Continuing Fuel Problems '66 327/300

[Alex Gilmour]

I am still chasing a fuel problem. The car quit on me on the way to work this morning. It cuts out like it is running out of gas then dies completely. After it dies, it will not restart unless I let it sit a couple of minutes and crank for a minute or so. Then I can get it to fire and run normally, but if I rev it up and hold it at, say, 3500rpm, it starts acting like it is running out of fuel, again sputtering until it dies completely. The carb is a brand new Holley 3367. The car ran fine on a 20+ mile road test last night.

So, I suspect the following:

1. Fuel Pump - Can a mechanical fuel pump die intermittently? I always thought it was a working/not working thing. It exhibits symptoms like the pump isn't delivering sufficient volume to sustain the car under power, but will idle without dying.

2. Sock on the fuel sender pickup is collapsing.

3. Crap in the lines? Fuel tank looked clean and I added another filter just after exiting the tank since it has a steel line all the way to the fuel pump, and another steel line going to the carb. The rubber hose from the fuel tank to the steel line is new as well.

4. Vapor lock. Doubtful, since the lines are routed correctly and it was very cool outside, and only about 10 minutes into my drive, so the engine wasn't even warm yet.

Any other possibilities?

Thanks, Alex

'66 A/C Coupe

[Mike Ward]

Re: Continuing Fuel Problems '66 327/300

I can think of at least two ignition related problems that would cause the symptoms you describe. Just for fun, try swapping out the coil and condenser with known good replacements.

Mike

[G B.]

Check your ignition coil

It sounds like your coil is overheating and failing to me.

I've never seen a mechanical fuel pump come back to life after death.

I have seen clogged fuel filters make a car miss and even die, but usually only at freeway speeds. You can then restart the car and drive slowly just fine. There is a little metal filter in the inlet fitting of your Holley, but it has a "by-pass" mode spring that compresses when the filter gets plugged.

One time I had a fuel hose that would suck flat on the inlet side of the fuel pump. Since it wasn't leaking and it would open back up after the car died, it took me a while to find that problem.

[Steve Vaughan]

Re: Continuing Fuel Problems '66 327/300

I had the same symtoms on my '69 350 for several months. Condition was worse with car going up hill (tank lower than fuel pump). After couple of months of intermitten stalls the conditions continued to get worse. I finally solved it by checking fuel pump flow, pump flow was eratic and a new fuel pump fixed the problem. I later cut open old fuel pump and found diaphragm was cracked which appeared to me to primarily cause a loss of suction, hence the problem primarily occuring when headed up hills.

[Craig Jewett]

Re: Continuing Fuel Problems '66 327/300

Hi Alex,

I agree with the suggestion to swap the coil. The coil failure possibility is usually much greater if the weather is very damp. I had a similar problem on my S-10 Blazer. It turned out the coil resistance was very low, causing it to produce a very weak spark. The damp weather shorted out what little spark was left. By letting it sit for a few minutes, the moisture must have evaporated off of the wires, which allowed me to start it again. However, I had the same symptoms as you are experiencing, years ago on my '72 LT-1, soon after I bought it. At first I thought the engine was shot. As I gradually pushed the gas pedal to the floor the engine would speed up momentarily and then begin to die. It turns out that I had gotten a bad tank of gas with plenty of water in it. By adding lots of anyhydrous ethyl alcohol, and topping up the tank with good gas I was able to eventually solve the problem. I think the gas quality is better now, so I'd lean towards the coil being the culprit. Hope this helps..

[Alex Gilmour]

Re: Check your ignition coil

Jerry, My buddy suggested just what you did (bad coil), but it really feels like it is running out of fuel. Then, it takes a sustained amount of cranking and it feels like it is filling the float bowl, causing it to run normally until the higher revs depletes the float bowl. Then, it sputters and dies and the cycle starts again.

I am going to start with the fuel sysytem and will probably change the coil as a preventative maintenance issue since they are pretty cheap.

Thanks for the suggestion, Alex

[Tom Buddie]

Ditto on the water idea

I just went through the exact same symptoms with my '70 LS5. Turned out it was water in the tank... almost impossible to detect visually... a couple of quarts. The drain at the tank filler was plugged. Just another possibility.

[Gary Schisler]

Re: Continuing Fuel Problems '66 327/300

Eliminate your problems one by one. 1. Take a flashlight and look down into your gas tank. You can see the fuel pickup through the fill neck (the fuel strainer sock is also visible). BTW, turn the flashlight on BEFORE you get to the fuel tank to eliminate any chance of a spark. 2. Replace your fuel filter. They are too cheap to second guess. 3. I had a mildly similar problem in right hand turns, going uphill, in my 66. A new fuel pump solved the problem. Around $40 for an aftermarket unit. 4. If I had to make a wild guess, I would go with the coil. The purpose of the coil is to boost the 12 volt system to 30,000+ volts. The coil can break down internally and cause an intermitant spark. Know anyone with a good coil you can swap out to check and see if yours is bad?