The Stovebolt Site Forums The Shop Area Engine Shop Why its not starting? list.....

This is just another thread of me trying to get my 51 GMC Maple Leaf to start.

What i have:
- Spark
- TDC
- Ignition timing set
- 1/4 tank of new gas
- fuel getting to the carb, but not filling the float bowl.
- 1 gauge battery cables
- a starter that smokes if ii step on the starter for more than 10 seconds at a time
- New AC Delco R45 spark plugs
- New wires
- Had a new distributor cap and rotor but was sent the wrong ones
- new condenser
- new points
- new coil
- new oil
- probably a stuck cylinder # 3 or 6... or both

What am i missing that is causing her not to start??


Im out of ideas, other than maybe the spark plugs aren't generation a hot enough spark, but even so, i have no fuel in the float bowl...

no point in going further than no fuel in the bowl, sure won't start like that ....
fual pump weak? disconnect line from carb and point it into a can and see how much it pumps - if the engine is turning slowly it likely won't be pumping strongly, try with all the plugs out ....
carb inlet plugged? needle seat stuck in inlet? float set way wrong? check over the carb well

"probably a stuck cylinder # 3 or 6... or both"
what's that mean? how can the engine crank if it has a "stuck cylinder"?? if something is binding [rusty cylinder walls or stuck/dragging valves] that accounts for the starter smoking, it's working too hard .... if you've tried cranking it with all the plugs out and it still cranks slowly and smokes the starter, there's no point in trying to start it at all, find out what's wrong

Bill

If you have fuel pressure at the carb and no fuel in the carb, your needle valve could be stuck or you have trash in your carb inlet. If its a Zenith, it could have a filter thats plugged.

If your starter smokes, it must be dragging and its sucking all the current from your ignition. You need to rebuild it or buy a rebuilt.

The reason i think my stater smokes is because ive been standing on the starter longer than i should have, in hopes of the engine actually starting.
When i say i think i have a stuck cylinder, i dont mean like stuck solid. just a real tough spot when truning the engine by hand.
The carb is a rochester b1... ill see if the carb inlet is plugged... but i am currently looking for a good rebuild kit, know a place that has a good one?
any other suggestions?

The truck has sat for a while. Chances are your gas tank has plenty of rust and varnish in it. If the truck was stored with gas in the tank, that gas went bad a long time ago and turned into varnish. Putting new gas in the tank will dissolve the varnish and move it into the engine where it can cause many more problems with the carb and valves.

Replace the fuel line from the fuel pump to the carbuerator. (you can use a flexible fuel rated rubber hose for a temporary fix) Remove and plug the fuel line that feeds the fuel pump.

You can run a temporary fuel line from a portable gas can to the fuel pump.

Note: Carbuerators do not like to sit for 20 plus years
Note: Carbureators do not like rust or varnish in the tank
Note: The carburetor will need to be taken apart and rebuilt, or replaced with a good carberator.

As stated in earlier threads, A compression test is necessary at this time to determine weather or not the engine will start.

The good news... the engine turns over, you do not have stuck cylinders.

The bad news... the engine has sat for several decades. It may not have ran when parked.

More bad news, trying to start the engine without cleaning the gas tank and lines may have wrecked your carb. If some of that dirty gas got into your engine, the varnish may stick some valves and bend some pushrods

Your engine could start even with a bad carb and fuel pump if you poor a couple teaspoons of gas directly down the throat of the carb.

OK, one more dumb question, when you are trying to start your truck, Do you have the ignition switch on, and does it work? The truck will crank over for a long time without starting if your ignition switch is off.

All good question above, I can add a few.

Does it try to fire if you dump a little fuel down the carb?

Are the plugs even firing? pull one out and lay it across the engine to check.

Is the starter really hot? or just burning grease and oil out of it?

Have you pulled the plugs and spun it over with oil in the cylinders using a 12 volt battery?

Do the rocker arms have oil up to them?

Have you tried a small fuel jug instead of the fuel tank?

Have you rebuilt the carb? Its a must for a old engine!

Joe

Bigbadswingdaddy: I drained the fuel tank and lines before i even attempted to start the engine, i also filled the tank up again and re drained that. so im pretty sure any varnish in the tank should be gone.
I've taken apart the carb and noticed it was rebuilt sometime before the truck was park, it had a lot newer materials in it than what a stock carb would have had at the time. im looking into a rebuilt kit but haven found one yet.
i keep meaning to borrow my shop's compression tester but yet again i forgot to grab it before the weekend.
And yes, i have the ignition switch on and it does work, the second i turn the key my fuel gauge goes up to about 1/4 tank of gas.

Joe H: I wouldn't say she fires when i dump fuel down the carb, but she sputters.
how would i check if the plugs are firing?? i have spark when i hold them right against the hole for the plugs....
the starter gets really hot if i stay on the floor start for more then 7 seconds, maybe 6 times in a row.
yes ive hooked a 12v battery up to it and she spins real fast.
Rocker arms have oil.
no i havent tried a small fuel jug and again, im looking for a rebuild kit for my carb....

Sounds like you have the bases covered. If it sputters with fuel dumped in it, then its firing. I wouldn't worry about compression just yet. Pull the valve cover if you haven't all ready and recheck the valve adjustment. Just a simple wiggle test on 12 as you rotate the engine. None should be supper loose or tight. When on the base circle of the cam and both valves shut, you should have zero lash if hydraulic lifters, and some lash if solid lifters.

Get the carb cleaned up and working. The needle and seat needs so attention if the float bowl is still empty after all you cranking.

Reread the posts on timing and figure out which way to retard it. Go a little at a time and see what happens. To much advance will kick back and cause a hard start.

Something else to try is a spray bottle with fuel in it. As someone cranks the starter, spray a mist of fuel down the carb
Keep your head and hands back incase of backfire. This helps if you are unsure of the carbs working condition.

Good luck to you, Joe

Thanks joe, I'll give the spray bottle a try once i get my rebuild kit... i've taken my carb apart completely and it looks as if theres like calcium build up (not literally, just what it looks like).

In the mean time, I'm going to pour some diesel fuel into the spark plug holes and let the sit for a couple days, just to try and loosen things up (any rusted walls ect).
But do i drain the oil completely before i pour diesel into it, or just go ahead and pour it in with the oil still in the engine?

I would pour in some oil, that way you don't have to drain the crank case. Be sure and blow it out with the starter before trying to start engine. To much oil can foul out a plug pretty cast.