1974 6hp carb flooding but spark plugs dry

[scott_maier]

Motor won't start or fart. I've got 75psi on each cylinder, spark looks good but I did not use a spark tester- the coils look okay and points have been checked and re-gapped, i also "rebuilt" the carb with a new kit. Fuel is getting to carb and after a 5 or more pulls on the starter rope fuel will drip out the carb throat, but the plugs stay completely dry. Does this mean the leaf valves are stuck closed? I haven't tried spraying starter fluid or anything, because it should be sucking plenty of fuel in.

I don't know the history of the motor, but when I pulled the head off it was crudded up pretty good so I wouldn't be surprised if the leaf valves were dirty or stuck. I was just thinking for some reason that it is rare to have problems with the leaf valves...i must have heard or read that somewhere.

Anyway, any suggestions would be appreciated, I'm hoping I don't have to pull the powerhead again and check the leaf valves.

thanks in advance.

 

[wilde1j]

Re: 1974 6hp carb flooding but spark plugs dry

Spray premix into throat while pulling over. Reed valve are extremely unlikely problem. I'll bet it fire.

If plugs are dry, it's not getting fuel. Redo the carb rebuild and soak the carbs overnight in carb cleaner and clean all orifices. An OEM shop manual will be a help.

 

[Joe Reeves]

Re: 1974 6hp carb flooding but spark plugs dry

There is a brass high speed jet located in the bottom center portion of the carburetor float chamber. Fuel must flow thru that jet before the fuel can find its way to any other fuel passageway. I strongly suspect that this HS jet is clogged.

I assume you have been choking the carburetor, and if so and the carburetor was flooding, the spark plugs would be soaked with fuel. Also leaf valves do not stick like that.

THe spark on that model should jump a 1/4" gap with a strong blue lightning like flame.... a real SNAP! The 1/4" gap is important.

 

[scott_maier]

Re: 1974 6hp carb flooding but spark plugs dry

Thanks for the above replies.

When I put the new rebuild kit in the carb I pulled the HS jet out and it was clear. One thing I found was that there was a piece of the old LS needle stuck in the hole (or jet). I managed to get that out, but maybe some permanent damage was done by the piece being stuck in there, but it looked ok. I also took that punch cap off the top of the carb, cleaned out the debris that was in there and put a new cap in place. I do have an OEM manaul. These carbs are so simple, but maybe a passage is clogged.

I'll get a spark tester and make sure that's okay... but Like I said before the fuel was dripping out of the carb throat/intake (the motor wasn't perfectly level sitting on the 2x4 that was on the water tank) so I don't understand why the plugs weren't getting wet.

Thanks for the replies.

 

[Tim Frank]

Re: 1974 6hp carb flooding but spark plugs dry

Motor won't start or fart. I've got 75psi on each cylinder, spark looks good but I did not use a spark tester- the coils look okay and points have been checked and re-gapped, i also "rebuilt" the carb with a new kit. Fuel is getting to carb and after a 5 or more pulls on the starter rope fuel will drip out the carb throat, but the plugs stay completely dry. Does this mean the leaf valves are stuck closed? I haven't tried spraying starter fluid or anything, because it should be sucking plenty of fuel in.

I don't know the history of the motor, but when I pulled the head off it was crudded up pretty good so I wouldn't be surprised if the leaf valves were dirty or stuck. I was just thinking for some reason that it is rare to have problems with the leaf valves...i must have heard or read that somewhere.

Anyway, any suggestions would be appreciated, I'm hoping I don't have to pull the powerhead again and check the leaf valves.

thanks in advance.

1) Use a spark tester, then you know.
2) Make sure plug leads aren't reversed.
3) Back to carb....and wilde1j's suggestion of the premix would prove a carb problem.

 

[scott_maier]

Re: 1974 6hp carb flooding but spark plugs dry

I bought a spark tester at autozone ($7 item) and found that the coil connected to the top plug throws a nice blue spark across a 1/4" gap and the bottom coil can only cross about a 1/8" to 1/16". Just for grins I put the spark plug back in the bottom wire and ground it to the engine and checked the spark. It sparked, but you'd never be able to tell how weak it was without the tester. Anyway i digress...

So then i put the plugs back, filled a spray bottle with pre-mix (50:1 fresh gas and oil from the tank) and sprayed it in the carb. It burped and after a little playing around i got it to run for about five seconds. I didn't have the gas tank hooked up so it was just running off the pre-mix. It actually ran pretty smooth, so at least I think I got the points right and now know the carb has issues. I'll be taking it apart again and see what I can find.

Thanks for the help!