Fuel Issue? Carb

[Jukes14]

Hey guys, I have a 1977 GMC C25 350 small block. I just had to get the truck towed from Aylmer to London, which is about a 35-40minute drive. Now the tow truck hauled it from the rear end of the truck, so the back up was up and the front wheels were riding on the ground. I noticed driving home from London to aylmer, that about 3/4 full pedal it started sputtering and back firing. Then in town it did it again, and actually died. My question is, do you guys think it being towed at that angle, shook up some rust or dirt in the tank? And possibly got into my lines? It doesn't appear there is a fuel filter anywhere. I have looked and cannot find one. My guess is that ride on the tow truck at such and angle shook up some rust or dirt possibly that was in the tank? Made it through the lines and now is making the carb not run right?

I've never had any issues before what so ever with it sputtering, or backfiring or anything. I feel that something is intermittently blocking fuel flow to the carb?

Any suggestions or insight would be much appreciated.

Among from that... the tow truck driver mashed in my driver side door really good trying to close it...... not having a good day

 

[1987 GMC Jimmy]

No, I don’t think debris in the tank would have migrated forward from towing it like that. Without using a rollback, that’s the best way to tow a RWD vehicle. Anyways, unless you had stuff already in the lines, that couldn’t happen. The pickup has a strainer sock on it, the lines enter the tank right at the top, and there was no suction coming from the fuel pump. It has a Quadrajet? Your filter is in the carb. You have to remove the line from the carb, and then behind that big bolt is where the filter lives. Be careful because the metal is soft, and there’s a spring in there. Also, I’m not discounting that there’s debris in the tank(s). That can overwhelm your strainer sock and cause starvation, as well. So can a failing fuel pump. A failing acc. pump diaphragm can also cause issues. Here are a few tests. First, I’d go ahead and replace the fuel filter and see if that fixes it. If it doesn’t run well or doesn’t start, look down the throat of the carb (I use the video camera on my phone and the light to make it easier), work the throttle, and you should see two streams of fuel on each side that begin the instant you move the throttle just a hair. Any lack of flow, weak streams, or drips indicate a problem there. Another test you can do is drop a piece of hose into a fuel can and hook it up to the pump to see if your issue is coming from behind the pump. It just splits your fuel system in half to help you discern which direction you need to go. You can also disconnect the steel line, turn the key to START, and put it in a 591 ml Coke bottle. It should fill up in about 8 seconds. If all you have are 500 ml bottles, you can adjust the time or bypass this step if you want. I’d also check for spark at some point just to make sure that the entire focus needs to be on the fuel system. By the way, what the hell kind of tow truck driver was that? Did they do any damage? I’d have his boss on the horn if he wasn’t self-employed.