MN-Brent

I posted this in other cars, but thought I might get some good advice over here , so here it is:

https://www.corvetteforum.com/forums...ta-2004-a.html

I have a 2004 Glastron with a GM 5.0 (305) Volvo Penta with Holley 2 barrel. I took it out of heated storage (my garage) this weekend, finally. It will start easily and runs very smooth.

I'm noticing this issue and not sure where to start with it:

1) When cold- it starts and idles with zero throttle at around ~600rpm and will stay there for a few good minutes without any throttle input.

2) When still cold and within a minute of starting, I give it some throttle to rev it up once, going back to zero throttle, the idle will now stay at ~1200 rpm. It will stay at this rpm whether in gear on in neutral.

3) When at running temp (160F), after ~10 minutes of running, the electric choke would have timed out long ago, the idle will still sit closer to ~800-1000 rpm after a rev up and going back to zero throttle.

It has electric choke and I have made sure the leads are nice and tight for power so there should not be an intermittent restart of the electric choke.

Does this sound more like a classic choke problem or would a simple idle speed adjustment be the place to go next?

I want to adjust as little as possible from the settings that are mostly working.

Appreciate any assistance!

MelWff

with no key in the ignition, have you looked at what the choke is doing when completely cold after depressing the gas peddle fully to the floor once and NOT starting the car. The choke blade should full close with a light pressure in warm weather conditions, 72 F.
You are stepping on the gas peddle fully, one time, before attempting to start?

MN-Brent

Its a boat, so what I do is give the throttle 2 pumps, to let the carb accelerator pump do two squirts down the carb throat to prime it for starting.

This would be with the ignition on, so the choke should be activating. I'll try to eyeball this.

johnt365

When it is idling between 800-1000, what happens of you reach in and press the red lever for fast idle down?

If pushing that down lowers the idle, then I think you are looking at a choke related issue.

If it idles up and you reach down to press that red lever and find its already bottomed out, then you have other issues it would seem to me.

Duane4238

It sounds like it's not coming all the way off of the fast idle cam. If you didn't have this problem when you put it away last fall, I'd spray some carb cleaner on the linkage for the choke. It may have some residue gummed up on it from last season.
Duane

maxmachz

Unhook the throttle cable and do it by hand. Could be a bad cable that does not return the throttle linkage consistently to the same spot.

mikem350

Or weak return spring

PAmotorman

a lot of marine carbs do not have a fast idle cam because you keep the idle speed up with the hand throttle

PAmotorman

a lot of marine carbs do not have a fast idle cam. you keep the RPM up using the hand throttle