Engine won't restart when Warm

[Charrob]

Hi,

We have a 1978 Catalina 27' with an Atomic 4 Engine.

Our engine never has a problem starting up when cold. Like usual, when we first started her up a few weeks ago after she sat in the water all winter, she started up first try without a hitch. Similarly, when we first start her up to take her out for a sail, she starts up beautifully.

However, after sailing a few hours when we need to get her back into the narrow creek and marina, her engine cranks and cranks and won't turn over. This has been going on for several years now. And there are occasions when we especially need to have a very quick to start engine -- like when we're not paying attention and look up to see a container ship coming toward us.

Eventually after trying, then waiting, then trying, then waiting, etc., we have been fortunate enough to get her started in the past. But in these situations, a lot of times I've noticed that when she DOES start, she coughs a bit at first as if she's possibly flooded. But once she's started, then she's good to go -- she's a really good motor.

I co-own the boat with my boyfriend and he learned several years ago on this forum that if she doesn't start the first time, then to close the thru-hall until she does start. And we religiously do that.

Here are our questions:

• Should we use choke or not after the engine is warm?
• What rule of thumb should we follow for starting... how much throttle... how much choke... how can we tell if we’re flooding the engine?

Thanks!

[JOHN COOKSON]

A Big Welcome To The Forum

An updraft carb, like the one on the A4, is almost impossible to flood and will need brief full choke to start when fully warmed up. More choke will be necessary to start a cold engine.
Have you been using the choke to start when the engine is warmed up?
Try with ~45* throttle setting when starting a hot or cold engine then adjust from there.

TRUE GRIT

[Al Schober]

My engine need choke to start when it's cold - not so much after it's warmed up. I should mention that I have the adjustable main jet, so am running it about as lean as it likes.
Seems to me that if your cold engine starts easily without choke, then you're running quite rich on the mixture. If you have an adjustable main jet, I'd try turning it in a bit. With a fixed jet, it may be oversize or your fuel level in the float bowl may be too high. Perhaps someone else will suggest another reason for the engine to run rich. I'd be curious to see how your spark plugs look after running for a while - just shut it off and pull a plug. Picture would be good.

[Charrob]

Thanks so much for both of your responses. We always use full choke to start up the engine when cold. And she starts fine when cold.

My boyfriend is the main engine person; the following is his response for when the engine is warm:

"hi, yes, i've tried w and w/out choke. and, tried w throttle at abt. 25... and more. it seemed the engine wasn't getting fuel as when it finally sputtered after a long crank, i had to give it full throttle to keep going. We had the fuel lines re-routed last year... and new fuel tank. the lines go in front by the engine door, along that bottom doorway lip, and up to the electrical fuel pump not far from the carburetor. wondering about possible vapor lock. might the fuel pump be too high? it's higher than the tank. or the line getting too warm in front? the engine starts great when cold. one or two cranks. it's v difficult after being run. we ran for around 45 mins, then off for nearly 2 hours when we had the difficulty. my initial hunch was that it was a fuel problem and possible vapor lock... that fuel wasn't getting to the carb. but, just a guess. that i had to give full throttle for the engine to catch suggested a lack of fuel was the issue."

[Al Schober]

Vapor lock? That would be a first in my book..
Several of the folks in this group have added pressure gauges to the inlet of the carburetor. Little 1.5" diameter things that answer the question "Am I getting fuel?".

[Charrob]

Thanks Al for responding. And would a gauge like this tell us if we are getting too much fuel, the right amount of fuel, or too little fuel as well?

[hanleyclifford]

If this scenario has been going on for several years under nearly identical circumstances I would suspect the following. The problem occurs after sailing, that is after the fuel in the tank has a good slosh-around to put crud into suspension in the fuel. Could be time for a thorough fuel tank cleaning.

[Charrob]

If this scenario has been going on for several years under nearly identical circumstances I would suspect the following. The problem occurs after sailing, that is after the fuel in the tank has a good slosh-around to put crud into suspension in the fuel. Could be time for a thorough fuel tank cleaning.

Thanks HanleyClifford but that's not the answer. We just got a brand new fuel tank at the end of last year as well as all new fuel lines.

[Charrob]

Al Schober here's Rob's response from earlier questions (I'm Charlene):

Rob: "Don't think the mixture is too rich; not a lot of smoke from the exhaust. Don't think the plugs will be dripping with fuel after running. I think it's electrical or lack of fuel...such as vapor lock. She's started well in the past with no choke when warm. But maybe since she was off for 2 hours, she needed full choke to start again?"

[hanleyclifford]

Have you investigated all tune up specifications, especially dwell? Do you have electronic ignition?

[Charrob]

Have you investigated all tune up specifications, especially dwell? Do you have electronic ignition?

thanks Hanley. Rob sent me the following link:

http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=IGEM_12_37

With that, here is his response:

Rob: "The spark plugs are just a year or two old. The electronic ignition from the link looks like it replaces the condenser and points (and so, more reliable)... but we need to check that it’ll work with our engine."

Hanley can you tell us if the electronic ignition from the link will work with our engine?

What do you mean by 'dwell'?

[hanleyclifford]

The electronic ignition will work with your engine. Dwell is the number of crankshaft degrees that the points remain closed for each firing of the coil. EI has no points and the function is performed by the module but typically the EI yields far more dwell than points. Can you say whether your issue coincided with the installation of the EI?

[Charrob]

The electronic ignition will work with your engine. Dwell is the number of crankshaft degrees that the points remain closed for each firing of the coil. EI has no points and the function is performed by the module but typically the EI yields far more dwell than points. Can you say whether your issue coincided with the installation of the EI?

Hanley thanks for responding. Rob hasn't yet purchased or installed the electronic ignition that was shown in the above link. He wanted to know before purchasing it if that would work with our engine. But you are saying yes that that part will work with our engine if we purchase it?

[hanleyclifford]

If you are currently using points ignition the issue of dwell could relate to your problem. Dwell meters are cheap and easy to use. Insufficient dwell can mean weak spark especially on a warm engine.

[Charrob]

If you are currently using points ignition the issue of dwell could relate to your problem. Dwell meters are cheap and easy to use. Insufficient dwell can mean weak spark especially on a warm engine.

Thank you!!! Where can we buy a dwell meter?