1993 Mariner 75 hp Carb idle setting - Which Way is Leaner?

[j_k_bisson]

I have a stupid question for everyone here. I have a 1993 Mariner 75 hp - three carb - motor. I have purchased a Factory service manual and have read all the sections of setting the idler jet screw. It states, initial setting 1.5 turns out, in water, in gear, warmed up, turn in each idler screw at idle until motor "Bogs or misfires", back out 1/4 Turn. Confirm with run. Do not run lean. Which way is leaner? In or out? I think in is richer, but nowhere in the factory service manual does it say..

Please confirm....

 

[Faztbullet]

This the mixture screw or the one under sealed cap???

 

[j_k_bisson]

no the one on top of the carp that the idle fuel mixture circuit is set by. Here;


The reason I am asking, I rebuilt the carbs over the winter, had it out yesterday and set as per the service manual, and it was like 2 turns out when set accordingly. But when coming off plane the motor would cough and die on occasion if let down too fast. Ran great at full and mid throttle. and Idle without kicking too much.

So this leads me to think that the idle circuit is too lean, but I don't know which way is leaner or richer.

 

[DeepCMark58A]

Righty tighty lefty loosey. Could be too rich as well.

 

[j_k_bisson]

Righty tighty lefty loosey. Could be too rich as well.

I know this, but if its an air screw, you get richer as the orifice gets smaller. If it is a Metering screw then the smaller the orifice, the less the fuel or leaner condition.

So my question is is this an air screw or a metering screw. I looked at the carb the way it was built and I think this is a Metering screw. But want to confirm.

 

[Faztbullet]

Ts a metering screw..in lean out rich

 

[j_k_bisson]

Ts a metering screw..in lean out rich

Thank you.

Another stupid question. I had reversed the enricher valve in and out. Would this have caused the issue of popping and dieing off plane? Sucking fuel thru the enricher valve?

 

[Faztbullet]

Nope..its just a valve ..always closed until key activation.

 

[j_k_bisson]

Nope..its just a valve ..always closed until key activation.

Didn't know if it was a spring operated solenoid. and when pressure was back feed, that the valve would open allowing fuel to flow. Thanks for the response.

Also here is more to what I have going on. I pull the plugs last night. These where new before going for an hour total run time, 1/2-5/8 hour at WTO, and 15-20 at idle. Could not get it way down to idle on way back to dock or it would die cough and die out.



Can you tel me which one is leaner and which one is rich. From Left to Right is Bottom to top.

 

[racerone]

The one on the right looks like it is not firing.-------Simple tests to do.-------Compression test and post your numbers.----See if spark will jump a gap of 3/8" ( 1 cm ) on all 3 leads.----Is oil injection in service , tested or bypassed ?-----Water pump serviced ?-----Did your problems show up suddenly ?

 

[j_k_bisson]

The one on the right looks like it is not firing.-------Simple tests to do.-------Compression test and post your numbers.----See if spark will jump a gap of 3/8" ( 1 cm ) on all 3 leads.----Is oil injection in service , tested or bypassed ?-----Water pump serviced ?-----Did your problems show up suddenly ?

Compression

125 PSI - Top
122.5 PSI - Mid
125 PSI - Bottom

All cylinders jump 7/16" Gap as per manual.
Carbs completely rebuilt, original jets, just new gaskets.
New water impeller kit
New Fuel Lines
New Plugs and gaped per factory service manual

One on right was wet. Other 2 where mildly wet with fuel, but have burn marks on them. I was thinking the from Right to left the mixture was richer, indicated by the dark marks....

Boat is a new acquisition to me. So not idea on the what was done prior to me other than the fuel pump being rebuilt 2 years ago.Seen dealer invoice for work and parts completed.

 

[racerone]

Take it back to the dealer I say.

 

[j_k_bisson]

Take it back to the dealer I say.

Bought it privetly and it ain't going back!