Now my 84 90hp won't Idle

[Kyle C]

Hey guys, my Johnson '84 90hp (j90tlcrd) won't idle unles I keep the choke pushed until it almost stalls and then let it go until it almost stalls and so on and so on. I'm thinking the fuel pumps not working but I thought I'd ask the experts.

 

[merlion497]

Re: Now my 84 90hp won't Idle

I am by no means an expert but ive had the exact same problem and here is what I did.
Your getting too much air is all, i'm pretty confident that your pump is fine.
Hopefully you have the service manual or know exactly what your doing, because the process should be as precise as the thickness of a piece of paper(literally), but what i did was completely re-sync'd the throttle cam. You could check to see if this is the problem by taking off the cover/air-filter of your carb and looking at the flaps. When your in idle ( you dont need to start your motor to do this btw) the flaps should be 100% closed. Then as soon as you start turning your throttle they should begin opening until, when fully throttled, the flaps lay horizontal.

Im guessing at full throttle, your flaps are going to be overly open. And when your in idle the flaps will not be completly closed.


While the syncing is pretty precise, it really is easy. Dont even need any special tools or anything. Also you will truly benefit from syncing the motor and watching the flaps as you do it. Understanding the concepts behind your motor will make troubleshooting your motor easy, especially when your out on the ocean and cant ask iboats
I found this other post that talks about syncing your throttle and has some more good imformation and explanations as to the actual concepts.
http://forums.iboats.com/showthread.php?t=249685

 

[merlion497]

Re: Now my 84 90hp won't Idle

Last quick note, i'm sure you know this but just to be safe, when your goofing around with your carb, keep it clean. dont prod the flaps with your fingers or anything sillykeep all the bolts and pieces in the carb cover that you removed etc. If you search iboats forum for carb stuff it will definatly give you alot more information.

 

[Kyle C]

Re: Now my 84 90hp won't Idle

Thanks Merlion, I just rebuilt the carbs, checked for spark (good) and checked compression (118-120) so I'm glad to hear that it might be something else. I have checked the butterflies to see that they move in unison but haven't checked the marks on the cam. I'm pretty sure the butterflies are completely closed but of course, once you second guess yourself, your not sure any more. I'll do that first thing tomorrow. I appreciate your help. I'll keep you posted.

 

[merlion497]

Re: Now my 84 90hp won't Idle

Thanks Merlion, I just rebuilt the carbs, checked for spark (good) and checked compression (118-120) so I'm glad to hear that it might be something else. I have checked the butterflies to see that they move in unison but haven't checked the marks on the cam. I'm pretty sure the butterflies are completely closed but of course, once you second guess yourself, your not sure any more. I'll do that first thing tomorrow. I appreciate your help. I'll keep you posted.

good luck, i hope it works. and sorry that my post is so dumbed down haha. You obviously didnt need me to tell you not to prod the butterflies hahaha. Better safe then sorry.

If that doesn't work, the only thing i can think of that you havent mentioned doing is the exact opposite, not enough air. Maybe you have an exhaust leak somewhere under the cowl. So when your moving, the air is cleared out, but when your stopped and in idle, the exhaust builds up blah blah. Easy test, try idling with the hood off.

 

[Kyle C]

Re: Now my 84 90hp won't Idle

Well, unfortunately, that didn't work, it still won't idle. It starts up strong every time but bogs down after a few seconds. Could it be the primer solenoid? I took one from an '81 90hp Evinrude. I checked and found that they were all superceded to the same number so I figured it would work.

 

[ezeke]

Re: Now my 84 90hp won't Idle

The primer solenoid is just a valve that lets you enrich the fuel/air mix by going around the carburetors.

When you can keep the engine running by using the primer solenoid it usually tells you that the carburetors are not working properly.

The fuel pump just fills the float bowls and provides pressure for the primer solenoid.

The fuel is pulled through the carburetors by vacuum created by the movement of the pistons.

If there is an air leak or restriction on the gasoline supply, the engine will run poorly or not at all.

 

[Kyle C]

Re: Now my 84 90hp won't Idle

Let's go back a little bit. I removed the lower unit and removed/replaced the transom mount/tilt trim assembly. While I had the motor apart, I painted it. After I put the motor back together it started to give me the trouble it's giving me now. It used to idle ok, it could of used some adjustment, but now, not at all. If there is anything that could have happened in the process to make this happen I would love to know about it, I can't think of anything though. Again, I thank everyone for their help.