Starting procedure advice req please

[Welsh Rob]

1992 5.7 Mercruiser thunderbolt 1V ignition Rochester 4 barrel carburetor.

Replaced within the last week..................
Spark plugs
Ignition leads
Distributor cap
Rotor arm
Factory reconditioned Rochester carburetor fitted also.

Hi All,
She starts from cold with no problems after giving one full push of the throttle and within a minute she will settle to a very smooth idle at approx 600/700 rpm

Switch off and start her again ina minute or two with hardly any throttle and a couple of turns of the engine and she again fires and runs fine.

Switch off and leave for an hour or so and try to start her is when I get problems........I'm very worried of flooding it so I give it no throttle just in case but then she will just turn over and over and will not fire at all !?
I move the throttle to about three quarter and still nothing !?
Then strong fuel smell and hey presto I've flooded it so then its off with the flame arrestor open the chokes all the way by hand open the throttle all the way and turn her over until she leans back down and fires then I quickly close the chokes and pull throttle back she idles again very nicely indeed........................?

So my concern is what may I be doing wrong?

Should I give her a squirt of throttle again?

Or could this be a coil issue breaking down when warm(coil looks to be the original) though all connections have been cleaned etc.

Many thanks in advance again
Rob

 

[Mahoney]

Re: Starting procedure advice req please

I would try giving it one good full pump then pump it down to FULL throttle and leave it there while cranking. when it catches, immediately bring the throttle back down.

 

[Mahoney]

Re: Starting procedure advice req please

also, check your choke, it sounds as if it might be sticking open after it gets warm and starts to cool back down again.

After you let it sit to where you expect problems starting, open up the engine cover and note the position of the choke. give it a manual quick "spring" and see if it changes the position of the primary throttle plates.

 

[Welsh Rob]

Re: Starting procedure advice req please

Mahoney,
Thanks,I have checked the choke position as suggested and the plates are sort of half way open,the mechanism seems to be working ok and as the engine gets cooler they are closing slowly...........this is the way its meant to be I hope?
Are these engines very sensitive to flooding?
I have still not tried to start her with a wide open throttle when engine has been stopped for a while for fear of flooding..should I ?
Also have now replaced the coil !
Very frustrating this !!!!
Rob

 

[Silvertip]

Re: Starting procedure advice req please

The Rochester 4bbl carb had a problem with casting porosity meaning the fuel in the float bowl could seep through and flood the engine. Some auto carb kits came with extra pieces to fix the problem. On a hot engine, the choke plate should stand perfectly vertical with the engine running. If its not, either the vacuum pull-off is not working or adjustment is needed. When stone cold, moving the throttle forward (before starting) should cause the choke plate to pop shut. After startup, the pull-off should pull it partially open. You need a manual for these adjustments