I just got my truck back from a guy that put on my "new" old door, and repaired my A-pilliar. 52 GMC 228 with zenith carb: Now even before i took the truck in to this guy if i let it sit for longer then a couple of days i would sometimes have trouble getting it running. It would start up right away and run fine for a while. Then all of a sudden it would cut out, always under load. I would pull the choke out and it would kinda run if I pushed and pulled on the choke. I could take the small nut and screw out on the top of my carb. it would then run fine sometimes for 30+ min. Sometimes it would cut out again under load. Now that I have it back the problem is still there and seems to be getting worse. I can sometimes monkey around with it and it will all of a sudden run fine and it will run for as long as I like. It runs great and has great power. Oil pressure is 45psi + fully warmed up. Yes I love my G!!! Now I the problem is so intermittent. I am at a loss. I have rebuilt the carb, new fuel tank, pump. The plugs/wires/dist/points/coil are all new. Timing seems to be on. Seems to me to be something with the carb or some vacuum leak or something like that. Now short of trading in my carb for another zenith and throwing more money at it without knowing the problem, I just don't know what to do. I will look into taking it somewhere, but that will be tricky to do since most people or shops don't know what a carb is anymore. Any suggestions to what I can do to get this problem solved??? I dont mind taking it somewhere but I would like to get this fixed myself. This alone is what is keeping me from getting its licensed and taking it on the road. I can't wait so please help if ya can!!! Wolf
Wolf, I had a similar problem one time. I could remove the top of the carb, clean it out and put it back on and go for a little while before it would cut out and sometimes even leave me stranded. Finally, on one of my carb clean outs I noticed a very small amount of black material in the bottom of the bowl. I figured it was rubber from the connecting hose from the tank to the hard pipe. Sure enough, I replaced the hose and the problem was solved. I don't know if this is your problem but, if you did not replace them before now, it is worth trying. Good luck, Gater
actually that sounds very very similar to what i am experiencing. I will take the top of the carb off and :"clean" it out and it will run great. But the strange thing is that i never find anything in there?!?!? I have actually replaced all the hoses associated with the fuel system. That could be good though... could point to the carb anyway? maybe? heck i don't know? I will replace the hoses again however.
I used to get the fine black sludge, and I could field dress y carb on the roadside in no time. I put in a new tank, lines, hoses, engine, and now I don't have that problem. Check in your gas tank, it sits in the bottom. Flush your lines and tank, see if it helps. That mess gets past the filters.
Wolf AS others indicate, it seems to be related to the fuel system. Years back (30 or so), My fathers 56 chevy work truck had similar problems with the engine cutting out and dying, moslty under load. The truck had a resister that was on the firewall, wired between the hot lead and coil. When the resister heated up itbroke the circuit - causing the engine to cut out and/or misfire. We replaced it and no problem afterwards. The truck is long gone. Howard
The capacator may be going bad. A fuel filter would catch trash that would plug the carb. The ceramic resistor acts that way also. IIRC there is a coil that does not need the ceramic resistor it has 3 ohms resistance built in. If the carb is clean it is probably the capacator, which I have been told makes the points pit, or the ceramic resistor. If the resistor is bad, a visual inspection may find a flaw. At least both are cheap!
ol chebby: I know exactly what you are talking about. I am getting good about taking the top of the carb off on the roadside... The crazy thing is is that I never have found anything in there??? Never any of that black stuff you guys talk about. My carb is always clean, but when i "clean" it out or at least take off the top of the carb and mess with it, it will then run great.. sometimes. Every time I have to do this i flush out the fuel lines also. Sometimes I get junk out, but most of the time I don't. But none of this junk makes it past the filter and I check the filter also every time too... I will also recheck the coil and resistor. I replaced these recently, but you never know. The crazy thing is that it doesn't do it all the time. If i can get it running good for say 2 min straight, it will run for as long as I want it to. Driven it 45 min plus a couple of times and it ran great. Will do some checking with the ignition hopefully tonight and get back to you. The only part of the fuel system that is not new are the fuel lines. I'm thinking that I need to address these soon. All the fuel hoses are new as well as the tank
Poor Running Wolf ; how it runs poorly will give you a better idea of where to look . If the condensor is going bad (yes , I've had many bad new ones) the engine will buck and sputter as if the spark is cutting out and throttle changes won't affect it much if any , it'll run *perfectly* when you first start it up but wil get progrseeively worse as you drive , try letting it sit sans dist. cap for 10 minutes and see if it <magically> runs great for a few minutes again .. Look in your junk box (or under the seat) and grab any old nasty condensor you find and try it ~ if it works , they you've found the culprit . (old timey roadside fix for bum condensor: dent it with pliers , if it now makes good sparks , head for the nearest FLAPS and buy another one) Is this truck still 6 volts ? . if so , there's no resistor . It's 12 volts ? okay , it *might* have/need a resistor but only if the starter has a by pass circuit connected to it (extra thin wire not on the battery terminal) . some folks don't understand how ballast resistors work and so add them to any 6 > 12 volt comversion where they age and cause greif . I hope this helps , read lots about this in older posts .
i will try to inspect the resistor soon. my truck is now a 12 neg ground electrical system. prior if you remember the GMC's were 6 volt + ground systems. the problem definitly seems more fuel related. I am going to replace my steel lines with new ss ones. that is the only part of the fuel system that is not new. and i do get some junk out of the lines when i pull the filter off and put the line in an old beer / soda can and crank the engine over. i have never had any junk up in the carb. I may just get a coil from napa with the internal resistor anyways.
12 Volt Ign. Coils O.K. , if you look in older posts , I posted the correct PN for the Epoxy filled coil from NAPA.... It is _vital_ for you to test it across the posts before installing it for the correct impedance .
Any luck yet? I guess this means I shouldn't look for you to be rolling in here anytime soon? Hang in there with it. One thing you know it's not, is a problem with the computer! Pictures of it with its new door?
yep no luck with it yet. i have been out of town for bout a week now. Went up to iowa for a proposal for my job for 2 days, then took a trip back to north west kansas to hang out with my family. Got a ton of stuff done for my parents. wired an entire garage, lots of yard work, and house work, and put in a lot... a lot of fence. But good news is my truck is still there waiting for me!!! I will go get the new fuel lines tommorow, but i will be at my wifes parents house this weekend, so i hope to get to it soon. Paul I will get some pics posted soon of the progress thus far. Looks good to have a back window and a passenger door!!! Ol chebby: Thanks for the part number from napa for the 12volt internal resister coil!!!
update Well ok an update: I have installed all new fuel lines SS type. The truck ran great that evening. The next day I took it out and it sputtered and tried to die, but i just pulled the choke for a few seconds in and out and it kept on running. Then next day took it out and it seemed to be back to its old sputtering ways. Now last night tried to drive it and it starts sputtering so i just parked it. Now I am completely at a loss. Very frustrated as well. I am thinking it has to do with the carb, due to the fact that it is an intermittent problem, and when I pull the choke out it will run a little better and I have to push/pull the choke in/out for a little while until it gets out of its "funk" then it could run fine for a bit or it will just keep doing this. But if it dies, I pull the choke out and it starts right back up. Any other suggestions??? Im looking into a different rebuilt zenith carb, but don't want to loose 175 bucks if its not that. Have already rebuilt the carb once. Would the coil or ignition cause this problem to be intermittent as well? If so what would it run or keep running when i pull the choke out?
Fuel delivery This sure sounds like a fuel delivery problem. Either a hole in your fuel pump diaphragm (need to repair or replace) or the filter being clogged...
I use a gallon can with an electric fuel pump mounted on it. On the outlet hose I can use whatever fitting the carb takes. This set up eliminates everything BUT the carburetor. If it acts up it is the carb and if it doesn't it's some other part of the fuel system. Also have a HEI distributor off a late 70's 250 six that has the housing modified to fully engage the 216/235 oil pump to see what's up if ignition may be the problem. The HEI is a stand alone ignition that just takes a 12v wire to operate. If this cures what's ailing one then I work my way back through coil, condensor, resistor, etc. Saves alot of guess work.
What Evan Said ! This really sounds like a fuel delivery or vacuum leak issue to me ~ both will get better if you pull the choke out . One way to test is to duct tape a 1 gallon steel can to the roof and run a hose down to the carby , no fuel pump needed once you suck on the hose and get the siphon going ~ you don't want to know how many states I've crossed with this setup getting some old junker home .
I will have to try that... roof rack... and the fuel tank thing. I don't want to think that my fuel pump is no good, its brand new! Also why would it run great sometimes and not the others? Do fuel pumps fail like that?? Also the fuel filter is new. I can easily blow through it. I just don't know what to think anymore If it were a vacuum leak where bouts would it be most likely? Keep in mind I do have the GMC 228 with zenith carb if that makes a difference. Thanks to all for the help, I don't know what I would do without you guys Nate I would love to see you driving something like that home!!! Evan: would that ignition work with the GMC engine?? I haven't ruled out the ignition yet
Auxilliary Fuel Tanks Well ; Some years back I was wheezing a dilapidated IHC school bus with a two axle trailer loaded with my old '53 MGTD on it across America , and in Colorado the second fuel pump failed in the mountains on a narrow road in the middle of a blind curve . While my then young son was off playing with the wild deer , I decided I'd had enough B.S. with crappy fuel pumps and rigged an old gallon jug to the right West Coaster Mirror and drove the rig on home like that.... Ya gotta do what ya gotta do . I'd look for vacuum leaks in the phenolic heat insulator thingie between the carby and the intake manifold , the original ones were Bakelite and loved getting tiny cracks but only in summer and when you were far from tools . Then I'd check the intake manifold to cylinder head joints , remembering to check _underneath_ each joint too as that's where my '49s 235 has troubles . Putting the fuel supply on the roof just eliminates the rest of the fuel system from faults ~ pump , tank and lines . If it <magically) begins to run O.K. , then you know where not to look .
