Starting issues - please help.

[DrD]

For my 1991 Mercruiser 5LX Thunderbolt powered boat I don't have any operators manuals. I would like to know what a 'normal' starting procedure should be. When cold, I have to pump the throttle a number of times while cranking before it starts.

The last time out, After a 5 mile run, I shut the engine off for about 30 minutes. When I tried to restart it, it just cranked on and on. I tried pumping the throttle, until I was sure it was flooding. Finally, I put the throttle all the way down, and it started.

I'm probably trying to start it incorrectly. Is there a recommended starting procedure for this carbureted engine? If so, would someone please tell me how it should to do it?

If this sounds like a carburetor problem, would someone help me identify the carburetor, and I'll try rebuilding it or replace it, if I can find a rebuilt carb. Thank you very much for your help.

-Dale-

 

[enforcer30]

Re: Starting issues - please help.

It's pretty much normal to have to pump the throttle a few times before starting. 2 or 3 pumps if the engine has been sitting shut down. Your carb is under the black cover on top of your engine.
On the starboard side (if you are in the boat looking at the engine your left) of the carb there are two wires that that plug into the electric choke make sure they are pluged in.
How many RPMs does your engine idle at?

 

[Reel Poor]

Re: Starting issues - please help.

There are no wire on your carb for the choke, that is a mechanical choke system.

 

[DrD]

Re: Starting issues - please help.

Thanks for responding. I still don't know what carburetor this is (image in first post). I talked to a mechanic who said it probably was normal and necessary to use WOT to start it when it was warmed up.

He also said that the GM Quadrajets have some known issues with lead plugs and that there were several attempts to fix the problem. I'm not sure if this is a quadrajet, but considering that it's on the GM engine, it probably is. I hope I can still get a carb kit for it.

-Dale-

 

[Gary H NC]

Re: Starting issues - please help.

Looks like a Q-Jet. Rebuilding them is tricky if you have not done one before.
For about 200 you can get a remanufactured one and just bolt it on.
Look at these,
http://www.marinecarburetor.com/pictureid.htm

 

[DrD]

Re: Starting issues - please help.

Thank you very much. That info is very helpful. I took a lot of pictures of my carb, and the one offered at the site you've given looks just like my Q-jet carb.

I would still appreciate any further tips on starting the engine, cold and warm starts. There may not be anything particularly wrong with this carb, except for my inexperience! It was a little scary out in the middle of the Columbia river, with an older warmed up cranky engine, that was difficult to start!

-Dale-

 

[Gary H NC]

Re: Starting issues - please help.

I would still check out the choke to see what its doing,both cold and warm.
See if it starts out being closed when cold and after a run with the engine up to temp it should stay open.

My old boat had a 2 barrel Rochester,I pushed the throttle all the way forward to set the choke,then a couple pumps to start..

 

[79Glastron]

Re: Starting issues - please help.

Yeah, its a quadrajunk carb, I have no idea why they put those on boats, worse idea ever. I would rather have a holley than that, my top choice would be a carter afb clone, much better carb, of course, use the marine version.
For cold starting, pump the throttle slowly 2-3 times, then return to idle and start. The fast idle cam should keep the rpm's around 1000. After a few mins, rev engine once to return to normal idle rpm. For warm engine, open throttle slightly above idle, about 1/4 open, start, return to idle once running. There is no reason a carb engine shouldn't start as well as a EFI engine. Only use WOT if engine is flooded!