2.5 V6 Mariner woes...

[snal]

Specifics:
1997 140 HP Jet Drive
New to me, it idled fine on initial test but poured fuel fro the lower carb.
Removed oil injection system.
Now 50:1 mix in fuel tank.
Cleaned all carbs thoroughly, and replaced gaskets an all 3 needles, float levels verified. (this cured the pouring fuel problem).
First on the water test was Friday morning...took several tries to get it started with choke, but finally did and idle was a bit rough but ok.
WOT was 4100rpm and approx 30-35mph.
Fiddled with the linkage to make sure that the butterflies were opening all the way, and verified that the cable adjustment was allowing the linkage to reach the pre-set "stop".
Tried to fire it back up (several hours later) and it won't idle without choke, 1500 rpm sounds like it's not firing on all cylinders, smooths out at 2000-4100 with same previous speed and WOT rpm (4100) but will dies below 100 rpm.
Have fire at all 6 plugs.
Idle mixture screws were carefully re-set to original setting (10.5 turns IN).
Throttle linkage settings unmolested.
What do I try next to get it to idle?...I plan to use a home made manometer to tune the carbs, but must get it to idle on it's own first.

 

[Faztbullet]

Re: 2.5 V6 Mariner woes...

Your about 1300 rpms shy of operatiing range. Did you change spark plugs as bottom one could be fouled from flooding? Are you sure on the settings of idle mixture screw as 10.5 turns in sue sounds like a like, its usually 2-3/4 to 3-1/2 turn out from a light seat.

 

[snal]

Re: 2.5 V6 Mariner woes...

Your about 1300 rpms shy of operatiing range. Did you change spark plugs as bottom one could be fouled from flooding? Are you sure on the settings of idle mixture screw as 10.5 turns in sue sounds like a like, its usually 2-3/4 to 3-1/2 turn out from a light seat.

Well, I finally found a list of spec tables in the manual. "Initial setting for idle adjustment screws is 1.5 turns out"...so I gently seated them, set them at 1.5 out (they were all at least 3/4 turn out too far)...fired it up...still a bit rough but it idled without choke. Let it warm up a bit, did 1/8th turn adjustments, then re-set the main idle adjustment at the linkage. She idles fine now, fires right up! Now I need patience for the next available on the water test!

Ooops!...Yes, I changed the spark plugs this morning. Originals were identical on each side...bottom-nice tan like they should be...middle-appeared fouled, much darker...top- both were like new, no signs of heat (which is why my first guess was no fire on the top 2).

 

[snal]

Re: 2.5 V6 Mariner woes...

P.S. this IS a factory jet drive...so I don't have the option of trying different pitch/diameter props. Trimming the unit made no difference in RPMs...didn't think it would.

 

[j_martin]

Re: 2.5 V6 Mariner woes...

Carbs all start at full closed, and operate in tandem. Link and sync procedure in the maintenance manual will get all your initial adjustments, including throttle pickup timing to spec. If you've turned any screws on the linkage, that would be your next step, or anything else you do is a crap shoot, with a possible outcome of grenading the powerhead.

hope it helps
John

 

[snal]

Re: 2.5 V6 Mariner woes...

Carbs all start at full closed, and operate in tandem. Link and sync procedure in the maintenance manual will get all your initial adjustments, including throttle pickup timing to spec. If you've turned any screws on the linkage, that would be your next step, or anything else you do is a crap shoot, with a possible outcome of grenading the powerhead.

hope it helps
John

Thanks John!
So far, the only thing I've altered on the linkage is the idle throttle stop.