poor idle on 4.3L 190 HP

[NC1800SR3]

I"ve got a 2008 1800 SR3, with the 4.3L carburated (190hp) engine. Its only got about 18 hours on it, and has been running well. The last two times out, however, I've had poor idle performance. It will start, and runs fine at normal RPM's, but when I slow down to no-wake or idle, it stalls. It will restart but immediately stop unless I advance the throttle, and once I get up to speed it seems to run ok. I've got some gas in the tank left over from last season, but it had stablizer added as part of my winterization. I've filled the tank so there is new and some old gas in the tank. Is it possible I'm seeing effects from gasoline with 10% ethenol, or water in the tank?
It runs well at speed, its just idle thats a problem. Is there a fuel/water seperator on this model?

[Brit Rider]

SOunds like you hit the name on the head.

E-10 evaporates and boats fuel systems are sealed like in a car. you are likely suffering with bad gas.... I'd just get it run through and back onto normal pump gas asap.

[seapuppy]

bad gas....


SP irate:

[shrew]

Just a thought here, but wouldn't bad gas run rough at almost all RPM's?

It will start, and runs fine at normal RPM's, but when I slow down to no-wake or idle, it stalls. It will restart but immediately stop unless I advance the throttle, and once I get up to speed it seems to run ok.

This sounds more like a clogged Pilot Jet, than bad fuel. The pilot jet would be used to deliver fuel at idle, while the main jet will deliever fuel on throttle (technically the pilot always delivers a fixed amount of fuel). As teh throttle is opened, the main needles should get slowly lifted from the main jet. Both the main and needle are tapered and should increase fuel exponentially as the throttle is increased. A the same time, the throttle body should be openeing the air aperture to maintain a balanced fuel to air ratio.

When I hear a description like this, where at idle it stalls, but slightly advancing the throttle allows the engine to remain running at idle, it sounds an aweful lot like the pilot jets are clogged and the main jet needs to be opened slightly to compensate. The clogging can absolutely be a result of old gas sitting in teh carb. Especially if the engine wasn't run long enough after adding the fuel stabilizer to purge the gas in the fuel line and fuel bowls on the carb to replace the fuel in the fuel bowls with the stabilized fuel. (On motorcycles, I shut off the fuel and run them dry to winterize).

Carbs are carbs whether they're in boats, bikes or cars. I would suspect a clogged pilot jet, based on this description.

Just my .02 I'm very curious to hear feedback from the poster on this one.

[NC1800SR3]

Thanks for the suggestions. I too, was wondering why it would be just an issue at idle. I've been so busy at work, haven't had time to get out there and work on it. Will update what I find.
Thanks all,

T

[yorkcoparamedic]

I had break down the E-10 w/ a lot of separation, combined with a small water leak around the fuel cap from a bad rubber seal. Completely gummed up the jets! I agree with the last poster about the jets being clogged. Sounds like your on the way to a completely clogged carb.

I would also check the water separators and see if the there is water present. You can also pop the fuel sender off the tank and look down inside for a pool of water that may be present. Best to check and make sure that it doesn't happen again right after you rebuild or clean the carb.

[Argonaut]

Originally Posted by shrew

Just a thought here, but wouldn't bad gas run rough at almost all RPM's?

On this engine eeven easier to achieve that ... simply unplug the lead to the fuel pump when engine is running ... it will run until fuel used up.

Might be worthwhile running some Wyns / STP / Redex throug the system that would clear a gummed up jet

[bnsf215]

Seafoam + premium fuel no ethanol, should be good. Our 03 with the 3.0 did the same until we quit buying fuel from the closest place with ethanol and went to premium 92.