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Killer

Low (rough) idle in gear?

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Killer

I have a low or rough idle when in forward (possibly reverse as well) idle. it jumps from 500-550 or so, but it keeps running and wont die at its lowest forward idle setting when warm.

the boat is new to me and I'm waiting on a service manual, so I dont want to screw anything up...

I'm thinking of just bumping the idle up a tad, but I have no idea what the RPM is supposed to be in neutral or idle? also not sure how to adjust on this motor, I'm used to a 351 w/4160 4bbl holley & not sure what carb comes on the 350ci 310hp indmar?

its a 99 sporty with the 310hp carb 350ci motor 200hrs.

I was told it could be the old gas in the tank. any and all suggestions appreciated. Thumbup.gif

thanks!

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99response

Idle in gear should be around 650.

-Chris

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Killer

hey thanks for the quick reply!

do you think I should just bump the idle speed up to 650? what should it be in neutral?

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99response

I think my 00 RLX w/ the 310 idled around 700 maybe a tad more in neutal and then dropped to around 650 in gear. I would go ahead and bump it up.

-Chris

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M3Fan

You can bump it up, and if it's still rough you can play with the idle mixture screws to smooth it out. There is a pretty straightforward procedure for adjusting the idle mixture screws, and it's probably documented here somewhere.

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88Skier

Could need a tune up too. Mine had developed a rough idle over time and replacing the plugs, cap and rotar made it idle like it's got efi. Mine idles aroung 800+-.

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Killer

thanks crew!

it has new plugs and wires last year or the year before (only 11 hrs on it last season 201 total). its never had a cap or rotor... so that is on the list for sure.

in the manual it states "tune up" every season - what is a "tune up" on these motors? I've done full electronic swaps and points gap adjustments on my 351 so I am good with motors, just don't have the experience with this type.

what kind of distributor and where should I buy the parts? I've used DIM for my 351, but they dont seem to have many 350 indmar parts or malibu for that matter...

sorry, but I'm a 'bu and chev/indmar newbie :)

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99response

Ski DIM has all the indmar stuff you need.

With a carby I would call a tune up, fuel filter, plugs, cap and rotor, impeller.

If it has never had a cap and rotor that is most likely your issue, I'm sure it is nasty on the inside!

-Chris

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Killer

I bumped the idle and it didn't solve anything. it is not a steady idle at all, depending on how you're running it, how you come into or out of idle, it will either be high or low..... sometime perfect too....

I pulled the dist cap and sprayed a bit of wd40 at it.... doesn't look that bad as far as corrosion, but he rotor contact has some good burn marks on the tip, and some melted plastic on it.... probably the problem there..

I also sprayed some carb cleaner as directed at/around the carb and that didn't seem to help either.

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martho

While your playing with things, you might as well start fresh. I don't see a need for wires if they were really replaced last year, however since you are troubleshooting, eight MR43LTS (I think that is right) is a small price to pay for the knowledge that you have good plugs.

Rotor/cap is easy to replace. As mentioned before SKI DIM can help.

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Killer

thanks Mark, I'll call dim today and order a bunch of the basic parts/maintenance items.

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Killer

wondering if I can buy most or all of this stuff at my local Napa?

I'd rather do this stuff now rather than wait for the parts to arrive, and if they dont remedy my problem I will have to wait that much longer..

would Napa have the dist. cap and rotor? part #s

fuel filters?

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M3Fan
wondering if I can buy most or all of this stuff at my local Napa?

I'd rather do this stuff now rather than wait for the parts to arrive, and if they dont remedy my problem I will have to wait that much longer..

would Napa have the dist. cap and rotor? part #s

fuel filters?

They will have the plugs, but not the cap, which is a marine cap. I'd adjust the idle air mixture first.

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Killer

I did adjust the idle speed up down, etc yesterday and both idle air mix screws. ran much better this morning, but I will go ahead and order the parts as its not perfect. seems like a timing issue because the rpm's jump up and down 100 +/- at idle.

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88Skier

That 100 rpm flucuation is normal, especially if it's hot and humid.

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pennery
wondering if I can buy most or all of this stuff at my local Napa?

I'd rather do this stuff now rather than wait for the parts to arrive, and if they dont remedy my problem I will have to wait that much longer..

would Napa have the dist. cap and rotor? part #s

fuel filters?

They will have the plugs, but not the cap, which is a marine cap. I'd adjust the idle air mixture first.

So there is a diference in Marine Cap's as opposed to Automotive cap's? Mt brother just used one that he found at an auto parts store and it fits perfectly...

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Killer

placed an order from ski dim for all of the above. its running better today after my little tune yesterday too.

Vince did say that the delco caps are notorious and often you can find all kinds of crap under them. he was not surprised by the burned rotor tip and melted plastic.

$65 for cap, rotor, 2 fuel filters and a set of plugs. he recommended the NGK over the oem spec AC plugs.

thanks again fells <- that should be fellas... I love this boat Beer.gif

Edited by H20ski Dude

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NorCaliBu
...he recommended the NGK over the oem spec AC plugs...

Thumbup.gif Absolutely. My Sporty runs smoother on the NGK's. Thumbup.gif

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