View Full Version : Carb Backfires

08-23-2001, 10:00 PM
Well, here's the jist of what has gone on in the past day or two. First, I got it running tuesday with a bad cough from the carb. It would spit crap back up through the carb at me. I rebuilt it today after I got three carbs from Taz and used one for parts. I rebuilt it at about 3 pm. Went to work, came home at around 7:15. Started working on it. It finally turned over and caught and ran ok. About a minute after it was going, the carb backfired twice and then all hell broke loose. The carb caught fire and so did the manifold. I called 911 and tried to douse the flames with a bucket of water. I finally got the flames out with a cooler full of water. Once I got it out, the fire department got there. They told me that I had to do something with it but it couldn't keep it there. I called Taz and he offered to give me a hand with it or buy it. What caused it to backfire? Keep in mind that I haven't timed it yet and it will need a valve job. I also noticed that there was a half an inch of gas in the manifold. Can any one help? I will get a new carb soon.


08-24-2001, 12:27 AM
Hey, I think that correct timing is the key. Now I don't know what engine you have, but any one of these other guys on here could probably tell you what to set your timing at. I have a brand new GM 350 in my van and it was having trouble starting and also backfiring through the carb. Now I had set the timing once before, but sure enough, it was off quite a bit. I reset it to its proper mark and now I barely have to turn the key and it cranks right over. I really don't think your valves have any thing to do with the backfiring but I guess there's always that possibility that air/fuel could pass back through a valve thats not completely closing. But then you'd think that it wouldn't run well anyway. So good luck and don't let your dad scrap that old van. I think it's cool that there are young kids out there who love these things as much as the rest of us.


08-24-2001, 02:17 PM

Timing is a major key with back fire problems. Altough when you rebuilt the carb you really needed (if you didn't) get a kit from say NAPA or another parts store. the reason for the kit, is that it will have a lot of new parts that you have to replace upon rebuild. Before you try to start the van again check to see if your float level is the right height. If its not that will flood the bowl in the carb, and than into the intake. Next, check your idle mixture screw. Give it the proper number of turns. Hope this helps.


08-24-2001, 09:23 PM
tony you may want to run an extra fuel filter(inline) to the carb.i'm not sure how much run time this vans got but if your pumping dirty fuel thru the carb this will contaminate your carb and cause your needle not to seat right.thus causing a flooded carb that you just spent alot of time rebuilding.if it is flooding as it seems it is you'll need to pull your float and its needle out and blow out your carb with carb cleaner.heres a question by turning the float adjustment screw clockwise are you able to change the fuel level in the float bowl if not perform the above.your float needle is either dirty or defective.you should be able to adjust this level to where the fuel is just dripping out of the sight hole on the float bowl.if this is working right you may have a problem with your idle mixture screws having dirt in them.remove the mixture screws and blow out the passage with carb cleaner.reinsert screws and turn them in fully clockwise till it bottoms out.don't tighten to hard just snug.turn out (counterclockwise 2 turns.)this is a good starting point.the other two items often overlooked are is your throttle fully releasing when gas pedal not pushed.their should be no throttle input at idle.make sure that the idle speed screw is not set to high.always start with little to no input or you could flood the carb.the last but usually the most common problem is your choke is not set right.with the engine cold check to see that it moves freely and you must set it to about 1/16 of an inch gap closed.(cold gap)if you do the above you should be able to get that baby running and be able to slowly dial it in.refer to a service manual if you don't follow along.backfiring is usualy a result of a misadjusted carb or an incorrect timing.but the bottom line if your carb's running right it should be adjustable with the adjustment screws if not its either dirt,a defective carb part,choke or to high of fuel pressure(defective fuel pump).eliminate each of these and you will find your problem.good luck and take care tom.don't forget to put that air cleaner on it will keep away the fire dept just in case it does still backfire.

08-24-2001, 09:41 PM
?????since when did firemen become cops?any vehicle with a gas tank could be a potential accident.what gives them the right to tell tony to move his van?!?!?!
until a REAL county worker with a ligitimite reason comes by your house thares NO REASON IN THE WORLD to move that van.
im not shure what state you live in tony,but can you get historic tags or an inspection waiver if your vans not taged?
remember,thares ALWAYS a way around a problem.you dont live in RUSSIA you live in the USA!!!!!!! were ALOWED to own vans....weather they catch fire or not : )
dont let the minor frustrations get you down
keep your van,keep on working on it and if worse comes to worse you can use my P.O.box in west virginia to get some tags and thare wont be a thing your state can do about it for 6 months

08-24-2001, 11:42 PM
I live in Illinois. There is no vehicle inspection besides the emissions test. It is a federal test applying to cars built in 68 and up. My car would never pass any inspection in any other state. I just said F*** the old carb, I might get a new one if you can convince my father that I should keep it.