The Stovebolt Site Forums The Shop Area Engine Shop 1950 Chevy is cutting out

I am hoping someone can help.

At first the 1950 Chevy pickup started running fine after warming up a 5 mile stretch she would start cutting out. Then totally lose power. This is a 235 engine in case anyone needs to know. So last night replace the following: fuel lines, fuel pump, fuel filter, battery. Have a Rochester Carb can not find specs on to see if it is set up right.

Thought I had problem taking care of when I went out for another run and then she did it again. Now have been working on carb and I can not get it to start unless I ether it or when I do get it started it won't stay running. Had wife inside starting it and notice no fuel coming to carb now. These lines that I have on now are the metal ones that I switched back to from the new rubber ones thinking this would cure my problem (I was thinking vapor lock). :mad:

Any help would be appreciated.

You need to do a pressure/vacuum check of the fuel pump. Even a new pump could have problems, but I think I know where this situation is going. Start by giving the carb an independent fuel supply, like a 1-gallon can with a piece of copper tubing soldered into it, hung from the hood somewhere above the carb. Gravity flow will give you enough gas to idle, at least.

A good fuel pump will develop 3 to 5 pounds of pressure at the outlet line, and hold it for a few seconds after the engine is shut down. Then go to the inlet side, attach a vacuum gauge, and idle the engine. You should see 12 to 20 inches of vacuum, and this should also stay for a short time after shutdown. Check every connection from the pump to the tank, looking for a major loss of vacuum, or a hole in a line, etc. Don't forget the flex line from the pump to the frame. At the fuel tank connection, there should still be almost the vacuum reading you got at the pump, and it should remain after shutdown for a while. If everything checks out at the tank fitting, remove the tank and have it cleaned at a radiator shop, or replace it. I believe you've got a restriction inside the fuel tank, but check the whole system to be sure.
Jerry

Just came in from working on truck again. Open spigot on gas tank to see if any debree coming from gas tank. Looks clean. Before reattaching tank when assembling had put coating in tank and then pressure washed the inside.

Could you be a little more specific on attaching Vaccum hose and where. I think I understand but want to make sure before trying it. Thanks, Scott

An ignition coil will exhibit those symptoms when it goes bad, works fine cold and shorts out with heat. I have seen more people mess up a perfectly good fuel system when the real culprit was electical. As always, when troubleshooting only change one thing at a time so you know to put it back the way it was before trying something else in the event that the problem gets worse.

Baldy

Thought that too and replaced ignition coil when I put a new radiator and electric push fan.

Now you see my delmia. Its getting that I have replaced everything but the whole engine.

I just now hooked everything up and she runs fine again but not took her out for a run. Suggestion from car parts store to put a electric fuel pump on so when she starts to sputter to switch it on when needed. So now working on that.

Scott,

I had the same prob. as you, ether worked but nothing else. What shape is your carburetor in? My first guess would be that the carb. needs a good cleaning (only because that's what mine needed). I disconnected the fuel line going to the carb. and directed it to a bucket. Turn the eng. over and see if you get spurts. I know you can't measure the pressure like this but the fact that you just replaced the fuel pump 'should' overshadow that question. I don't know about vacuum or those types of things,

IMO, electric fuel pump is only addressing the SYMPTOM. I'd say you have an intermittent problem with your carb. Get a kit ($13 from NAPA) and completely clean your carb. up. Don't forget to document your needle settings before you take them out.

Rance (Not a mechanic. Not even on TV)

The electric pump will only turn the fuel starvation problem into a flooding problem, plus the mechanical pump might not draw fuel through the turned-off electric pump very well.

Most general-purpose vacuum gauges come with an assortment of fittings to adapt the gauge to various applications. I just use a short piece of rubber hose, attached to the inlet fitting of the fuel pump, or the fuel line at the tank outlet fitting, and plug the gauge hose onto that with the tapered adapter that comes with the gauge. A good-working pump at normal idle speed should supply a pint of fuel in 30 seconds to a catch can attached to the fuel inlet line of the carburetor. If there's fuel in the carb float bowl, it should idle for 30 seconds with the fuel line disconnected while you make the test. Just be VERY careful not to spill gas onto hot parts like the exhaust manifold. If the volume test is low, proceed with the pressure and vacuum checks.
Jerry

Thanks for all the help. Its 100 degrees here today took it out for a run. Yes it acted up again but the electric fuel pump did the trick. Installed between the gas tank and the fuel pump with a with a switch that I turn on only when I need it. Its a flow through pump that you can use with your diaframe pump.

Found out that others use this application to assist the fuel pump with acurate pressure for street running.