After rebuild on the 86 sunsport im Very happy except for one thing! CARB ISSUE?

[dshaff24]

The fact that this boat was stripped down and rebuilt minus the drivetrain and on its first voyage Every things works great!

But I do have a slight issue I want to address, I know these old 351's are cold hearted, But with 2 pumps this motor fires up perfect and runs great! Untill I Put it in gear then it will start moving and run at 600 rpm like its susposed to and then it will start to Try to shut down then Die!

don't get me wrong this is only after we been sitting and it Will fire right back up no problem and run I just got to keep it in neutral and idle up then go!

Also I do let the boat run for 2-3 minutes before I decide to put it in gear!

Is there something I need to adjust?

Everything is fine once the boat has been running! It just don't like to idle in gear when cold even after 2-3 minute warm ups

Maybe choke? I got a new one installed

[rludtke]

My electric choke isn't connected right now, and my boat does the very same thing. I just let it idle and warm up on the trailer until I reach ~150 degrees before I launch. I have to monitor the throttle for the first few minutes to keep her from idling to slow and dying. This only happens on the first start of the day. I suspect the electric choke can be dialed in to deal with this, but I'm ok with it as is.

The "electric" choke on the Holley uses vacuum to close the choke, and then has an electric "pull-off" mechanism to open the choke. A bi-metal coil in the pull-off heats up from the 12v current applied, and creates the rotational force to overcome the vacuum and open the choke blade (hence the name electric choke), and keep it open. The pull-off is adjustable. you can change the amount of tension on the bi-metal spring by loosening three screws, and turning the black knob on the right hand side of the carb. It has marks indicating rich and lean. Try making small adjustments. Turning toward rich will slow down the pull-off action.

[AaronWhitt82]

Maybe try turning the idle up a bit?

[michael hunter]

Yes you both have a choke problem Supras are not cold blooded if set up right.
The choke coil closes the choke plate when cold and uses the eletric heater to open it . You have to pump the throttle at least once to set the choke. The plate should be completely closed. After you start it the vac operated choke pull off should open the choke plate about 1/8 to 3/16 gap at the top of the plate. Note too small a gap and the motor will run rich shake and smell of gas. Too large a gap and it will hesitate and die when put in gear. Also when the choke is closed it should run at a fast idle there is a adjustment for that also. Refer to the Holley website or one of the numerous posts on line for detailed set up instructions.

[haugy]

Everyone above is right. Your choke needs dialing in. Also on the older carbs if the choke hasn't been replaced they can actually take longer. My choke spring had opened up over time, which loosened it. So instead of taking about 45 seconds to open up the choke when running, it would take over 2 minutes. I timed it. That's when I knew I needed to adjust the choke.

Look at the choke, the black housing on the side. Their should be indicator marks on it. You can turn the black housing left or right to dial it in tighter, or more loose. Too tight, and the choke will open to fast. To loose and you get the problem you are having. It only takes the smallest turn to dial it in.

Pull the flame arrestor off your carb when cold. Then turn the key to "On", do not turn the ignition. You just want power going to the motor. Then watch the electric choke. It should go from fully closed to open in between 45seconds to 1 minute. And it should move smoothly. If it takes too long, adjust it. If it doesn't really move at all or is jumpy and stubborn, you need to clean the choke assembly to help it move freely.

If all else fails, get a new electric choke, they are cheap.

[87SunSportMikeyD]

Wow these are great tips. I have the to pump mine to start it every start, but it doesnt die - much. THanks guys.

[Hematoma]

This is a prime example of WHY I don't run a choke. Just one more thing to fail and leave you scratching your head lol.

[Sunapee Sunsport]

Had the same problem with my boat dealt with it all last year. Not this year I backed both carb adjustment screws out 1/2 turn now the boat runs great. Warm her up to 160 put it in gear and she just chugs along.

[mapleleaf]

I love this thread, may teach me to tune my choke....gonna play around on the hose tomorrow......
Thanks guys......
Sorry Hema, we need some choke up here>>lol

[ngavchris]

Michael,
You mentioned that the butterfly valve should be close to 1/8". Is that after it warms up or when it first starts.
I have been helping NGAVDan with his boat and tried messing with this tonight. His is running very rich and I thought from what you where saying that it should be set there after it warmed up. The smell of gas fumes from exhaust decreased after closing the choke. Seemed to run fine after making this adjustment however it had to be turned off the dial to do this. WHere should the valve be after it is warm at an idle?
Thanks
Chris