Okay, fuel pump is still good! lots of fuel! I also took off the banjo fitting at th carb and all is well there.

So I think your original deduction was correct, accelerator pump. However, why would it be able to run and rev up after start up?

 

Okay great it looks like we have narrowed it down to the accel pump!

The reason the engine starts easy after shut down is: Its already primed! there is a viable ~ 14.7 air fuel charge sitting in the intake , the cylinder walls are hot making it easier to ignite the fuel, oil is hot as well and flows nice...its basically just waiting for spark and compression.


So im now 95% sure all your issues are related to a bad accelerator pump. If you shut the engine down and dont see any fuel squirt into the carb barrels from the accelerator pump when you run the throttle to wide open I suspect the accelerator pump piston is worn out or there is a blockage in the accel pump jets or both.

A rebuild kit for your carb is in order it should have all the pieces + the accel pump parts.


What carb is it?

-Gun

 

COOL! 1405

 

Thats an easy one.

Pick up the rebuild kit at your local Oh Really? auto parts I think they cost about 40 bucks.

Replace everything thats included in the rebuild kit.

-Gun

 

I was just looking at the kits and they do not include a replacement for the accel pump. I can buy one of those for 10 bucks. I should rebuild it anyway!

 

Check this out! Im going to try this first.

"Pulled the air horn, then removed the small cap that holds the discharge jets for the accelerator pump, pulled out the weight and check ball. Then blasted the carb body out with carb clean then compressed air. Shot a wad of crap out of the accelerator pump passage whilst doing so. Reassembled and installed. Problem solved...nice strong jet of fuel, no stumble or bucking during acceleration."

 

Hum I though they came with everything like the plunger and all that stuff. (it looks like a rubber disc with a skirt around it)

It could just be clogged...and a simple airhorn removal could do the trick.

I just figured if the accel pump is plugged or so old it doesnt work anymore then who know what else is worn and since you have it 90% apart might as well do a complete rebuild. That's what I would do but its not required...all that's required is determining why the accel pump dont work and taking corrective action while not screwing up anything else.

-Gun

 

Ya I probably will do a full rebuild, but I want to try this first.

Just FYI the accel pump is totally different on a eddy vs holley type carb. it looks nothing like what you described above, it is long and thin with a plunger looking thing and spring, thats it. I rechecked and some kits do have one with it.

Thanks for all your help with diagnosis of my problem! I really appreciate it.

 

FIXED! the plunger skirt on the accel pump was dislodged. also the check ball was gunked shut. i cleaned it real good and voila it worked!

thanks for all the suggestions!

 

great!