Carb question......I'm stumped...

[sunbird 18]

Got a 94 Yamaha 250 carb. Here is the situation. I have to manually choke it via placing hand over carb intakes because the enrichening pump is dead. While doing this, I noticed that all of the carbs suck the palms of my hands in strongly except for #3 carb which has 1/3rd the suction compared to all of the others. Compression is 140-145 across th board. Plug is brown and healthy looking.
If compression is good, the only other thing I can think of is if it is easier for it to pull gas or air from somewhere else between the carb intake and the block than it is to pull my on my hand, but that would have to be a serious leak.
Any ideas??

 

[lowkee]

Re: Carb question......I'm stumped...

Blown gasket to the manifold? Only place I could think it would find air besides around your palm.

 

[rodbolt]

Re: Carb question......I'm stumped...

fix the dang ENRICHMENT pump.
thats what one of its functions is.
without it not only will it not start cold you will run lean on rapid acceleration and a few other areas of running.
if once started you dont hear a lean sneeze and see smoke coming out of a gasket joint its most likly ok.

 

[sunbird 18]

Re: Carb question......I'm stumped...

fix the dang ENRICHMENT pump.
thats what one of its functions is.
without it not only will it not start cold you will run lean on rapid acceleration and a few other areas of running.
if once started you dont hear a lean sneeze and see smoke coming out of a gasket joint its most likly ok.

I just got this motor running for the first time yesterday. I just discovered the dead enrichment pump last night. $200 for a new one...OUCH! I took it apart today, nothing looked bad, so it must be damaged coil windings or something. I'm going to replace it. No lean sneezes or smoke coming from anywhere except the exhaust...

 

[rodbolt]

Re: Carb question......I'm stumped...

anytime the key is on you should have 12V to the enrichment pump.
if not find out why, if so pump replacement is the only option.
I did not say they were cheap
but the 6 little solinoids on the carbs actually get pulsed by the ECU to enrich the fuel mix when cold starting and a few other things.
its gotta work.
and on your carbed V76 motor running without T-stats or stuck open t-stats can actually drain #6 fuel bowl and wipe #6 piston.