NEED HELP johnson 1985 90 hp missing at idle

[taabalb]

I am stumped i have a 1985 johnson vro v4 90 hp. it idles great but misses when its in the water and you just putzing along you really notice it. but it runs like a raped ape at full throttle plenty of power. coils new, power supplies new ,carbs cleaned throughly, timing good, after running plugs are wet no dry. also if i spray choke cleaner around the base of either carb it trys to stall , also at the lower base of intake manifold. so i assumed that that since it was so close to the base that it was sucking it thru the crank seal. but whaen i took the power head off all i found is that the exhaust gasket was corrupted and had been leaking have new gasket set on the way with new crank seal. also motor starts great at the flick of the key and has 125 psi compression in all 4 cyl. vro is disconnected and plud the oil line. please help sorry so long any help would be great.

 

[emdsapmgr]

Re: NEED HELP johnson 1985 90 hp missing at idle

You could have a lean sneeze miss at idle. Sounds just like an ignition miss. When you cleaned the carbs, did you remove the idle jets and purge the passages? The passage is like a Y. It connects the idle jet to the carb bowl, via a brass tube and exits in a pinhole in the carb throat after the butterfly. This whole system needs to be clear. Four of them, one for each throat. A good aerosol carb cleaner should help you determine if the system in functional.

 

[taabalb]

Re: NEED HELP johnson 1985 90 hp missing at idle

yes i cleaned all the passages with a small wire. and choke cleaner.

 

[taabalb]

Re: NEED HELP johnson 1985 90 hp missing at idle

cleaned the carbs again checked floats all good same problem , but should the plugs be wet after running , not soaking but some fuel is on them ,

 

[ezeke]

Re: NEED HELP johnson 1985 90 hp missing at idle

There should be fuel/oil mix in the firing chambers, on the pistons and rings, on the bearings, etc. It is practically impossible to have that and not have some residual oil on the spark plugs. I would be concerned if one of my plugs were dry.

Do you have plastic float bowls on your carburetors?

 

[taabalb]

Re: NEED HELP johnson 1985 90 hp missing at idle

no they are aluminum. i checked them with a straight edge also to make sure they arent warped. is it normal to be able to spray choke cleaner around the base of the motor and bog it down. almost where the case meets the extentison for the lower unit i put a new gasket and it still does the same thing.

 

[taabalb]

Re: NEED HELP johnson 1985 90 hp missing at idle

anyone any more ideas

 

[ezeke]

Re: NEED HELP johnson 1985 90 hp missing at idle

Since the air intake is right next to the carburetor on your motor, I'm not sure what else you were expecting to happen when you sprayed there.-?


Did you spray through the carburetor idle capillaries and observe a good flow behind the throttle plates? Did you put new gaskets between the carburetors and the intake manifold?

Did you service the recirculation check valves while you had the carburetors off?

 

[taabalb]

Re: NEED HELP johnson 1985 90 hp missing at idle

yes i did all that you stated, im not talking about spraying at the air intake of the carbs im talking about the base off the power head. down by the shift linkage for the lower unit. that you can barley see . it acts as if there is a crack some where but i cant find it. i even took the power head off. to look. i have a 48 hp that doesnt do it if sprayed in the same spot. but the 90 hp has a little differnet configurations at the base . i am a ase certified mechanic of 22 yrs and this has me completly stumped. makes no sense. i have another set off carbs coming from 115 hp. im going to try those. and im going to re gasket the whole motor. if that works ill let you kmow thanks. also can you tell me where i can get an oem type manual for this 1985 90 hp vro v4 johnson. mine is a general and cover like 12 different engines. thanks

 

[ezeke]

Re: NEED HELP johnson 1985 90 hp missing at idle

The raised cover on the floor of the lower cowl is the air intake cover.

Now, if you have exhaust leaking around there you will run rough for sure.