Popping/backfiring

[Overthedge21]

I recently bought a 1987 chevy k10 with the 350 tbi. I just got it registered yesterday, and drove it more than ten feet for the first time today. It had run fine in my driveway every time i ran it over the past two weeks. I bought a few gallons of gas before I tried to drive it because the gauge read empty. After putting that in, and checking the radiator was still full (previous owner had let coolant levels fall extremely low), I started driving it. After about a minute or less, I noticed that when given gas it would pop and backfire randomly, which it had never done before, and I had run it for 5 to ten minutes in my driveway in the previous days, and it had never done this, warm or cold. The temp gauge read that it was overheating, although I am not sure it is correct, as it reads around 210-230 degrees after only two or three minutes of running, and even when it reads that, the block is still touchable as is the radiator and neither of them feel that hot. It only pops and backfired after it got hot, as in over 210 degrees according to the gauge. Also, it only popped when given gas. At idle while rolling it sounded fine. My question is, is the truck actually overheating, or was it running out of fuel, or is there a different issue altogether? Also as a sidnote, i test drove it before I had bought it, when it was very low on all fluids, and it did not do this, even after warming up. It doesn't smoke or burn any fluids.

 

[1987 GMC Jimmy]

I recently bought a 1987 chevy k10 with the 350 tbi. I just got it registered yesterday, and drove it more than ten feet for the first time today. It had run fine in my driveway every time i ran it over the past two weeks. I bought a few gallons of gas before I tried to drive it because the gauge read empty. After putting that in, and checking the radiator was still full (previous owner had let coolant levels fall extremely low), I started driving it. After about a minute or less, I noticed that when given gas it would pop and backfire randomly, which it had never done before, and I had run it for 5 to ten minutes in my driveway in the previous days, and it had never done this, warm or cold. The temp gauge read that it was overheating, although I am not sure it is correct, as it reads around 210-230 degrees after only two or three minutes of running, and even when it reads that, the block is still touchable as is the radiator and neither of them feel that hot. It only pops and backfired after it got hot, as in over 210 degrees according to the gauge. Also, it only popped when given gas. At idle while rolling it sounded fine. My question is, is the truck actually overheating, or was it running out of fuel, or is there a different issue altogether? Also as a sidnote, i test drove it before I had bought it, when it was very low on all fluids, and it did not do this, even after warming up. It doesn't smoke or burn any fluids.

Several things here for me. You need to get that temperature to 195-200. You need to flush your coolant because it sounds like that was abused. You'll probably also need to replace your thermostat because it may be sticking closed. See where that gets you with the temperature because you're not necessarily overheating, but you're running hot. You don't want that come summer. If you have a Harbor Freight near you, get you a non-contact thermometer so you can compare it to your dash gauge and check it while you're under the hood. If you don't have a timing light, it may be a good idea to get one. I'm willing to bet the timing is not where it needs to be. It would like 4-8* BTDC. See if you can get it to 8 without pinging. Are you getting a Service Engine Soon light when you turn the key on? Have you tried to pull codes by jumping the two top right pins on the ALDL with a paperclip and counting the flashes? You should try that because when my ECM went bad, it did what yours is doing. You need to replace your fuel filter and make sure you're getting clean fuel. See where you find yourself after doing and checking those things. You need to run cooler with clean fuel, good timing, and good ECM feedback. Wouldn't hurt to put some more gas. If it hasn't already, you don't want to suck gas from the bottom to risk inundating the strainer sock(s) with debris.