4.3l mercruiser no start when hot

[nola mike]

Still no update on accelerator pump function... What happens if you pour a little gas down the carb throat?
Also this isn't a tks is it?

 

[TMcDaniel]

Still no update on accelerator pump function... What happens if you pour a little gas down the carb throat?
Also this isn't a tks is it?

Not a tks. I will be home later this afternoon to give update on accelerator pump.

 

[TMcDaniel]

Not a tks. I will be home later this afternoon to give update on accelerator pump.

Not a tks. I will be home later this afternoon to give update on accelerator pump.

the accelerator pump is functioning properly.

 

[Scott06]

if it is shooting gas in when hot then would think you must be loosing spark somewhere otherwise it would at least cough

 

[TMcDaniel]

It will cough once but not start. Just checked spark on all cylinders after it warmed up. All 6 were sparking. Instead of using starting fluid I used gas as suggested set throttle wide open and after a couple revolutions it fired right up. Does this suggest the carb bowl running dry? If so do I need to reset the float? Carb was rebuilt last year.

 

[rolmops]

What about the fuel pump? You stated that you only run it on the muffs at low rpm so you might not have noticed, but possibly the pump is bad and does not get enough fuel in the carburetor.

 

[TMcDaniel]

What about the fuel pump? You stated that you only run it on the muffs at low rpm so you might not have noticed, but possibly the pump is bad and does not get enough fuel in the carburetor.

I’ll check pressure tomorrow after work.

 

[TMcDaniel]

I’ll check pressure tomorrow after work.

Fuel pressure is between 4 and 5 psi.

 

[alldodge]

Pressure is good

 

[TMcDaniel]

Should I be looking into the carb float now?

 

[nola mike]

Should I be looking into the carb float now?

Still breathlessly waiting to see if your accelerator pump is working/shooting gas down the carb when you pump the throttle. If you don't want to tell us that's cool.

 

[tank1949]

It sounds to me that the fuel level in the carburetor is being drawn down by the engine running and when you try to start there is no fuel available.
What happens if you try to push to full gas a couple of times before trying to start? And what happens if you allow the engine, when hot, to run at an idle rpm for a minute or two? stop it and then try to start?

Not clear what model you have??? Check timing, may be something stuck.

 

[TMcDaniel]

Still breathlessly waiting to see if your accelerator pump is working/shooting gas down the carb when you pump the throttle. If you don't want to tell us that's cool.

I thought I already posted about that. Yes the accelerator pump is working. Do you think running a higher octane gas would help? I usually run the cheap stuff.

 

[dubs283]

Based on your provided info/testing it seems you've ruled out fuel supply as the issue. The issue most likely is ignition related

Cap and rotor are new wires are only a year old I’ll get a new fuel filter today. It idles around 700rpm without fail.

No mention of spark plug age/type nor mention of timing check/adjustment

 

[Scott06]

I thought I already posted about that. Yes the accelerator pump is working. Do you think running a higher octane gas would help? I usually run the cheap stuff.

No octane only relates to how high compression and how much ignition advance u run

 

[nola mike]

If the accelerator pump is working and squirting gas, then it should fire if it fires with gas poured down the carb. How long did it run with gas poured down the carb?

 

[TMcDaniel]

If the accelerator pump is working and squirting gas, then it should fire if it fires with gas poured down the carb. How long did it run with gas poured down the carb?

It stayed running after the gas was poured into the throat. The plugs are good the timing is correct.

 

[cyclops222]

Redo the carb FLOAT LEVEL resetting procedure.

 

[nola mike]

It stayed running after the gas was poured into the throat. The plugs are good the timing is correct.

But not when squirted down when pumping the throttle? That doesn't make sense, you're doing exactly the same thing. Just for fun maybe try to jump the fuel pump before starting next time.