90hp inline 6 issued at idle

[aarongreen123]

Motor starts hard, have to advance throttle in neutral almost all the time, then runs ok from there. After its real warm, if i throttle down to idle it will stall. Again i can get it started by advancing the throttle but have to be ready so it doesnt rev high in neutral. As soon as i put in gear it stalls out. Couple details. When i prime the bulb at first, the bulb gets firm, after about 90 seconds though gas starts to leak out Of the front of the top carb, like it is overflowing that brass tube. Had all new seals put in last year, not sureif that could effect this. I have carb kits to put on, gonna take a swing at it with the clymer this weekend. Motor runs great at high speed. Just looking for theories on what could be wrong, and what to look out for while i put kits in for the sake of further understanding of these motors. Thanks guys.

 

[dish]

Re: 90hp inline 6 issued at idle

Motor starts hard, have to advance throttle in neutral almost all the time, then runs ok from there. After its real warm, if i throttle down to idle it will stall. Again i can get it started by advancing the throttle but have to be ready so it doesnt rev high in neutral. As soon as i put in gear it stalls out. Couple details. When i prime the bulb at first, the bulb gets firm, after about 90 seconds though gas starts to leak out Of the front of the top carb, like it is overflowing that brass tube. Had all new seals put in last year, not sureif that could effect this. I have carb kits to put on, gonna take a swing at it with the clymer this weekend. Motor runs great at high speed. Just looking for theories on what could be wrong, and what to look out for while i put kits in for the sake of further understanding of these motors. Thanks guys.

Sound like carb float needs adjusting or might be stuck open and flooding the engine.It runs good at high speed because its using that extra fuel.Carb service time

 

[mercuk]

Re: 90hp inline 6 issued at idle

Sound like carb float needs adjusting or might be stuck open and flooding the engine.It runs good at high speed because its using that extra fuel.Carb service time

Couldn't agree more.....
Definately carb issues I would say. Once you have rebuilt carbs, lynk and sync engine and you'll be out and about in no time..

 

[Bob_VT]

Re: 90hp inline 6 issued at idle

Read this post which is a GREAT maintenance item for the inlines http://forums.iboats.com/showthread.php?t=168855

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

MAkes sense to me! Can anyone explain how to take the cArbs off in relation to the throttle linkage? Does that come off with them or do you take one carb off at a time? Coulndt really tell how that wants to be dismantled. I have that post bookmarked, i might need a little explain when the tome comes but i think i get most of it. Is it likely that the timing will need adjusting as part of this?

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

Have the first carb off, pretty sure the float adjustment was way off, doesnt seem like it could have seated the needle very well at all. Question, my manual says to remove the idle tube and plug, plug no problem, but the tub is flush with the bottom of the cavity it is in, how can that be removed? Clymer manual isnt that detailed, already can see the issues. A fuel strainer came in the carb kit, i dont see where there is one on theis bowl cover, side bowl carn model.

 

[Chris1956]

Re: 90hp inline 6 issued at idle

there are two different side bowl carbs used on inline 4/6 Mercs. The Banjo filters are for the earlier models, the ones with flat carb covers are back-drag carbs and have a small stainless screen under the brass t or elbow, instead of the banjo filters. Just blow out the idle restrictors. No need to remove them. Make sure to clean the idle passages in the carb throat. There are some small drilled holes that can get clogged.

Make sure to set float height properly. Invert the carb cover and set the secondary lever so it is parallel to the carb cover. Bend primary lever to achieve that. With the cover right side up make sure the distance between levers is 1/4". Bend secondary lever to achieve. Make sure float is not disolving, and spring is 3/32" long. Replace if in doubt.

 

[Chris1956]

Re: 90hp inline 6 issued at idle

One more thing. Make sure idle pickup timing is spot on, per Clams' procedure.

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

had the first carb apart last night and i definitly need to adjust that float as those measurments are whats there. couple things

having a hard time getting that elbow off the bowl cover to clean that screen, nothing to grab on the bowl cover side and don't want to break something, any ideas? shouldn't skip this should i?

needle showed a small amount of wear. i did notice a couple things about the seat. there didn't seem to be a gasket between the seat and the bowl cover, also didn't seem to be a washer under the seat. does look like there is a copper piece in the cavity where the seat screws it that fits it perfectly though. the manual shows a gasket, and the kit came with a small copper washer. i guess there could be an old one in that cavity that i am seeing and its stuck, but its not moving and i don't want to screw up those threads. thoughts?

what about that idle tube? didn't seem to be a way to get it out? hosed it down with lots of carb cleaner, there actually wasn't a lot of crap in this carb like i expected.

i ordered 1 replacement float with the three kits, it is different slightly than the ones that are in the carbs, is it a problem if 1 float is aftermarket and the rest are stock in the event that i find one that needs to be replaced? thanks for your help so far, cant' wait to get this wrapped up this weekend.

 

[Chris1956]

Re: 90hp inline 6 issued at idle

Ther should be a copper washer under the inlet needle seat. No other gasket. Blow thru the brass elbows and tees. If the are clear, no need to remove. Blast the idle restrictor tube to make sure it is clean. They are hard to unscrew after they get old. Make sure the main jet and main nozzle are clean. The main nozzle has lots of small holes around it's base, thta need to be clean. Mixing old and new floats is not an issue. The original floats were foam and tended to disolve. Newer ones are hard plastic. They can crack.

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

Thanks again. Its all back together and it actually runs;-). Not very well though as i havent had a chance to get it on the water to adjust carbs, on top of the fact i really dont know what i am doing;-). Is it likely that the top carb would need to be adjusted different, or all three different? The manual says start at 1 1/2 turns out, the instructions with the kit say 1/4 to 1/2. If u had to screw that up is it better to have it more turns than needed or less? I would yhink one is safer than the other.

 

[canoemang]

Re: 90hp inline 6 issued at idle

1 1/2 turns out and adjust from there.

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

Does it make sense to do any of the adjustment in the driveway with the muffs on or I do the whole thing on the water

 

[wired247]

Re: 90hp inline 6 issued at idle

You wont be able to tell anything without a load on the engine. Pretty much got to be in the water for any meaningful adjustments

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

Any chance it will run perfect just like that-) ha! It definitly runs better already, no as leakin. It still twitches here and there like its missing but i think it is set to idle too low. The tach isnt working yet so i will have to wing it a little. Should this thing run silky smooth or are they always a little rough at idle?

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

Got it out in the water today. Idles perfect in neutral, idle in gear is still a little low and rough, high speed is perfect. Much improved, i dont think its perfect but its so much better. Thanks a lo lt for your help with this!

 

[twebb]

Re: 90hp inline 6 issued at idle

got the same prob with my 1986 90hp inline. did you do a lynk and synk after rebuild on carbs?

 

[aarongreen123]

Re: 90hp inline 6 issued at idle

I did not do the link n sync yet. I need to get the carbs adjusted a little more. Took it out tonight and the idle in nuetral is far better, better but not perfect idleing in gear. High speed is good. Advancing the throttle from idle is a little rough up until about half, so i think the bottom two carbs might still be out of wack at idle stage so need to get back after it. How far through the throttle range does the idle mixture screw effect performance?

 

[Chris1956]

Re: 90hp inline 6 issued at idle

The mixture screw is out of the equation by about 1200 RPM or so, give or take....