Diagnosing an Engine Cutting Out

[alfreema]

My condolences. Well the fuel inlet coming straight out the front instead of a90 degree elbow is a give away. The card isn't a 75 or 76 .the#s are behind the throttle linkage on the drivers side.clean it up and post the#s here.then we can tell you what carb you have.not saying the carb won't run great...

Interesting.  Well I will assume it's not original and I will go look for those numbers again.  I have looked a few times based on this thread but just couldn't for the life of me see anything (I think I was in too much of a hurry each time).  I'll give it a real thorough check this time.

[454Man]

http://www.recarbco.com/technical/rochester/qjet.html

[rickyharp]

Total newb here, but wanting to learn!

BEGIN LONG STORY -- FEEL FREE TO JUMP TO END LONG STORY TO GET TO THE POINT

1976, Chevy Camper Special with a 454.  This baby was purchased by my great uncle who died, passed it to my grandfather who died and passed it to my mom.  She doesn't want to die just yet so she quickly gave it to me. 

Anyhow ... it sat on my grandpa's farm for a looooong time while he was alive and unable to live by himself and it just weathered away.  I decided to go check it out one day and when I flipped open the lid a rodent so large I can only describe it as Ratzilla was standing on the radiator staring me down eye-to-eye.  He was determined that I wouldn't eat him, and I was determined not to poop myself.

After the standoff I was able to inspect and that Godforsaken rat had chewed through every dang hose and copper wire in the joint.

So I decided I wanted to restore this rusty, weathered, rat food back to it's former glory.  I had it towed to an electrical shop to get all the critical wiring redone and then to a mechanic to get it running fairly nicely.  Then I spent way too much on a near cab-off restoration (we did everything EXCEPT take the cab off -- I should have went ahead and done that).  Then I took it down and had a whole new interior put in.

END LONG STORY, BEGIN THE POINT

All was well for a while.  Then several weeks ago my wife was driving (I know, I know, don't say it), and it started "surging" on her badly while she was on a highway.  I had it towed to a Chevy dealer and they were unable to get it to repeat.  So after a while I just went down and rode with a tech and it cut out once early in the ride and that was it.  We just chalked the one slight cut out to "warming up".

Well I dropped off the tech and proceeded to drive home and sure enough at about the 7 mile mark it starts cutting out on me.  My wife described it as a surging but now I know why.  It would cut out, and then suddenly get power again creating a surging sensation.  But really it's just cutting out.

Instead of hauling the thing back to the Chevy dealer, who somehow wasn't able to reproduce what I was able to reproduce after the very first time driving it since we dropped it off, I'd like to troubleshoot this thing myself if at all possible.  That might be a big IF.

Soooooo ... what is the absolute first thing in diagnosing this problem?  I'd like to take a very methodical approach and start with the most obvious things to check and proceed from there.

Where do I begin?  (And please understand I don't know squat about any of this, but I am willing to ask a lot of questions and keep trying).

Thanks!

I had a 1966 chevy truck that did the same thing to me,What I found was that the truck sat for a long time with gas in the tank,the gas went stale and had curroded the inside of the tank.When I started driving it once and a while,pumping gas into the tank,it started to mix up the corrotion in the tank that would get pulled over the pick up screen and cause it to run all the gas out of the line from the tank to the motor then it would die,like it was out of gas[about 4 miles each time]We would shake the truck and it would start back and go another 4 miles and die again.So I replaced the tank,lines,fuel filter,and rebult the carb and it ran fine ever since.Maybe that is your problam.

[thefarmboy21]

I have had 3 similar cases to this scenario. All acted like exact same problem on 350 chevy's so I'll get straight to the point and tell you the three quick things to check.

1. Choke flap lose and was sucking shut randomly. This is the easiest thing to test. Simply wire the choke flap open, OR if you're brave like we did, wedge a piece of 3/8 or so fuel line or air compressor hose in the choke flap to keep it open an drive it

2. Fuel tank not getting proper ventilation. Just take your fuel cap off and drive it.

3. Bad ignition control module OR coil. I you're unfamiliar just have someone else check/swap one or both out. More likely to be ign module.

4. Something else that I've had experience with, tho usually they don't act this way, but I'd put a new fuel pump on it.

Regardless you're losing fuel or spark. Check fuel stuff first then ignition stuff and I'd search for lose ground and/or hot wires shorting out.