Running Rich Need Help

[bigdawg]

hey guys just bought a 2000 supra launch this summer and it has ran like a top
but the last few times i took it out it has been smoking when at idle and smells like gas but it runs great i thought it prob need a tune up so change plugs and wires and it cut the smoke in half but still dose it when at idle any ideas oh yea it has a carb on it

[Longhorn21]

What color were your spark plugs when you pulled them out. If they were light brown then your fuel mixture is good. If they were black then your running rich and your idle mixture screw will need to be adjusted. Check first cause you don't want to mess with them if you don't have too.

[jet]

Mine is also running well but smells a little on the strong side when you pick up a rider. Any one know how to adjust??

[Ptownkid]

Yup, you need to adjust your idle mixture screw(s), IE a tune up. I have no experience with EFI engines so I'm not sure where they are or how to do it, but i have tuned a carb with no experience before so I'm guessing that if you look up your engine online you should find simple instructions on how to do it.

[bigdawg]

yea the plugs were black and smelled like gas anyone know how to adjust the idle air screws they are on the mettering block rite

[fastab]

On your 2000 it should have a chev engine in it which will probably have a rochester carb. the Idle mixture screws are on the front of rochesters. Holley's have them on the each side of the metering block this is what was used on the old pcm 351. Either way you want to adjust the screws with the engine running, turn them in/out 1/4-1/2 turn at at will listening to the engine and watching the tach, you want to adjust to the point that the engine runs the fastest and then richen them back up about a 1/4 turn. If they are fuel screws turning them in will lean it out, if they are air screws turning the screws in will make it richer. Do each side and then retest, throttle the boat up inbetween to clean out any excess buildup as well as allow you to test accelleration, if it hesitates a little and then takes off you need to richen the mixture back up. On the old (90&older) the points dwell could also be part of the problem.

[michael hunter]

Sounds like you are ready for a carb rebuild. If you have a Holley check the power valve if its a Rochester replace the float when you overhaul it.

[jet]

Hey fastab, I just did that adjustment..I did both needles 1/2 a turn until the engine was happy and running at best and the smoothest..but the fumes smell rich and are hard to take at the back of the boat, not real bad just more rich that lean. What do i do now..live with the richness? Or can I move one needle at a time? Thanks for your help on this one. Jet

Michael..lets just trade boats and rich problem will be done with. : )

[fastab]

Yeh you can do each screw individually, they each work the idle circuit in the different barrels of the carbs. I don't know if I mentioned it before make sure that the choke is openning fully and that the engine is a operating temp when adjusting them. If you have it close then doing one at a time alternating back and forth and running it up you should always come back to the same adjustment once you get it dialed in. If it is to lean it will hesitate a little out of the hole. The other thing that you can do is both sides should be close to the same adjustment. Check to see what each screw is in number or turns out, so you would screw it in counting how many turns until it little seats and back it back out do the other side should be close to the same if it is way different there maybe another problem.

[fastab]

Jet you have a 89 comp, does it still have points and condenser or has it been converted to electronic ign? If you still have points adjust the Dwell (points) this will effect the timing and carb adjustment.

[jet]

Converted!! Best $100 I ever spent. Choke open full (i set it myself) turned both sets of screws inward and started backing them out 1/2 turn at a time till smooth runs FANTASTIC but just smells a little rich. It might be at Its best but I always strive for better.

[fastab]

Run it a little while like that and see how it smells and runs, you can sometimes store unburnt fuel and fumes in the exhaust when the engine is running rich, it may clean itself out some.

[jet]

Thanks man....