Ever since I rear-ended someone not very hard a few months ago the engine would at first start to hesitate and then cut-out after a while of freeway driving. At first I thought it was a fuel thing because it would usually start right back up again after I stopped the car. Yesterday, I tried to get it going at least 20 times and each time it would run less until I could only get a few feet before it died. i thought about some heat related ignition problem. I believe the distributor has some kind of electronic ignition as it has a three color harness coming out of the distributor going to the coil and ground. Usually, it will start back up quickly right after it dies and run fine for a few seconds until it completely cuts out like the ignition get turned off although sometimes I felt like I could keep it alive a tiny bit longer by pumping the gas pedal. After I left it to sit overnight it started back up fine this morning, so I thought it must have something to do with the ignition. This time it didn't last longer than a minute (much longer than last night) before the engine stopped again, so everything couldn't have been that hot yet.

I pulled off the fuel feed from the carb. and gas comes out in pulses (I think, as it should. I haven't had a mechanical fuel pump in a long time). To add to the confusion, I've poured gas down the carb. After the gas boils for a while ( I was a little surprised it boiled today after a relatively short period of running), I'd crank it again and it ran a little longer than before I poured it in. I know this information isn't very helpful or clear, but does anyone have some good ideas? Checking for spark while I'm cranking probably won't help me much because I know that it usually fires up. If the problem is with the spark and not fuel, then I need to figure out if the spark goes away shortly after the engine ran... Could the accident have damaged some module in the distributor?

 

Sounds like you have done some diagnostics. I would grab a test light and start checking for voltage at the distributor and go from there. Check for voltage before failure and then go for a ride to make it fail. At first I was thinking module but it restarts!

Pat

 

I would also suggest a fuel pressure gauge at the carb inlet. On other cars I've seen with similar symptoms, the cause was crap in the fuel tank that got sucked up against the filter sock in the tank, shutting off fuel flow. As soon as the engine stalled, the crap fell back down into the tank and the car would start again, only to stall out as the crud was sucked back up. It's possible that the impact loosened this crud in the tank.

 

Thanks for the good pointers Pat and Joe. I was thinking fuel pickup too, because it seemed to be worse when going uphill or near empty tank. Does a Vista Cruiser have a fuel pickup that I can easily take out to inspect?

Pat, the problem with measuring voltage at the distributor and coil is that if I find 12V after it cuts out, I won't know for sure if it didn't cut out because there was no voltage for a moment when it cut out?.... Also, can't the module (if I have one) fail intermittently due to heat? I also heard that not having good contact at the mounting surface can cause over heating...

Joe, looking at the fuel supply again. When I saw gas pumping out when I disconnected the main fuel line, I figured that means I should have gas in the float bowl. How long does an engine run on just the float bowl. I would think it would be longer than just a few seconds?...

 

Typically when the GM ignition modules would fail, you would startup and go about 2 blocks or so and it would just die and the module would be dead to the world. Thats what makes me think of a loose connection somewhere on the ignition circuit?????

If you had a O.E. style coil and I would agree on the heat sink theory! Usually you would have to let the coil cool for about 25 mins. or so for it re-fire.

Pat

 

I did some work today and I'm pretty sure the problem is in the fuel delivery. Voltage at the coil is always between 6.4V (ignition only) to 11V when it's running. It never changed even as the engine was cutting out.

After running it for an hour this morning, I found the this: If I just let the engine idle it seems like it will run indefinitely, even at idle between 1000 or a little more. At higher idle or as soon as I want to drive under some load it quickly starts to stumble and run out of gas and then stops. I can keep it running a little longer if I pump the linkage and inject gas from the accelerator pump, probably until there is no more gas left there either. The odd thing is, when I take the 2 jet Rochester carb. apart after that, there is still gas left in the bottom of the float bowl. I would guess about 1/2". What is the float level supposed to be on these carbs and why would it stop running with some gas left in the bowl and the jets at the bottom of the bowl? How does that work? If the jets are at the bottom you wouldn't think it mattered what the fuel level in the bowl is?
Otherwise, everything looks clean. I also blew a little compressed gas into the jets while they were submerged which probably didn't do much. No sign of crud in the carb. though.

 

Did you check the fuel filter If it is just dirty enough to let fuel to idle but not keep up with a load that may be it but it goes back to what Joe said about crud in the tank.

 

Thinking the accident loosened some debris in the fuel tank and is now clogging either the fuel pickup in the tank or the inline fuel filter or both.

 

"If the jets are at the bottom you wouldn't think it mattered what the fuel level in the bowl is?"

Oooooooooooooooooooooh, contraire.

Surely you don't think the gas just pours out the jets into the engine? It would do so all the time. The gas goes thru various passages and has to be elevated above float level to be dispensed in the main nozzles, thru the magic of the Bernoulli effect in the venturi. Think sink drain trap. And so, yes, the float level matters, very much.

 

In fact, the float level affects mixture ratio. As Chris points out, the Bernoulli effect causes a low pressure in the fuel feed passages that "suck" the fuel out of the bowl through the main jets. The pressure differential across the jets affects flow through the jets. A higher float level increases the static pressure (sometimes called head pressure in fluids calculations) at the bottom of the fuel bowl just due to the mass of the gasoline. Yes, it's a small change, but it matters. One old racer trick if you need larger jets is to bump up the float level slightly instead.

 

Is your gas cap vented? Don't ask me how I know but the Vista needs a vented cap Drill works wonders

 

Is it possible that a steel fuel line got smashed flat or something moved and put a kink in a rubber hose as a result of the rear ending? Thus seriously restricting fuel flow to the carb........but not totally stopping it. I've seen it on cars before as I have a small amount of collision repair experience. I'd check all the lines/hoses real good.

 

Thanks for all the great explanations and ideas. I hadn't thought about carbs in a long time and now it makes sense. I got the car towed to my place and will look at the filters next. There was barely any damage from the accident so the lines are okay.

What should the float level on this 2 jet Rochester be?

I just did my first successful run after I removed the fuel filter at the carb. It looked quite clean. Now I have to check the gas tank pickup for dirt too. Do I have to drop the tank to get to the pickup and sending unit?

 

My bet is the coil has an internal issue.

 

5 year old thread.

 

 

Rabbit hole extraction successful!
Randy 1, car 0.
Game to be continued with cruise control...lol

Disregard this response was for Randy C with his 69 442....how it got here? Ill move it to...https://classicoldsmobile.com/forums...-start-144641/