Hard starting when engine is warm

I have a low hour 1984 Century 3000 LX bowrider with a mercurycruiser setup. It indicates it is a 260, which from what I understand converts to chevy 350. I've had problems with fuel delivery to the carb but think have I have that fixed. The carburetor has also had a carb kit. The boat runs great when going out in the lake and pretty well when idling. But every once it awhile it might die when idling and it is then requires almost full throttle to get it to start again. Almost as if it is flooded. But.....I can shut it off after it has been running for awhile and then still have to give it full throttle to start it.......with no signs of flooding. One thing I thought of was the spring that extends and contracts and operates one of the flaps on the carburetor based on the engine temp. I thought it was good but maybe it isn't.

Is this the way it should be? I keep thinking this should be like a old chevy pickup that you turn the switch and it starts.....with no foot pedaling.

I appreciate your input.

Re: Hard starting when engine is warm

Unfortunately, unless you get a TKS, your relegated to having to pump some gas into the carb when you start it, and operate the throttle as necessary to start when warm.
From your description, sounds like you are referring to the "electric choke" on the carb, that gets "set" closed (or nearly so) when cold as soon as you open the throttle before starting the cold engine. Then it slowly opens as the electric "spring" warms up and opens the choke plate. You can search on this forum and find numerous posts on how that works, and your manual (also found in this forum) gives precise instructions on how to set it.
Another thing to check on this vintage year boat is the sight flow tube going from the fuel pump to the carb (clear tube). If it has fuel in it while running, you've got a bad fuel pump diaphragm. My boat had your same symptoms and that was the cause (needed a new fuel pump. Seems ethanol in fuel does not get along well over time with the rubber in the diaphragm.
Any other troubleshooting you need to do is well covered in the service manual you can find in the Adults Only sticky at the top of this forum. Good Luck!

Re: Hard starting when engine is warm

Sorry for the confusion over the choke. It is not an electric choke.....it appears to be a coil spring inside a little housing on top of the engine manifold. The spring is hooked up to a little rod that leads up to the carb. I've looked through all the forums and thank you for your advice. It sounds like it could be one of two issues right now, either a weak fuel pump or a possible leak of fuel from the carb into the manifold after the engine has been shut off. I had the marine mechanic put in a new carb kit but maybe I should have him adjust the float a little lower? I'll first look at the sight tube you requested.

Re: Hard starting when engine is warm

So I take it your choke looks like the one on page 4C-15?:
http://boatinfo.no/lib/mercruiser/manuals/mercruiser3.html#/540

Re: Hard starting when engine is warm

Yes. That is the one alright. Same carb and everything.

Re: Hard starting when engine is warm

Hard starting when engine is warm
I have a low hour 1984 Century 3000 LX bowrider with a mercurycruiser setup. It indicates it is a 260, which from what I understand converts to chevy 350


...are you sure thats not a Ford 351 block ?.....if it is...... check and change out your fuel water seperater filter....makes all the difference .....alot of ppl overlook that filter....good luck....
FM

Re: Hard starting when engine is warm

It is a chevy small block. I recently changed the fuel filter. thanks.

Re: Hard starting when engine is warm

jwjbs said:

It is a chevy small block. I recently changed the fuel filter. thanks.

Click to expand...

ok...on the chevy block!...
I am talking about the fuel / water seperater filter.....fuel filter is in carb.??....fuel water seperater filter is completely different filter.....in line between tank and engine...looks like an oil filter or sometimes a glass bowl with a paper filter.....

I don't know..maybe your boat doesn't have one ...but I bet it does!....that's why I said alot of ppl overlook them...they don't even know it has one..

Re: Hard starting when engine is warm

yes. Both have been changed. The filter on the carb, and the spin-on water separator filter.

Re: Hard starting when engine is warm

Do you have a hesitation at all when you do a hole shot? The reason I'm asking is that I had the same hard start when warm, and also a hesitation on hole shots, that I fixed by advancing the timing a few degrees. Also, I use 100% gasoline with fuel conditioners.

Re: Hard starting when engine is warm

Rebuild the carb...Tank it, blow out ALL pasasges with compressed air. Make sure your float is set correctly, and that it's a BRASS one.

Re: Hard starting when engine is warm

jwjbs said:

yes. Both have been changed. The filter on the carb, and the spin-on water separator filter.

Click to expand...

well now there's one less thing you have to worry about..
good luck .......
FM

Re: Hard starting when engine is warm

There doesn't seem to be any hesitation when I give it throttle. I just had the carburetor rebuilt last week. I'd hate to take it apart again but maybe it isn't fixed. Maybe I'll do it myself this time. Very frustrating. Think I'll put on a new fuel pump also.