Help please 90hp johnson two stroke issues.

[Pink Shibi]

i have a 91 johnson 90hp two stroke that has been running fine until i caught a nice mahi mahi. then it seems as if i have offended some hawaiian deity. when i revved the boat back up after the fish it went fine till about 5-6 knots then it bogs down like it has no fuel or air. lower the rpms runs fine. if i pump the gas ball as i am running it will run fine. i looked at the fuel water seperator afterwards and it was full of water and dirt. i changed the fuel water seperator and ran it at idle 5 mins. turned it off and drained some of the fuel from it and a tiny amount of water. then i ran it around the bay for a bit pumping the ball to keep on plane. stopped checked it again just a little water and by little i mean maybe a drop or two. brought it home flushed it out and looked at the engine. noticed my service valve was cracked. so i replaced it. took it out on the water same problem. brought it back and was flushing it out. noticed that if i choked it it ran much better. so i was playing with that and the motor died. now it has issues idling at all. i am guessing that i need to drain the fuel tank and start over there and rebuild carbs, but before i do that i though i would see if anyone else has any ideas.

thank you for your help.

pink shibi

 

[SEABEE#2]

Re: Help please 90hp johnson two stroke issues.

Running at half choke in my experience has always been a carb issue. Sometimes you just need to take them apart and clean them really good, while other times you have to rebuild it completely.

 

[James R]

Re: Help please 90hp johnson two stroke issues.

There is no question. Your carbs need rebuilding and probably the fuel pump also. Don't ignore these items or you will burn up your motor.

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

ok did some more work to it. I am back to square one. i changed it over to run from a gas can and eliminated fuel system all together did not fix problem. so nothing from tank to engine. replaced fuel lines cause they were cruddy. took apart carbs and sprayed em out with carb cleaner in the needles and the float valves, even though they look fine no grine or salt deposits at all. the jets are huge and there is nothing in them. my dirtbike also a two stroke has tiny jets and i have redone the carb many times and it was way dirtier than this to cause the same issues also the idle needles would clog first anyway and thats not an issue. the pump had a badly seated metal plate. i reseated it and put it back together. it is not an electric pump it is a mechanical pump with two one way valves and a diaphragm that looks to work like the ball from the gas tank or a heart. i have a new theory. after a certain point of opening the throttle the carbs are fully open. then i would guess only the timing advance would move with further increase on throttle lever. this position is the same one i get to when the engine bogs. Is there a cable or bar that would advance timing that could have come loose? and where would it be. it has the optical ignition. I plan on replacing pumps and doing a carb kit still does anyone know a good place online to get those peices?

 

[emdsapmgr]

Re: Help please 90hp johnson two stroke issues.

You've done some good troubleshooting. Sounds as if you have weak/insufficient fuel delivery to the carbs. Your fuel system pumps enough for idle, but won't sustain at WOT. Perhaps a weak fuel pump. To test for a weak fuel pump, you've primed the fuel hose bulb and found the engine will run fine at WOT as long as you keep priming. This action forces extra fuel directly into the carb fuel bowls and over comes the weak fuel system delivery. At first, the pump will fill the fuel bowls and it may run fine, till the carbs drain the fuel and the pump can't keep up with delivering extra fuel. The engine will then slow down (bog,) then the bowls refill, then it will take off again-only to bog again. Not sure what you mean by "replacing pumps." That engine should have come with a single VRO (combination fuel/oil) pump. I'd work on this fuel issue first.

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

good catch. i meant pump not pumps. it was 11:30 and i had a bit to drink to console my wounded pride at not being able to fix this. I have found the fuel pump on crowley marines website and ordered it. it was 125$ with express shipping. cheaper than the estimate of replacing it from the shop which was over 500 but i think they were trying to replace the entire vro system. this is just the pump. So i will replace that and hope for the best.

back to my earlier question do you think it could be the timing not advancing after the carb valves are wide open? or does pumping the ball completely throw this problem into the fuel pumps territory. either way i am doing one step at a time then testing. haha i am at test ride 7 now

thanks

 

[BonairII]

Re: Help please 90hp johnson two stroke issues.

If carbs are clean and it doesn't seem to be a fuel issue....Make sure to also check that your timing linkage etc hasn't come apart/loose. If spark isn't advancing.....your motor will bog down and not accellerate.

 

[V153]

Re: Help please 90hp johnson two stroke issues.

Have you checked/cleaned the filter in the fuel pump?

Also, pull the drains from the carb bowls & flush some fresh gas through. (I do em 1 at a time and try to catch any crud that comes out in a coffee filter.)

 

[rpsloan]

Re: Help please 90hp johnson two stroke issues.

There is a post about a 50 hp that had a picture of disconnected linkage under the flywheel. Good place to start checking. Have you looked at the quick connects to assure no debris in them? I agree with the others that if it's not the fuel pump it's the timing advance. Have you done a spark test? There is a slim possibility you are running on 2 cylinders or have weak ignition components. Also a compression test would tell a lot too.

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

Thanks for the input i haven't received the pump yet so no work done yet. but i have looked at the filter going into the pump reservoir its clean, no discoloration or residue or particles. and i took all the carbs apart and inspected and sprayed jets and float valves. honestly carbs look fine. something could still be wrong but no sticky floats and no obstructions in jets. my next steps are to change fuel pump and see what that does then i will work on timing especially since i can pump the ball and go faster. hopefully i wont have to mess with the timing which i am not particularly familiar with on an outboard. motorcycles and old cars i can do. also i have no idea how you would adjust timing under load without being bent over a motor flying down the bay at WOT. that seems like a safely hazard.
the linkage i could fix most likely and btw your post has no link that i can see rpsloan i would love that info. if the pump doesnt work and timing doesnt work then i will compression test and spark test. but i dont have compression gauge or spark tester so that will be more $$ out of pocket. also i am about to be sent on a 1 month training and have zero time to work on it. i was hoping to get out and catch more tuna before that. especially since they are starting to come in on the north and west side of oahu.

 

[rpsloan]

Re: Help please 90hp johnson two stroke issues.

http://forums.iboats.com/johnson-evinrude-outboards/95-johnson-50hp-591641.html

 

[V153]

Re: Help please 90hp johnson two stroke issues.

i have no idea how you would adjust timing under load without being bent over a motor flying down the bay at WOT. that seems like a safely hazard

Ya, I always thought so too. But bleve it or not that is the recommended procedure. Make sure you wear short sleeves & a hair net ...

Me I just make i minor adjustments'n see what happens? Regardless I doubt what you're dealing with is a sudden instantaneous timing problem. Good luck!

 

[boobie]

Re: Help please 90hp johnson two stroke issues.

Check the top secret files at the begining of this forum. Joe Reeves has a good procedure for setting the wot timing staticly. By the way the recommended procedure is to have a test wheel on the mtr and have it in a test tank or backed into a lake to set the wot timing. This was from OMC.

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

ok so new development. i had already siphoned gas out from the tank to see what it was like and it didnt look bad, but i did it again at a buddies suggestion. i guess the first time i must not have gotten it all the way to the bottom. what i sucked out yesterday was mostly clear baely a shade of yellow. and it tasted less like gas and more like water the more i siphoned out, as i got a fair amount in my mouth. so now i have a 55 gallon drum with 35-45 gallons of crapppppppy gas. may have been my whole problem. the pump is arriving today and i will replace it anyway and take her out. cross your fingers. i have mine crossed

pink shibi

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.



since i got bored i made a poor mans fish finder last night as well. i plan on using it to look at my chum slick to see how it drifts and if any fish have come in without jumping in with goggles. easy project.

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

ok so good news. i tested it today. i put new gas in it. took it down to the bay. ran good. then i put the new pump on since i had it anyway. man she ran sweet.

bad news. i was rolling around full throttle cause it felt good and it started spitting smoke. i got it back and had it on the muffs and it blew a seal somewhere. it is now spitting lower gear lube out the exhaust. i went from real happy to real sad pretty quick. more work to be done.

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

 

[hsdtech]

Re: Help please 90hp johnson two stroke issues.

Man it looks like you have luck like me! I would buy a lower unit seal kit. It's not too bad of a job, BUT if you do it yourself make sure you have some help dropping and re-installing the lower unit. Not sure of your model motor but don't mess with the shift rod too much OR it might come out of position. IF that happens then your looking at having to pull the gearcase apart to reset the rod. A real pain!

 

[Pink Shibi]

Re: Help please 90hp johnson two stroke issues.

well i pulled the lower unit oil plug and drained some out from the bottom. its not milky at all. period. or low for that matter. which leads me to believe that with all my recent problems and sitting for a couple weeks it just was cruddy in there and running correctly for once just blew it all out and im just expecting the worst so i must have jumped to the wrong conclusion. so i filled it back up with lower unit oil and im taking it to the water again tomorrow with a can of this sea foam i keep hearing about.

 

[kjdunne]

Re: Help please 90hp johnson two stroke issues.

Are you sure that is gearcase oil? I assume you are running with the VRO pump, not premixing your gas and oil. I had an air leak in my fuel line ('97 90hp Johnson) and the oil side of the VRO pumped way too much oil as the fuel side of the pump wasn't getting enough gas. The motor still ran amazingly well considering the gas / oil mixture was way out of whack. My leak turned out to be a ripped o-ring in a push on connector at the tank. My prop had the same goop as in your picture. Thoroughly test your entire fuel line system leading to the pump for air leakage, air leaks don't always leak fuel out. An air leak could have been the cause of your fuel starvation issue from the start, or a bad fuel side of your VRO pump and maybe the replacement pump is bad also. If you are premixing and not using the oil side of the VRO, disregard all this.