# 90 hp johnson



## whodat

greetings
a 1990 johnson outboard, little hrs on it, automatic oil injector, fresh gas, fresh plugs, [they always look wet]
crumby idle and hard starting,,,,wide open - its ok
even the power trim causes the engine to almost quit
i am wondering if its a bad power pac
good day


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## Volt-Schwibe

i'm wondering, is the air filter clogged?

as the air filter clogs up it causes a "choked" condition, and the engine will run excessively rich.

to test, you simply run it for a moment with no filter, and then see if it runs leaner, or if the plugs are still wet.

the great part about these engines, is that they are relatively simple, with few parts.


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## whodat

thanks walt
its my friends motor, he is usually pretty good with them but you know, that just might have been overlooked.
when he gets home from work i will pass it along.


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## Red neck Nerd

is it using a magneto? (magnet on the flywheel with pickup really close to the flywheel) if so check the distance between the pickup and the flywheel saying that the airfilter doesn't fix the problem. also if neither of those help/fix the problem look into the timing key. it should be in a slot on the flywheel. if the engine has been stored all winter with out additives it may have some buildup in the lines.


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## whodat

hi, he said he ran it without the air filter, same deal, he had stabilizer in the gas over the winter, could be timing.....


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## johnwill

Could the carb have gotten gummed up by leaving gas in over the winter?


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## whodat

i wouldnt be surprised john, i am not a big fan of the gas stabilizer route..he is going to take it to a marine mechanic....$$$$$$


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## StaticInMyHead

It's important to _always_ run the engine dry before storing marine equipment for a long period of time. Even if it is just a week or so, run the engine dry; there can be no buildup in fuel lines if this is done. 
I'd take a better look at the air delivery, like WaltSide said. It may not be the air filter that is clogged, but the timing could be off so enough air doesn't reach the cylinder before the valve closes. It's simple to tune if you know what to do. Good luck.


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## whodat

hey
he has a 20 gallon tank built in, its kind of hard to run it dry at times. the 6 gallon portables were nice.
he ran it .. fresh gas,, he says it gets throttled up nice, nice rpms...but crappy idle and hard starting....plus the plugs are wet after a run, and he also says the gas consumpsion he feels is up.
so the timing seems to be a possibility.
i guess its a 4cyl with oil injection and i was wondering if the oil injector system is wacky. or if the gas line to the tank is compromised, but then would it have the rpms on full go?
have a good weekend
[mets won again} :sayyes:


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## matty

*90 HP Johnson - question*

He doesn't need to run the tank dry, just disconnect the gas line and run the engine dry. That will protect from the expensive problems that can come up due to gas/oil residue.

I have a question. I have the same motor. I didn't have a bit of trouble with it for 12+ years, then, bang! The last 4 trips out have been nightmares. First the o-ring around my gas cap cracked and rain got in my tank... rebuilt the carbs. Then one of the carbs got a piece of "something" in a jet. Rebuilt that carb. This last time, it started great, but when I put it under load, the motor bogged down like it did when there was water in the gas. I thought my head was going to explode... I started pushing in on the electronic choke and it "came out of the bog down". If I kept pumping the choke (pushing the key in) it would start to plane and the rpms would come up... Eventually, I no longer needed to choke it and by the time I put it back on the trailer, it seemed to be running well.

So my questions are 1) Can it hurt the electronic choke to pump it like that? 2) Anyone know/recognize these symptoms? 3) should I expect that what ever it was causing the motor to bog down when I gave it the gas is now gone?

This was the first time I've "planed out" since the carb re-build... Once it started running well it ran as well as it ever has...

Any light ya'll can shed on this is greatly appreciated.

Thanks!


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## BloodyKnuckles

*90 Johnson Question*

A bit of mis-information being dispensed here. A 90 Johnson does not have an air filter since there isn't a great deal of dust to deal with on the water. It does have an air silencer that bugs and mud daubers like to plug up. Second, it is not recommended that any two stroke engine be "run dry". No fuel means no lubrication. Just before running dry, the engine also runs lean which increases combustion temps which is also not good. Best treatment for layup is to treat the fuel with Stabil or other similar products. During normal operation, adding SeaFoam or like products help keep fuel systems clean. Gum and varnish clogs carbs which is likely what the problem is with this engine. If the carbs have not been cleaned and rebuilt lately, they are long overdue. Remove, disassemble, soak in carb cleaner, blow out all passages with compressed air, and reassemble with new kits. Never use old parts or you will get to do it all over again. When assembled, perform a link&sync and adjust idle quality in the water. There is no back pressure when using muffs so idle mixture and speed cannot be properly set unless the engine is in the water. Lastly - an engine specific service manual is a must for the do-it-yourselfer.


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## gofishchobee

hi to all,

recently restarted boat after a couple of monthes of sitting due to electrical probs, completed repairs and ran engine in yard for about 15 mins. with no problem. Refired boat next day before launching and started right up. after launching reversed off of trailer and tryed going forward enging bogged and died, restarted fine but, would bogg and die at idle to the point of no refire. carbs were rebuilt about 1 year ago. not sure but think maybe water in gas from recently adding 10 gallons to an empty tank. added fuel dry to tank. however, is there an easy way to rid of water from carbs without another rebuild?


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## k2skier

*Re: 90 Johnson Question*



BloodyKnuckles said:


> A bit of mis-information being dispensed here. A 90 Johnson does not have an air filter since there isn't a great deal of dust to deal with on the water. It does have an air silencer that bugs and mud daubers like to plug up. Second, it is not recommended that any two stroke engine be "run dry". No fuel means no lubrication. Just before running dry, the engine also runs lean which increases combustion temps which is also not good. Best treatment for layup is to treat the fuel with Stabil or other similar products. During normal operation, adding SeaFoam or like products help keep fuel systems clean. Gum and varnish clogs carbs which is likely what the problem is with this engine. If the carbs have not been cleaned and rebuilt lately, they are long overdue. Remove, disassemble, soak in carb cleaner, blow out all passages with compressed air, and reassemble with new kits. Never use old parts or you will get to do it all over again. When assembled, perform a link&sync and adjust idle quality in the water. There is no back pressure when using muffs so idle mixture and speed cannot be properly set unless the engine is in the water. Lastly - an engine specific service manual is a must for the do-it-yourselfer.


Does it have Optical ignition? There were a lot of idling problems with Optical ignition (it might be too old for optical). If you had a bad SCR (silicone controlled rectifier) in one power pack it could easily misfire at low revs. CDI ignitions are RPM dependent for the amount of voltage they produce. Timing should not be an issue with an idling problem, it is most likely carbs though. One very important piece of information is; DO NOT BOIL THE CARBS ANY LONGER than 20-30 minutes. OMC, Johnson/Evinrude (Bombardier) carbs have a coating that will be removed from too long of a dip, and may ruin the carbs. My tip is (and it's what I've been doing in my shop for 25+ years) is not to boil/dip the carbs unless they are badly varnished, and use a spray cleaner and or cleaning solvent to kit them up.

Check compression and spark first, you should have 125-155 for a strong engine. And the spark must jump a minimum of a 3/8" open air gap to be called good spark, not a 0.040 plug gap, that's not a true test.

Good tip on the in water test final adjustment, V4 OMC's are the worst for behaving differently with back pressure than any other brand or engine design I've ever worked on .

PS;
There is no harm in IDLING a 2 stroke out of gas.


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## k2skier

*Re: 90 Johnson Question*



k2skier said:


> Does it have Optical ignition? There were a lot of idling problems with Optical ignition (it might be too old for optical). If you had a bad SCR (silicone controlled rectifier) in one power pack it could easily misfire at low revs. CDI ignitions are RPM dependent for the amount of voltage they produce. Timing should not be an issue with an idling problem, it is most likely carbs though. One very important piece of information is; DO NOT BOIL THE CARBS ANY LONGER than 20-30 minutes. OMC, Johnson/Evinrude (Bombardier) carbs have a coating that will be removed from too long of a dip, and may ruin the carbs. My tip is (and it's what I've been doing in my shop for 25+ years) is not to boil/dip the carbs unless they are badly varnished, and use a spray cleaner and or cleaning solvent to kit them up.
> 
> Check compression and spark first, you should have 125-155 for a strong engine. And the spark must jump a minimum of a 3/8" open air gap to be called good spark, not a 0.040 plug gap, that's not a true test.
> 
> Good tip on the in water test final adjustment, V4 OMC's are the worst for behaving differently with back pressure than any other brand or engine design I've ever worked on .
> 
> PS;
> There is no harm in IDLING a 2 stroke out of gas.


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## gberch

I had an 88hp that did the same thing ---it was sucking air where it connected to the motor --mine had also been hard to start ---hope this helps


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## K-B

Year old thread


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