Help! #3 is dead

[austin552]

I pulled the plugs and all were black but #3. After changing them all I started the car and pulled #3 plug wire. Nothing, had no effect. Swapped plug wires with no effect. The carb barrel is sucking air. What now?

[docrodg]

I am assuming that when you pulled the #3 wire you checked for spark. If no spark on #3 even after swapping with a known good wire you should check the cap... Probably have a bad terminal in there. If you have spark then the problem is deeper in the engine, like a bad piston, or that carb is clogged and sucks air but does not draw fuel. You can check for fuel by opening the throttle a little and slipping a piece of paper in the throat down by the passages... wet paper means fuel. If you have fuel and spark then you are probably going to buy a new piston and cylinder soon.

[BURN-BROS]

I would start with verification of fuel to that cylinder
Verify valve lash
compression test
cylinder leakdown
Inspect combustion chamber with a bore scope if compression/leakdown fail.

[austin552]

With the motor running I wiggled the #3 wire connection at the cap to make sure it was connected. Got a nice shock through the boot. I will check the fuel to the cylinder tomorow.

Thanks guys

[docrodg]

Originally Posted by austin552

With the motor running I wiggled the #3 wire connection at the cap to make sure it was connected. Got a nice shock through the boot. I will check the fuel to the cylinder tomorow.

Thanks guys

Shock through the boot at the cap does not mean spark at the other end. When you dig into it tomorrow check fuel, then pull the plug and connect it to the wire and see if you get spark by setting it against the block while cranking the motor. Then, while the plug is out run a compression check. Then if answer not there go ahead with checking valve lash etc. Start with fastest easiest test first and work your way up.

Always start diagnosing a problem with the easy stuff, if you don't then the problem will be the easy stuff, which will only be evident after you have pulled the engine and spent three weekends checking the hard stuff. Murphy lives.

[T77911S]

Originally Posted by austin552

With the motor running I wiggled the #3 wire connection at the cap to make sure it was connected. Got a nice shock through the boot. I will check the fuel to the cylinder tomorow.

Thanks guys

when i started to read this i thought, oh no, he didnt. he is playing with a loaded gun. i feel your pain.

do as said above. pull plug and check for spark at plug, do not hold the plug. then check compression. if all that is good you could just be way too rich on that cyl and you are fouling the plug.

you do have carbs right?

[hdbmw]

I just started reading the forums this weekend....always used Pelican for parts and reference...you guys are great on here! Doing the above should help you get to the "bottom" of what's going on with #3. Whatever you find since you refer to all your other plugs as "black", take the advise of the previous post and check the carbs. BTW docrodg, I have a pretty good machine shop I work with over here in CT when you need one in the future.

[austin552]

Well there was a spark with the plug. So I am getting air and fire. On to the fuel intake.

When I pushed the other accelerator pumps on my Zeniths I hear a spraying sound. When I pushed #3 there was no sound and the pump feels loose like its empty. I still have not removed the K&N filter base to try the paper test. Should I remove the linkage and that pump or what???

[docrodg]

do not disable the pump, it only give a squirt at the beginning. Just open the throttle a little then put the paper down there so if the pump is working it will have already squirted. I would say tho that if the pump has no fuel then you probably have a faulty carb.

[austin552]

No fuel reaches the barrel. the other pumps spray whenever I push them.

Pulled the banjos and the screens were clear. Pulled the 54, 52. There was fuel there and 52 opens and closes up and down. Think the back floats could be stuck or needs adjusting? I have a fuel level tool somewhere.

[austin552]

Float is stuck in the up position I believe. After removing the 54s and 52s I stuck a long narrow bolt gently down the hole and the float did not move. When I stuck it down the front hole the front float moved up and down. I will pull the top off the carb tomorow.

[BURN-BROS]

Glad it's not a huge problem.

[docrodg]

sounds right. I was thinking float, needle, or clogged pasagaes. Give it a good cleaning and rebuild and should be fine.

[T77911S]

glad to hear not a major problem.
if you are good with carbs, this may be a good time to take them off and soak them in carb cleaner and do a rebuild. i think the rebuild kit has new pump diaphrams which could also be the problem.

[austin552]

The carbs were rebuilt not that long ago.
Today I pulled the top off the carb and examined the float. All looked good. The gasket was hanging over the inside edge a bit so I trimmed that. Put the top back on and tested the float through the fuel inlet hole and no movement. The float was stuck in the bottom of the bowl. WEIRD I swapped the float for another I had in my parts stash and that did the trick. Put everything back together and fired her up. Runs allot better. Next I will dial everything in on the carbs and check the timing.
Whew!! What a relief...

Thanks guys,
Austin

[docrodg]

Great! Glad it worked!

[kidrock]

lotsa people helping out with some great suggestions, ending in success. God, I love this site.