1972 GMC 350 quad not starting
 

It started fine has a miss but after turning it off and removing the dist. cap it turns over but wont start. All I did was remove the rotor.cap and checked the points buttoned it back together and now have a truck that wont start.I am all of a sudden thinking fuel pump. I can look into the front of the carb while moving the throttle and see gas coming out the right side front barrel but none from the left. I took the line loose into the carb and ran ran the open end into a bottle and gas comes out but not sure if its enough. I did put a new filter in not long ago. Any ideas as to why a sudden not start.

Re: 1972 GMC 350 quad not starting
 

Did you put the rotor back on? If so, did you seat it correctly?

Not being a smart a$$. I have forgot the rotor before and was pi$$ed. Then I noticed the rotor in the hand of the better half as she was looking at me shaking her head.

Re: 1972 GMC 350 quad not starting
 

Rotor is on and I have left it off a time or two also. Only thing I did was opened the points a little just to see if they were burned any and slid a piece of business card through to clean them off.Seems it not even trying to start but after sitting 3 days it fired right up then shut it down after a couple minutes before removing anything.

Re: 1972 GMC 350 quad not starting
 

Sliding a business card between them won't clean them. Using the "striker" strip on the back of a matchbook will clean them a tad. use the business card to set the gap. ;)

Gary

Re: 1972 GMC 350 quad not starting
 

I have the truck since 81 never had a similar problem but anything can happen and eventually will. It has to be something with my removal of the cap and rotor since it ran before with a miss. SHould gas be coming from both sides of the carb when I open the throttle by hand looking into it.Only the drivers side has gas spewing out. I am pulling the cap and rotor again in the morning for the third time just see if I missed something.

Re: 1972 GMC 350 quad not starting
 

You could put an hei in there quite easy,idk how dead set you are on keeping it originally equipped.

Re: 1972 GMC 350 quad not starting
 

Is it possible you may have broken a wire to the distributor (not a spark plug wire) while leaning over the engine?

Pull a plug wire and hook it to a spark plug laying on the engine and check that the plugs are getting spark when turned over to eliminate anything you did.

Re: 1972 GMC 350 quad not starting
 

Thanks ,that is a great possibility and will definitely check that out this morning and hope that is it.
Seems more likely something I did since it ran started just before and never really changed anything. I will get back will any results. Thanks a million.

Re: 1972 GMC 350 quad not starting
 

pull the coil wire off the cap and check for spark. If you have bright spark I'd look at the points. How old are they? Did you set them static or use a timing light? Static works fine if points are resting on highest spot on shaft AND the nylon wear surface isn't worn down a lot. If not getting good spark, before you run out for a coil, check the coil wires.

If you are getting any gas at all the engine should kick over some. If it's just cranking it could be fuel. Pull the line loose from the carb and have someone crank it real short while you hold a rag over the end or a cup to catch fuel. It should belch out pretty good. But, again, any at all will make the engine want to kick and try to start.

Re: 1972 GMC 350 quad not starting
 

I checked the coil as you said special k with no fire at all. Tried a known good coil still no fire. Changes coil wire with known good wire still no fire. Have removed the cap again checked wires everything looks ok as far as I can tell but something is not getting it.I did not change points just checked them now I am afraid to do anything after just removing the caps and rotor and end up with a truck that wont crank. Anything else to check for why I have no spark, Rotor turns and all but something happened when I removed the cap to cause this I am positive.I do remember years ago removing the points adding new ones had had a no crank and putting the old back in it was fine. Only thing I did was open the points with a screw driver just to take a closer look.Thanks for any help

Re: 1972 GMC 350 quad not starting
 

I checked power to both terminals with switch on on coil and have 15 volts which I think is way too high.I am charging the battery that may have some say on the high voltage.I also found out after reading numerous thread it seems the two wire on the coil have been hooked up wrong forever. Does the yellow wire from starter connect to negative and black from dist. to positive. Mine has been and still is.

Re: 1972 GMC 350 quad not starting
 

It's possible the battery has a high surface charge. You can turn your headlights on for a few minutes, then recheck battery voltage. That should have burned off the surface charge. I highly doubt too much voltage is the no start issue, but it certainly can burn up electrical components.

Re: 1972 GMC 350 quad not starting
 

Another question while working on this thing starting. Does the wire from the dist. mine is black connect to the positive side mine is.

Re: 1972 GMC 350 quad not starting
 

Took the dis. cap back off and opened the plug gap up a tad more and it actually finally cranked and ran fro a few minutes very rough until I shut it down. It did't want to crank again. Tried to set the plug gap with the dwell meter but couldn't get it cranked back up.Still not sure where the fixies though. Gonna try again today . Any more suggestions.

Re: 1972 GMC 350 quad not starting
 

Just a guess. Could be intermittent condensor, either it's about shot or the wire is worn type thing. Before you messed with the points initially, did you notice if contacts were blued at all? I can't read through right now but, if you haven't already, go get at least new points & condensor and try that. Also, while you're at it, check how tight the distributor shaft is for wobble.

Re: 1972 GMC 350 quad not starting
 

I did not notice about the points being blue or not. I do need to check that shaft though because one thing I did notice was when I set the old points and turned the engine over to a different lobe the points were off a bit. As soon as the rain yields a little back out to check it out.Points and condenser next I guess and new dist. cap.I was just glad it ran rough but still ran. Thanks again for the help and will get back soon.

Re: 1972 GMC 350 quad not starting
 

What is the gap set at? Fairly wide? If you don't have feeler gauges you should get a set. You would have to have the points set really wide or close for dist shaft wobble to keep it from firing. Could it be they are set too wide or too tight?

Re: 1972 GMC 350 quad not starting
 

Ok finally solved and first I want to thank you all for your help and input I love coming on here and getting extra help it is never too much. Special K I replaced the points and condenser as you said and that did it after I uncrossed 2 wires and set the dwell at 34 and ran it for 5 minutes it runs better than ever and fires up right off the bat . I set the gap with the credit card but must have been way off cause I used the dwell meter and it showed about 25 so I got it corrected.I was getting ready to get another coil but that can wait. I had o fire at the plugs . Never knew the points or and condenser played that much of a role in getting spark but it does. I hope this being solved can help someone else in the future and thank again for the quick responses and help I really appreciate it very much.

Re: 1972 GMC 350 quad not starting
 

As far as wires to the coil , there is a white cloth covered wire from the fuse block to the coil positive , its a resistor wire and should read around 9 volts at the coil with the key on , there is another wire from the coil positive that runs to the starter , it is full voltage only while cranking

Re: 1972 GMC 350 quad not starting
 

[QUOTE=tk1251k;7413890]Never knew the points or and condenser played that much of a role in getting spark but it does.QUOTE]

The points and condenser are crucial to getting any spark in a points system. It's great you got it figured out, and now you've got more knowledge for your toolbox. Thanks for the update, we don't get a lot of that around here and it's so helpful for others.

:metal:

Re: 1972 GMC 350 quad not starting
 

Thanks for your answer. I noticed after reading through many threads mine must be on reversed.I have a yellow wire that branches off on the firewall and one runs to the starter from the negative post and the black wire runs to the distributor. Not sure it matters or not but must have been this way for a very long time.I have had the truck since 81 and think the coil was changed once. I guess I need to reverse them back anyone think different.