1968 GM 292 straight six engine not firing HELP??

[Renni O.]

Me and a buddy are trying to repair my father's 1968 GMC 1/2 ton pickup with a 292 straight six engine that just recently ran fine but now, won't fire. So far, we have replaced the distibutor cap, points, rotor and condenser. We also have correctly gapped the points and the firing order from cap to plug is correct. The coil and wire is in working order (as my friend almost juiced himself through the hood while testing for coil spark to the cap as I turned it over lol) the timing has also not been disturbed since vehicle last ran fine. We have also changed both fuel filters and the carburetor was just rebuilt 2 years ago (profesionally) and it is getting gas so fuel pump is fine. We both agree that even if timing was slightly off it should at least "try" to fire but we can crank it forever and it won't even try to fire. If anyone has any ideas please reply here or send me an e-mail @ americanjedi77@yahoo.com ANY HELP WOULD BE GREATLY APPRECIATED THANK YOU!!
 

[Renni O.]

P.S. the spark plugs are also in good looking shape (and not that old) but we are just getting no spark from the plug wires,..just don"t know what to do here. =(
 

[ericlb]

ok renni, your saying the truck ran before you worked on it? ok first 2 things to check, 1 you might have accidently grounded the wire that attaches to the nut on the points, check very carefully, this is the most likely problem, 2 look at the rotor, is it exactly the same as the one that was on the truck? both top and the size of the hole in the bottom, then when you installed the new cap did you put in the little button and spring thing where the rotor rubs it in the center of the cap? and if you did is the rotor in fact touching it with the cap on the distributor, check these things and post back with what you find, it will be something simple
 

[Jobreated59]

try putting the old condenser back in-sometimes you get bad parts
 

[DaveS]

If you are getting spark out of the coil but not out of the spark plugs, you have a bad rotor.... And yes you can have a bad one even if it is new.
 

[Renni O.]

O.K., my bad the truck is getting spark (to the plugs) and it's getting fuel but still won't fire. My buddy suggested that the voltage regulator may be fried,..thoughts??
 

[cole in mo.]

Forget the voltage reg, pull the plugs and squirt a little oil in each cyl, replace the plugs and try it.
 

[Kentb of SWMO]

Voltage regulator has NOTHING to do with making the engine run. It's ONLY job, once the engine is running, is to control the charge rate of the generator/alternator into the battery.

Kent
 

[Brother Dave]

You may want to check the distributor shaft side to side for play. Grab the rotor button and move north to south and east to west, it should be tight. If you do feel a good bit of play it could change your opening and closeing of the points. You said the fireing order was O.K. 1-5,3-6,2-4. Did you check the rotation of the rotary button to verify the rotation of the distributor? I also agree that some of the internal wire to the distributor could be grounding.
To check the new condensor without an ohm meter, remove the condensor and stick the wire end into the end of a spark plug wire on a good engine. Start the engine and hold the condensor clsoe to the block or a plug, a strong spark should jump. If it doesn"t the condensor is bad. NOTE: Be sure to short the condensor houseing and the lead wire with a screwdriver before you handle it. That stored energy will rattle your teeth if you complete the circuit with you hand. You may need to check the fuel bowl in the carb. Old gas or water can make a glob in the fuel bowl and give a person fits when trying to start a truck. Also on some models, GM used a fiber type float that would get spongy over time and cause a problem with the carb. The last thing to check would be the negative battery cable. On some of the older model trucks the wires at the block will fatigue and break and leave only a few to connect the block to the battery. If it gets fire, is reasonably in time, and is getting fuel, it should start.
 

[ericlb]

renni i was gone awhile, is your truck running? if not,in your bottom post you said your getting fire to the plugs but it wont start, only 2 things can be happening here, gas fouled plugs[ replace plugs] now when you put the new cap on how did you move the wires from the old cap to the new one? 1 at a time or all at once? check the firing order of the wires bring the engine up to top dead center on the number one cylinder, the easiest way is to remove the plug on that cylinder and have your buddy tap the starter, with the key, this will just barely move the engine untill you feel air pressure at the plug hole, then turn the engine by hand untill the timing mark on the crankshaft pully lines up with the mark on the front cover, now note the position of the wire to number one cylinder, remove the dist cap the rotor should be pointing at that terminal under the cap, withthat right, follow the firing order around in the same rotation as the distrubutor goes, [ bump the engine over to see which way] and make sure your wires and the firing order of the engine, [ cast into the top of the intake manifold] match, then if thats right and the plugs are new it should start
 

[offeritup]

IF you are getting fire to the plugs, are you getting it to all of them? I'vehad caps thatwe so off center that only a couple plugs would hit. I'm assuming that if you pull the cap the rotor spins when you crank the engine.

A quick timing check - pull the plugs, turn the engine until you can see the top of the piston thru the front plug hole, the distritbutor rotor should point at that plug wire or the one opposite.

You did get the wires on the cap in the correct location (position and order), right? (that's my favorite mistake)