1985 Johnson 175 Lean Idle Hiccup

[Mugsey]

I've got a 1985 Johnson 175 with type III carbs and I'm experiencing a low speed hiccup. I've deduced from searching the forum its a lean idle problem. I understand I need to adjust the low speed orifice and make it richer but where is it and much of an adjustment? On the type II carbs it was above the carb bowl drain screw but not on these type III's. As always thanks for your time and advice in advance!

 

[Dhadley]

Re: 1985 Johnson 175 Lean Idle Hiccup

What's a type II and III OMC crossflow carb?

 

[Mugsey]

Re: 1985 Johnson 175 Lean Idle Hiccup

Type II pre vro (omc) Type III vro (omc)

 

[Gary H NC]

Re: 1985 Johnson 175 Lean Idle Hiccup

On my 81 there is no adjustments.You have to go down in size of the idle air jets.

 

[Dhadley]

Re: 1985 Johnson 175 Lean Idle Hiccup

What does the carb have to do with using a VRO or not?

 

[Mugsey]

Re: 1985 Johnson 175 Lean Idle Hiccup

Type II omc carbs used a choke solenoid, type III omc carbs used a primer solenoid which injected fuel into the manifold and a vro pump to mix the fuel. Two totally different types of carbs, I was only using the older type II carbs as a reference because the low speed adjustments were easy to find. The vro type III carbs either dont have low speed adjustment or they're set using another method. Sorry this has become an issue. Gary H NC answered my question I believe. There are none evidently. I'll have to go down a size in my idle air jets to fix the hiccup which was my original issue.

 

[Dhadley]

Re: 1985 Johnson 175 Lean Idle Hiccup

Just never heard of them refered to like that before. Yes, the carbs for that year motor had all fixed jets. Usually a lean sneeze on V6 crossflows is a linkage adjustment issue rather than a jetting issue. Assuming the carbs are clean and have all stock jets in the right places.

 

[Mugsey]

Re: 1985 Johnson 175 Lean Idle Hiccup

Carbs are newly rebuilt and extremely clean with the floats adjusted just about perfectly, I'll do a linkage sync and see if that fixes the issue. If its not a linkage issue would a larger jet give me a smoother idle? It has jets with the number 33 on them.

 

[emdsapmgr]

Re: 1985 Johnson 175 Lean Idle Hiccup

When you do your sync and link, make sure all 3 carb butterflies are closed at idle. If one is slightly cracked open, it will cause idle problems, as Hadley said.

 

[Gary H NC]

Re: 1985 Johnson 175 Lean Idle Hiccup

One of the guys here gave me a tip on checking the idle air jets.
With it running carefully use a toothpick and plug each air jet to see if the hiccup goes away.That way you can tell if just one carb is running lean or all of them.
Be careful to not let the toothpick get sucked in.At idle the butterflies should be closed so thats not really an issue.
The smaller the air jet the richer it will run.
I chased the same problem on mine.Carb rebuilds did not help.
I rebuilt the fuel pumps and replaced every gasket on the air box and carbs and it got better.
Still not sure what the real cause was.It now just does it a little when cold but goes away.

 

[Mugsey]

Re: 1985 Johnson 175 Lean Idle Hiccup

Sounds easy enough I'll give it a try. Thanks!