Oil Injection removal

[gbrowne63]

i just removed the oil injection on a 1988 135HP. My question is what do i do to the carbs with a now richer mixture. I had a 1986 and it had idle air jets i made bigger so it pulled hard right off idle.

 

[Chris1956]

Why exactly is the mixture richer? You went from a 50::1 oil injection-created mix to a 50::1 premixed fuel.

 

[gbrowne63]

oil injection at idle is 100: 1

 

[Chris1956]

OK, Even if that is true, of which I am unsure, how long does it take when you first go to idle, before the mixture becomes 100::1? How long dies it take before the mixture becomes 50::1 as you throttle up slowly?

Your engine doesn't care a lot what the mixture is. You obviously need a 50::1 mix for high speed operation, but they run just fine on a 50::1 mix at idle as well.

 

[gbrowne63]

when I had my 1989 merc 115 2+2 and disconnected the oil injection I had to adjust the mixture screws so it would accelerate well, same thing on my 1986 135HP but I drilled out the idle air jets. I don,t see them on this carb arrangment.

 

[gbrowne63]

the oil pump is dirrectly connected to the thottle linkage so from 100:1 to 50:1 is a progressive thing.

 

[Texasmark]

I pulled the drive gear out of my oil pump on a 2002 90 hp Merc. Went to 50:1 pre mix. Only thing I saw/felt/had different was a light puff of smoke when doing the (start of the) hole shot coming out of the no wake zone that I didn't have before with the 90:1 my service manual said my engine ran at idle using the onboard, internal oil pump.

 

[Chris1956]

Gee, I don't think you should make any mods to the carb jets. If it runs poorly, clean the carbs and adjust the idle mixture, as you would on any motor.

I would guess that thousands of Mercs have been converted to premix. I understand that there are cover plates sold, to fill the hole where the oil pump sits. That means a common conversion, at least to me.

 

[gbrowne63]

I don,t think there are idle mixture screw on these carbs. If so where?

 

[gbrowne63]

I just watched a utube video on carb rebuilds and answered my own question,thanks for all the input. GORD

 

[Chris1956]

Some of the V6 engines had fixed low speed jets. That makes your question academic.