Hello, I have a 1972 Buick Skylark convertible, 350, 5.7 liter, 2 barrel. It has run great all Summer and one day I took it out and drove just fine for about 10 minutes and then sputtered like it was not getting enough gas and misfired once or twice. I was able to spit and sputter at a very low speed to a nearby parking lot, where it ran for a bit with a really rough idle and then died when I tried to put it in drive. I got it back to my garage (via a very sketchy drive home at very low speeds and many restarts). I ended up replacing the carburetor, air filter, distributor cap and rotor, and all new spark plugs and wires. I was able to get It running again and it sounded great! I took it out for a drive and it sounded brand new, then after about 10 minutes, it sputtered at 50 mph and then backfired once and proceeded to turn off. I pulled over to the side of the road and kept trying to start it. Again, it seemed like it was not getting gas. I eventually cranked it enough times and pumped the gas and threw it into drive to spit and sputter to a nearby driveway. I had it towed home and now it sits. Any thoughts on what this may be? Fuel pump? I see no signs of any leaks anywhere, and the battery is still staying charged, so I don't think it's the alternator. I'm open to ideas. Thank you! Ben
Plugged fuel filter Failing fuel pump Rotted gas line jumper hose(s) Crud in gas tank Bad ignition coil That's a good start.
Fuel pump. Also could be a leaking hose, there is one at the drivers door could be leaking there or has a hole and sucking air. Take the line off the carb and crank the engine with the gas line in a can and see if you get gas and how much. If working properly you will pump a lot of gas out. so take the ignition wire off so the thing does not spark and start a fire. Take wire off coil from ignition system not the coil wire from the coil to distributor it will still spark on ground.
You need to inspect your entire fuel line. The pick up in the tank may be plugged, or a rubber line back near the tank may be rotted and sucking air. If the fuel pump is old, I would replace it just because they are cheap enough. https://www.rockauto.com/en/catalog...l+350cid+v8,1023028,fuel+&+air,fuel+pump,6256 https://www.rockauto.com/en/catalog...+v8,1023028,fuel+&+air,fuel+sending+unit,4436
Sort of Related.... My F250 was doing something like this several years ago. Tried everything I could think of then took it to a diesel repair shop. That shop said the high pressure injection pump was bad. Paid 1800.00 to have it replaced. Leaving the shop 20 min later it died again doing exactly the same thing. Sat for 10 mins and fired up only to die as I was pulling back into the same shop ready to pitch a bitch fit. I dropped the tank while there and found 2 filter / strainers attached to the pick up that were completely clogged. After it sat some of the crap fell off into the tank only to be picked back up while driving and starve out the fuel flow. The old plugged up sock on your factory pick up would do the same thing.
I had the same thing as Briz happen on our old Ford powered motorhome. The sock would get plugged up and the motor would be starved for fuel.
Not a bad idea to check out the fuel system, but always, always do the ignition first. A defective coil and condenser will act like that too.
Ignition related problems result in a very sudden stall in most cases. Sputtering is frequently fuel related. There can be exceptions to those generalities.
Great suggestions! I have changed the fuel pump and it still sounds terrible. I'm assuming I would need to remove the fuel and drop the tank in order to pull out the sending unit and look at the sock? Would you guys do this in your garage or take it to a shop? Can I do anything without taking the fuel tank off? I will double-check the hoses down the line as well. I will keep the ignition issues in mind, but it sure seems starved for fuel. I can spray some carb cleaner in the carburetor and it runs better temporarily. Thanks for the suggestions, I just need to determine if I attempt the fuel tank (carefully) at home or tow it to a shop. I'm open to ideas. Thanks!
It depends on the amount of fuel in the tank. It can be pretty heavy and awkward to handle if the tank is full. Taking the tank down is pretty easy. Maybe you can siphon fuel out of the tank if necessary. Have you checked point dwell, and vacuum?
I apologize, I'm an amateur learning to repair cars, so I will have to ask questions. What is point dwell? I know about vacuum leaks, but I'm not sure the best way to check for them. I'm always open to giving things a try. Thanks.
As originally built these cars use a tiny set of electrical breakers that ride on the distributer shaft. As the distributer turns these point come open and triggered the spark. Dwell is a measurement of this opening moment. A high quality timing light or dwell meter is used to adjust these via a screw. Google for lots more info.
No worries. Dwell angle is the amount of time, measured as degrees of rotation, that contact breakers close in a distributor. Unless dwell angle is accurate, ignition timing won't be accurate. The period, measured in degree of distributor cam rotation, during which the contact points remain closed is called the dwell angle. Dwell meters used to be a stand alone meter specifically for that purpose. Today, many good multi meters can measure dwell. The question is, does the engine still have points or has it been converted to electronic ignition? Vacuum gauges are not expensive, and they are a valuable diagnostic tool. On a stock engine, vacuum in a fully warm engine idling in Park should be 18-20" Hg. You can spray some carb cleaner around the mounting gasket. If you notice a difference, you have a cracked gasket, or the mounting bolts are loose. That will allow a vacuum leak and give you the symptoms you describe. I think that may in fact be your problem. A vacuum leak under the carburetor mounting will allow air that leans the mixture. Hesitation and stalling will result.
