Mercruiser no start!!! Help! Covered all obvious bases.

[zaxblue]

1989 Mercruiser 4.3l 2bbl
No start! Has spark and fuel. What else?

Went through everything. Covered all obvious bases.
Seriously, went through everything from completely clean dry gas tank... New/clean fuel filters, made sure carb was completely spotless inside, new iGnition compomponents, etc.
carb bowl was full of fuel when I opened it up the first time. After going through carb, it ran perfect for 10 minutes. Wouldn't start again after I turned it off for a few minutes. Went through everything again.

No start this time. Will run for a couple seconds on started fluid if I crank it for a while. Even that is a struggle. Normally starter fluid lights right up in this thing.

Curious if full carb bowl is normal???

Starting to think I may have exhaust blockage???..that's all I can think of at this point

Suggestions???

 

[Bt Doctur]

have you tried to fill the float bowl first

 

[zaxblue]

float bowl was full both times I opened the carb. Mechanical fuel pump is working and pushes fuel until the float valve closes when the bowl fills.

 

[Bt Doctur]

ok then, pour 2 Oz of gas down the throat , if it runs double check your fuel delivery

 

[zaxblue]

Thanks for your help! Unfortunately, I don't understand the advantage of gas over the starter fluid I used.

 

[Bt Doctur]

gas tends to burn ,ether(starting fluid) explodes . Used aggressively it will put holes in pistons

 

[thumpar]

Sure does sound like a fuel issue to me too. Since it ran after cleaning the carb you may try a rebuild kit.

 

[paul.detlaff]

have you tried setting the idle to a higher rpm or put the throttle to 50% when starting it. i usually have to run mine at 1200 rpm until the engine warms up.

 

[zaxblue]

Even though every jet and orifice was spotless the first and second time I went through the carb, I picked up a carb kit today.
Just got home from work. SHE STARTED RIGHT UP and is running fine. THE HECK?!!

I run this thing at least 20 hours a week from May through November. Intermittent problems are my biggest aggravation. Hate to just cross my fingers and hope instead of figuring this out.

Any suggestions?

I would assume that if she was just flooded, if I got it to run an starting fluid for a couple seconds, that would have dried the cylinders. But would love someone to tell me it could have still stayed flooded after that. Ha. ???

I'm stumped.

 

[zaxblue]

Just to clarify incase I didn't make it clear...I did NOT install the carb kit I just bought.

 

[zaxblue]

Update

Ran perfect for about 30 minutes. Died Won't run. Went through fuel system again. Still no luck.
Important: will start for a couple seconds if I pump the accelerator pump.

Anyone?

 

[Bondo]

.I did NOT install the carb kit I just bought.

Ayuh,...... Welcome Aboard,..... It sounds like a fuel delivery issue, so why haven't you rebuilt the carb,..??

 

[zaxblue]

Yes, it does sound like a fuel delivery system issue. That's why I've opened up the carb three times.

Carb was rebuilt less than a year ago. every jet and orifice was spotless. I did a half rebuild last night? Everything that was accessible After removing the airhorn. So, fuel filter, several gaskets, accelerator pump, etc.

 

[Bt Doctur]

does this have an electric fuel pump?

 

[zaxblue]

Mechanical fuel pump. It's keeping fuel pressure on the carb.

 

[UncleWillie]

Runs with ether.
Carb bowls have gas.
Runs pumping Acc. Pump.
Does not run normally.

This indicates that the fuel in the bowl is not reaching the throat.
The jets are plugged or something similar.
If you pull the plugs you will see that you are not flooded. Dry Plugs.
Put a piece of Plexiglas over the carb opening to form a see through choke.
The venturis should be dumping like Niagara falls while cranking.