/4 to 1/2 turn to see if top end improves? Running the slow needles rich will also improve cold starts and the hole shot.
 
Have you looked into crankcase compression issues ?-------The black plug may indicate a cylinder is running " cold " and not getting proper scavenging / fuel air charge.-------Which cylinder is the one with the black plug ?
 
2800 ft alt. The cylinder was the one on the bottom on the right looking at the plugs.
I just checked the plugs from running last night. Now all plugs seem to be firing. All plugs are a tint brown even the one that wasnt fireing before. The plugs in it now areChampion QL78YC
The new power pack recamends to use Champion QL77JC4. I am picking up the new plugs tonight.
 
You may need smaller high speed jets for better performance on the upper end. Call seawaymarine in lynnwood WA on tuesday and see what they recommend. Pull one of the high speed jets and see what size is stamped on it. Normally you want to go two sizes smaller for every 2500 ft elevation for the fuel jets. If you have the air bleed jets you want to increase the size depending on elevation.
http://www.seawaymarine.com/
They have the best books only open mon-fri monday being a holiday.
 
I`m seeing #72D for high speed and #30 for air bleed those are for sea level to 2500ft. If you rejet make sure to switch back if you run at lower elevations!
 
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