1988 Bayliner Ciera Sunbridge 2150 w/GM 302AMRGDP - Surging Idle

[Craig1972]

Hi guys! I've got a rough/surging idle question. The engine is a 3.0 liter GM, with a 2bbl.Holley carb. I bought the boat from a dealer, where it had been sitting for several years. After replacing all the filters, spark plugs, distributor cap, rotor, and wires, I still have a "surging idle". Especially after it reaches operating temperature. I noticed some "varnish" build-up, coming from the float adjustment on the top of the fuel bowl. If the problem was water/bad gas in the fuel tank, what corrective actions should be done? What cleaning solution should be used to clean the 'gum' from the carb?

 

[jerryjerry05]

Welcome.
Any warranty from the dealer?
Yes?
A carb rebuild would probably be the best.
No?
Then remove all the old fuel.
Clean/ rebuild the carb.

If fuel's coming out the top of the carb then a rebuild by a pro is really needed.

There is a carb/injector product called Chevron with Techron.
Comes in a black bottle.

I mix 1 jug of the cleaner in 1 gal of gas.
Then undo the fuel line from the tank and hook the container to the fuel line.
This concentrated fuel will help clean up the carb.

Bought a Ford Ranger with fuel injection.
Didn't run as smooth as it should.
Ran it almost out of gas and added the fuel cleaner.
Went for a ride. I could actually feel the motor smooth out and run better as I drove around.

The 88 Bayliner came with a Cobra drive.
Very important to fill the lower unit oil the correct way.
From the side of the unit.
If not it will destroy the upper.

 

[Bondo]

Hi guys! I've got a rough/surging idle question. The engine is a 3.0 liter GM, with a 2bbl.Holley carb. I bought the boat from a dealer, where it had been sitting for several years. After replacing all the filters, spark plugs, distributor cap, rotor, and wires, I still have a "surging idle". Especially after it reaches operating temperature. I noticed some "varnish" build-up, coming from the float adjustment on the top of the fuel bowl. If the problem was water/bad gas in the fuel tank, what corrective actions should be done? What cleaning solution should be used to clean the 'gum' from the carb?

Ayuh,... Welcome Aboard,..... How much, 'n what sorta crap did ya find in the fuel filters,..??

Disconnect the boat's tank, from the fuel pump inlet, 'n run off a remote tank for testin' purposes,...
It would also be a Great idea to add a canister type fuel filter, just before the fuel pump, for continued clean fuel,....

While ya got that hose off, suck some gas outa the tank, 'n inspect it,....
If it Smells like gas, it oughta still burn,... If it Stinks, it's junk,...
Pump out the tank, or remove the tank, 'n clean it out,....

Sounds like yer carb needs a Rebuild,...
To do it Right, ya need the rebuild kit, a carb dippin' cleaner, 'n compressed air,....