1988 30HP Johnson start/idle problems

[fishtex]

For starters, I am not very outboard motor smart. I know enough to be dangerous and fool myself into thinking I know more...

History: Boat sat up for a couple of years and decided to bring it back to life for a coastal trip and hopefully some hunting trips. I pulled the carb off and separated the float bowl from the top of the carb. I sprayed heavily with OMC carb cleaner and blew out the high speed jet well. When I sprayed cleaner into the large jet it appeared to flow out of the float valve well. I did not dissasemble the float or needle valve assembly. I also could not seem to get a good spray through the tiny jet that is at the top of the carb.

I replaced the impellar, plugs, pump ball & hose, fuel tank, and the lower unit lube.

The motor fired up after about 8 pulls but would not hold an idle. If I keep some pressure on the throttle it will stay running but as soon as I let go of throttle the engine dies. Then it is really difficult to get it started again.

I thought it just needed to be run so I took it to the lake today and got it fired up with the cowling off so I could reach the throttle and keep it running. Once it was in gear and throttled it ran like a champ. It gets on plane just fine and runs at lower speeds and high speed (high for a 30HP). As soon as I got off the throttle and it wound down it stalled. I could not get it to start for some time but when I did finally get it started I had to quickly get it into gear and moving so I could get back to the ramp. Again, as soon as I let go of the throttle and the motor wound down to idle RPM it died. I was unable to get it started again so I put it on the trailer and came home.

So... based on what I have read on this forum so far it would appear that either my idle jet is clogged or my float valve is sticking. But I wanted to get some opinions with the specific info for this motor. The problem really seems to be isolated to starting once warm and idling.

Some additional observations:
When I attempted to spray cleaner through the small jet on top of the carb I could not get a flow.

The throttle will turn a 1/4 inch or so and not actually move the throttle arm on the carb.

The needle valve turns with little to no resistance.

The choke (primer) will not stay out and sucks back in almost all the way like it has a vaccum on it.

I need this boat next monday and since I was able to crank it I thought I was out of the woods. I am getting nervous that I won't have it running properly in time. I need to get parts ordered ASAP and overnighted if I am going to spend any time working on it this weekend.

Any help ya'll can provide would be greatly appreciated.

Mike

 

[jonesg]

Re: 1988 30HP Johnson start/idle problems

Order a carb rebuild kit and get the idle jets open with thin strand wire, replace the seals and float needle/seat.

The throttle timing is supposed to move before the carb starts opening, it has to advance and it controls idle speed.

But no idle is a clogged carb more than likely.

You might be missing something from the choke mechanism, maybe a spring, check down in the engine pan that you didn't drop something.

 

[fishtex]

Re: 1988 30HP Johnson start/idle problems

Thanks jonesg... I will be ordering the carb kit shortly if I cannot find one local.

Do you think this is the same cause for the difficulty in starting the motor once it warms up?

 

[robeward]

Re: 1988 30HP Johnson start/idle problems

You are describing how my engine performed exactly. Rough start/no idle even after warm up. My biggest problem was my timing was off. Had a mechanic fix it so not sure how bad or what was involved. Follow jonesg advice. Just be confident in the carb cleaning so you can move to other causes if that doesn't fix it. Make the special jet tool from the sticky while you are waiting for your kit to arrive. Good Luck!

 

[fishtex]

Re: 1988 30HP Johnson start/idle problems

I got some time to work on the motor this evening and the end result is SUCCESS......

There was definately a clog in the small jet on the top of the carb and I was able to get that cleaned out by gently working a sewing needle to break up the debris and spray it out with carb cleaner.

The idle needle that turned so freely was also part of the problem. The gasket the needle goes through was broken in half so I replaced it as well after spraying some cleaner throughout that area.

I dissasembled the float assembly and it looked to be in good shape so I did not replace it, just sprayed some cleaner throughout.

I replaced the gaskets during reassembly and she fired up with about 3 cranks. I was able to reduce the throttle down to a high idle and it stayed running. I was able to adjust the idle needle and get the throttle almost all the way turned down without the motor stalling.

I ran the motor for a little while on the ear muffs and killed it with the kill switch. One pull of the cord and it fired right back up and idled fine. Went through this a few times and it cranked on the first pull each time.

I hope there is nothing else I need to take care of on the motor before hitting the water because it is going to get some run time next week.

I have replaced the plugs and impeller, drained and refilled the lower unit fluid, carb is taken care of, replaced the pump ball and line, got a new fuel tank, put a new axle under the trailer with new springs, new hubs, and new tires. The transome will need to be replaced but not before this trip.

Thanks for the tips guys, with what you provided I was able to get this motor running better than I remember it running years ago. Hopefully the depth finder still works... I have short list of things remaining to complete but they are not things that would prevent me from taking the boat out.

Thanks again and hopefully what worked for me will help someone else solve their motor problems.

 

[robeward]

Re: 1988 30HP Johnson start/idle problems

Nice job fishtex. Good to see you got her going. Seems to be another good example of how junk in the carbs affects engine performance. Now load the boat with fish.

 

[northwoodslivin]

Re: 1988 30HP Johnson start/idle problems

Good job

One word of advice though "I basically have the same motor as you 1989 20HP" replace your original fuel lines!!! I had a heck of a time with my motor "cleaned the carb 4 times" what happens is that the old Johnson l lines are not rated for ethanol gas and they get eaten up inside "while looking completely fine on the outside"

They now make new fuel lines rated for ethanol. Solved my proplem. Also, did you pull out the two core plugs on your carb and clean in there as well?
Happy boating

 

[jonesg]

Re: 1988 30HP Johnson start/idle problems

Good job

One word of advice though "I basically have the same motor as you 1989 20HP" replace your original fuel lines!!! I had a heck of a time with my motor "cleaned the carb 4 times" what happens is that the old Johnson l lines are not rated for ethanol gas and they get eaten up inside "while looking completely fine on the outside"

They now make new fuel lines rated for ethanol. Solved my proplem. Also, did you pull out the two core plugs on your carb and clean in there as well?
Happy boating

good advise there.

 

[jonesg]

Re: 1988 30HP Johnson start/idle problems

I got some time to work on the motor this evening and the end result is SUCCESS......

There was definately a clog in the small jet on the top of the carb and I was able to get that cleaned out by gently working a sewing needle to break up the debris and spray it out with carb cleaner.

.

Thanks for posting back, thats what makes this thing work.