Like a thousand others...

[msmclean]

...my 1994 Evinrude 120 hp will not idle under load(in the water & in gear). It coughs and dies like it is starving for fuel. At mid & full thottle, it is fine and runs good. To date I have done the following:

1) Pulled the inboard tank, flushed and checked the conections for leaks ...none found. I had to do this anyway as I replaced a bad spot in the floor under the center console.

2) Pulled all four carbs, cleaned and placed back on the motor. No change...still idles rough on the muffs.

3) Pulled carbs again,recleaned and replaced floats,seats and gaskets according to tashadaddys carb cleaning instructions. I have not put the carbs back on and tried to restart.

4) I used a timing light to check timing and the spark is good.

At this point, after reading posts on this forum and the Seloc manual...I am led to believe I have either a leaking intake manifold gasket or a broken/stuck reed valve. Am I on the right track and do you have any suggestions about pulling the intake and replacing the gasket ? Can I determine the intake manifold is leaking by looking at the gasket ? Thanks in advance. Great forum by the way !

 

[karlow1]

Re: Like a thousand others...

Check the compression.

 

[iwombat]

Re: Like a thousand others...

I agree - check compression first. If that ends up ok, you can check the manifold by spraying some premix around it while running. If it perks up, then you have a leak.

Maybe you can describe how you cleaned the carbs. Did you remove all the jets and clean behind them? Did you remove the core plug and clean the idle capilaries?

 

[tashasdaddy]

Re: Like a thousand others...

have you blown thru the carbs, to make sure that the floats are working properly. i have found this is a fantastic method. you also have to get your link n sinc, and idle speed adjusted correctly. you can get idle close on muffs, but it has to idle higher than you want on muffs, as there is not back pressure on the exhaust. the final idle speed adjustment must be done in the water with the motor in gear.

 

[ezeke]

Re: Like a thousand others...

Timing and idle issues can be a challenge with your QuikStart ignition system, so be sure that you are using the model specific service manual for your engine.

 

[msmclean]

Re: Like a thousand others...

Check the compression.

Compression checked as follows:
#1- 140
#2 - 145
#3 - 140
#4 - 135

Thanks for your help.

 

[msmclean]

Re: Like a thousand others...

I agree - check compression first. If that ends up ok, you can check the manifold by spraying some premix around it while running. If it perks up, then you have a leak.

Maybe you can describe how you cleaned the carbs. Did you remove all the jets and clean behind them? Did you remove the core plug and clean the idle capilaries?

Carbs were disassembled and the idle and mid range jets were cleaned with a couple of small wires and carb cleaner. They were not removed from the carb. New floats, seats and gaskets were installed. Cover plates were removed and capillaries blown out with carb spray and compressed air @ 30psi.

I sprayed some carb cleaner(bad idea...i know) around the intake gasket to see if it changed the idle speed but did not appear to affect it.

Thanks for the help.

 

[msmclean]

Re: Like a thousand others...

have you blown thru the carbs, to make sure that the floats are working properly. i have found this is a fantastic method. you also have to get your link n sinc, and idle speed adjusted correctly. you can get idle close on muffs, but it has to idle higher than you want on muffs, as there is not back pressure on the exhaust. the final idle speed adjustment must be done in the water with the motor in gear.

Carbs were blown through then inverted and blown through again to ensure needles were seated and allowed no air through. When I get it idling correctly, I will take your advice and adjust on the water in gear. Thank you !

 

[msmclean]

Re: Like a thousand others...

Timing and idle issues can be a challenge with your QuikStart ignition system, so be sure that you are using the model specific service manual for your engine.

Seloc Johnston/Evinrude 1992-01 Repair Manual. It seems to cover most things but failed to make mention of the fact the small plastic washer should NOT be used under the new needle seat on the plastic carb bodies. Thanks.

 

[tashasdaddy]

Re: Like a thousand others...

"Carbs were disassembled and the idle and mid range jets were cleaned with a couple of small wires and carb cleaner. They were not removed from the carb."

doing a job 1/2 way gets 1/2 way results.

 

[rebars1]

Re: Like a thousand others...

Definitely set the idle with the boat in the water. It takes two people, one driving, one adjusting.

When I first got my boat I re-set the idle while running on muffs. When I put it in the water, it would not stay running, so I re-set it tied to the dock. However, when I put it in gear, it died again, so I had to set it again! Now, on muffs, it runs fast (1300 rpm) but in the water it is just right.

 

[msmclean]

Re: Like a thousand others...

Update:

I pulled the intake today and found the intake gasket was 3/4 satuated with gas. I reassembled with a fresh intake gasket and the boat will stay running at idle and is much smoother. I have not tried it in the water yet.

Question: I was forced to re-use the old paper gasket between the throttle plate and intake manifold. I was told when I ordered the gaskets that the throttle plate & intake manifold could be removed as a single assembly. It could not...and I had to take the throttle plates off to get to the intake manifold bolts. Should I order & install a new gasket between the throttle plates and the intake ?

 

[kandil]

Re: Like a thousand others...

if it is not leaking it is OK you should try some sea foam treatment it will free your rings and restore compression and clean the powerhead.

 

[msmclean]

Re: Like a thousand others...

"Carbs were disassembled and the idle and mid range jets were cleaned with a couple of small wires and carb cleaner. They were not removed from the carb."

doing a job 1/2 way gets 1/2 way results.

No disrespect intended here but my initial post clearly indicates the carbs were rebuilt according to your instructions. Does this response indicate the instructions were "doing the job 1/2 way" ?

 

[tashasdaddy]

Re: Like a thousand others...

Your statement "Carbs were disassembled and the idle and mid range jets were cleaned with a couple of small wires and carb cleaner. They were not removed from the carb." this is what is was refering to. "They were not removed from the carb"