The Stovebolt Site Forums The Parking Lot Big Bolts no start after welding

i am a major lurker here and have learned alot. i am in the process of putting a dump box on a 1950 6400. i got the truck from an old farmer, it had been sitting in his yard for 15 years. i have it running well but every time i weld on the box i can't get it to start. it cranks, but won't fire. if i give it a little shot of starting fluid it will eventually start and then run fine. am i doing something wrong or not doing something that i should before i weld. all i have been doing is unhooking the battery.

thanks, andy

Andy- Welcome! You will find lots of useful info here at this site, browse around and check the links page and check for parts/supply vendors. The first thing you need is a shop manual for your truck. It will pay for itself in just getting your truck up and running and everything adjusted properly. It sounds as if your truck has just been sitting for too many years. Don't know what you have done to it, or parts replaced. Old trucks that have been sitting need good battery, good spark and clean gas, for basics. Check your spark. Probably need new - spark plugs, points, condenser, distributor cap and rotor, plug wires. Also check fuel delivery. Make sure old gas in tank is completely drained and lines clear to fuel pump. New fuel filter, if so equipped. Open choke and move throttle shaft and check for fuel delivery . If no, then probable carburator problems like stuck float or plugged with varnish. If so rebuild carb and wash out with Gunk. Napa Auto parts will be able to help you there. Make sure your battery is new/fully charged and you have good connection. Toss old cables as they corrode under the insulation and usually become junk after several years. Starter should turn over easily and not smoke or spark. If so, replace or rebuild as necessary. All the info you will need to adjust carb, set timing, size type sparkplugs, etc, is in the shop manual. That's the best advise I can give you. Good Luck!

thanks chevyman, i have done all the things you suggested. all of which i did following instructions from this board. i do have a shop manaul for the truck and i rebuilt the carb, new points, condenser, cap, rotor, wires, plugs, coil, battery, battery cables, adjusted valves and it runs great. purrs like a kitten in fact, but whenever i weld on the dump box that i put on it, it won't start. it is a dump box like off of a regular dirt dump truck and is welded to the old rails that held the grain box so it is directly grounded to the truck frame and any time i strike an arc on the truck it refuses to start afterward, like its [censored] that i welded on it.

the whole story is, my wife and i bought a place next to a river to build a house. lots of sandpits in the area and we decided we wanted some ponds. i talked to a contractor and the price of digging with an excavator was just to high and required that we know where and how many ponds we wanteed. so, being a glutten for punishment, i bought a 1971 Insley excavator on e-bay. well ya can't dig for long and you end up with a huge pile of dirt next to your hole. i have a 1947 big bolt that my grandpa bought new in my shed, runs like it was new, but it has a grain box and dirt just don't come off a wood floor all that well and i refuse to change it from the way it was while i was growing up. so i steal this 1950 model from a guy that was a neighbor when i grew up on the farm. it was parked in his yard and he let me take it. took about two hours and pull to get it started. now after doing all that i mentioned above it runs great, i have the grain box off and the dirt box on. i left the frame portion of the grain box as it was welded to my truck frame and i figure it would be stronger this way anyway.

any one know why it won't start only if i weld on it?

andy

i read somewhere about the spark getting goofed up and having to be reset by grounding the voltage regulator, or something like that. as long as it starts, who cares??

i had the same experiance a few years back, and have had it on early mack trucks. all had a common trait. positive ground. i can't tell you why this occurs, but at 2 a.m. and ya want the thing to start on nothing happens, why don't mean much. on the mack the diodes in the alternator would fry, and on the g.m.c. gas job, the CONDENSER, AND THE CONDENSER ONLY fried. points, rotor, etc. are mechanical parts and could care less which way the current flows. capacitors, and diodes ain't quite that way.

for me the rule is to disconnect BOTH battery leads, and anything else connected to the battery. yeah i know, disconnecting 1 battery wire disconnects the system, but try removing them both and see what happens.

by the way, post the results will ya? things like this little mystery are the things that makes people go nuts and ya just may do a great service to us all.

oh yeah----------------stop yer lurking. get in here in the game with the rest of us. pics of your trucks are always welcome, as the opportunity to meet with, and maybe become friends with, another fellow bolter. i look forward to seeing more of your posts.

i will keep updating. may be awhile. someone broke into my shop last night and stold my lincoln arc and miller mig welders. they left all kinds of other stuff, but took all my welding gear. weird.

awier, sorry to hear about the break in. I've had my share of 'em and was so disgusted I wanted to just give up on all of my projects. I got over it and made my little garage a lot more secure. So far, so good.
About the tuck problem...the first thing that I thought of right away was the battery cable connections to the frame/transmission or starter. I know you said you've checked 'em, but next time, if you haven't done it, really clean 'em with wire brush, sandpaper or emery cloth. Wipe 'em down with a clean rag with a little thinner on it to get the oil or grease of and put di-electric grease, available at most parts houses on the mating surfaces of the connection. I hope that does the trick for you. I have a feeling that there's some type of electrolysis going on at these connections once you strike an arc.
Jacques

can't wait to get back at the old thing but it's only supposed to get up to 8 degrees here today. may have to wait.