[61 389-348]

I have a very strange problem with my base 389 63 Grand Prix. Under full throttle for more than a few seconds, it runs out of gas and starts surging.

I had the tank out for the second time today, it was clean like last time, but still dumped it and filled with fresh gas. I replaced the pickup sock again, and blew through the lines frontwards and backwards, and that was every section of line, section by section and everything was clear. I’ve replaced every section of fuel line except for the main stainless steel lines. I’ve had 6 fuel pumps, the original AFB rebuilt and that didn’t help so I have an Edelbrock 1406. The situation seems to improve for a while after replacing something and then ends up back at the same problem. It’s not ignition, but I did plugs wires, cap, and a new Petronix igniter 2.

I’ve had the car for a very long time and it has run very strong for a base 389 and trouble free until like an idiot, I put about a 40% mix of 112 octane race gas up at Norwalk during the Ames Tri Power Nationals trying to race it Friday night. All the problems started then and I mean immediately for my first run all of 10 minutes after getting the race gas. I've used a 10-15% mix of 100 octane Union 76 race gas since I"ve had the car with no ill effects. I’ve had two more fuel pumps in it since I did the 112 octane … an Airtex from Ames and a Carter pump

What on earth am I missing here? I've tried everything I can think of multiple times and still can't fix the problem. It will cruise ok, but full throttle for more than 5 or 6 seconds and it’s running out of gas.

[Engine-Ear]

Not that it's your problem but I have had an airtex pump fail on me (see one of my first posts on PY) and with the crappy customer support I encountered on my experience, I will never use one again. Hopefully your (and everyone's) results will differ.

Could your strainer/inlet sock be collapsing?

If not fuel, could your ignition system (specifically the distributor & related parts) be a culprit?

[stevep]

Try running the car out of a fuel jug with an electric pump to see if the problem is gone.

[mike nixon]

Check for rubber fuel line collapsing BEFORE The pump, Check vaccum on the pump inlet. Pressure on the outlet. Volume Should be a pint in 30 seconds.

I'm curious if there's a problem with a line or with the cam eccentric.

[66bonne]

Quite a puzzle. Have you checked the float level ?

Jim

[61 389-348]

Originally Posted by Engine-Ear

Not that it's your problem but I have had an airtex pump fail on me (see one of my first posts on PY) and with the crappy customer support I encountered on my experience, I will never use one again. Hopefully your (and everyone's) results will differ.

Could your strainer/inlet sock be collapsing?

If not fuel, could your ignition system (specifically the distributor & related parts) be a culprit?

I've had several different kinds of pumps in there. Currently, it's a Carter I got from NAPA. And the tank sock was replaced not long ago, maybe a month, and then again today with the correct delco strainer. Everything ignition related has been replaced, although it sure doesn't feel ignition related. I replaced the Petronix 1 with the Petronix 2. That fixed a old problem with 1st of the day crank times so I got something out of it.

I do know that none of this happened prior to using the Sunoco 112 octane race gas I got from the pump inside the track at Norwalk. I almost didn't make it back to the hotel. Filling the tank and diluting the race gas helped.

This all is drving me nuts and getting expensive. I just can't figure this one out.

[61 389-348]

Originally Posted by stevep

Try running the car out of a fuel jug with an electric pump to see if the problem is gone.

I'll try one more mechanical pump and then an electric pump is next.

[61 389-348]

Originally Posted by mike nixon

Check for rubber fuel line collapsing BEFORE The pump, Check vaccum on the pump inlet. Pressure on the outlet. Volume Should be a pint in 30 seconds.

I'm curious if there's a problem with a line or with the cam eccentric.

I've replaced all of the rubber line several times as this is one of my top suspects once I could find nothing else wrong. Also a slight puncture or hole would do the same to the suction and I can't find anything. The stainless lines were done at the time of the restoration and still in very nice shape. The lines appear to be free and open, blowing either way through them, front to rear or rear to front.

I hope not on the cam eccentric, but going to an electric back at the tank will bypass that. It's sustained full throttle when it does it. Sometimes it's 3 or 4 seconds and sometimes it's 10 -15 seconds before it does it. This is what's so confusing.

Btw, if I go to an electric, where do you use for power?

[61 389-348]

Originally Posted by 66bonne

Quite a puzzle. Have you checked the float level ?

Jim

I had the Carter 9635 rebuilt twice with no improvement. And we did check the float level, but yeah, that's exactly what it feels like …. Like the bowl is running dry. And then a new Edelbrock 1406 at least got me to Dream Cruise and back, but the problem has steadily gotten worse again.

This is just about the strangest thing I’ve ever run into to and worse because it’s not very consistent.

[61 389-348]

Originally Posted by stevep

Try running the car out of a fuel jug with an electric pump to see if the problem is gone.

And it is just a little stumble at throttle tip-in and at sustained full throttle, but I had once get so bad that it was the tow truck to get home.

It sure was fine getting back from dream cruise in 2011

http://youtu.be/8wH7F0oCAes

[Option 382]

Have you drained your fuel tank of this 112 fuel and put in fresh fuel of the octane that has been working for you?

[63gpman]

Great vid by the way!!

Sounds like a fuel or electronics issue but you have been down that road with everything. Doubt it is internal, but have you completed a compression and leak down test?

[61 389-348]

Originally Posted by Option 382

Have you drained your fuel tank of this 112 fuel and put in fresh fuel of the octane that has been working for you?

I got to Norwalk with about 6 gallons of pump premium and put about 4 1/2 gallons of the 112 octane in. I filled later that night which seemed to help and it's been about 6-8 tanks of pump premium since. I took this car to dream cruise a couple of weeks after Norwalk and put about 800 miles on it total just back and forth to and during dream cruise. The tank also has been removed and emptied completely twice.

[61-63]

Pull the top off the carb and check the size of the holes in the seats with a drill dex and dial micrometer. The old Carter needles and seats had .10 holes I think it was. Current manufacture Edelbrocks have .085. The Edelbrock high performance seats are .10. What is in your car may be undersize from a bad batch of needles and seats and if so you can just drill the seat out and then debur the hole both sides with a slightly larger bit turned backwards on the hole by hand.

You may have done this but if the fuel line from the carburetor to directly above the fuel pump is rubber then replace it with aluminum tubing.

The stumper here is that this started at Norwalk when you used racing fuel? You don't remember also adjusting something when you did that?

The stumble when you open it up would be either the accelerator pump or the vacuum secondary mechanism or auxiliary air valve weight.

What it is doing at WOT says you are running out of gas.

[61 389-348]

Originally Posted by 63gpman

Great vid by the way!!

Sounds like a fuel or electronics issue but you have been down that road with everything. Doubt it is internal, but have you completed a compression and leak down test?

I don't know what it could be internal. Uses zero oil, doesn't smoke and pulls very strongly at least while it gets gas to the secondaries.

[63gpman]

I agree, just looking at the total "Health" of your set up.

[65WJ]

What type of fuel filter are you using?
The afb has a brass filter at the inlet housing.

patrick

[61 389-348]

Originally Posted by 61-63

Pull the top off the carb and check the size of the holes in the seats with a drill dex and dial micrometer. The old Carter needles and seats had .10 holes I think it was. Current manufacture Edelbrocks have .085. The Edelbrock high performance seats are .10. What is in your car may be undersize from a bad batch of needles and seats and if so you can just drill the seat out and then debur the hole both sides with a slightly larger bit turned backwards on the hole by hand.

You may have done this but if the fuel line from the carburetor to directly above the fuel pump is rubber then replace it with aluminum tubing.

The stumper here is that this started at Norwalk when you used racing fuel? You don't remember also adjusting something when you did that?

The stumble when you open it up would be either the accelerator pump or the vacuum secondary mechanism or auxiliary air valve weight.



What it is doing at WOT says you are running out of gas.

Most of the line from the fuel filter to carb is stainless and has been replaced. When I replaced it the 2nd time I went from 5/16ths, which had been fine for 12 years, to 3/8ths. All sections of rubber hose has been replaced several times. I’ve checked and rechecked and rechecked all the fuel line.

After Norwalk and before Dream Cruise I had the Carter 9635 rebuilt twice with zero improvement, and went to the Edelbrock 1406 out of desperation to get me to dream cruise. It was way better for a couple of weeks. It ran fine in some street action with several GTOs, but would once in a while after a long period into the secondaries, start running out of gas. The tip-in stumble has developed recently.

When I put the 112 Octane in at Norwalk there was a very short line in staging so I think it was maybe 10-15 minutes before I got to run. I didn’t think I was going to make it until the end of the track. It was a very hot day and I was doing it primarily to control any detonation. I changed nothing else and the car ran fine all the way up. The 112 octane is the absolute beginning of all of this.

Two weeks later in Detroit I saw lots of action and you had to be into full throttle for a very long time before it would do it again. It was good enough that it handled situations like the below just fine. I mean what on earth does any red blooded American think is going to happen when this light turns green.

http://youtu.be/4GPFMNlgV7k

It's since has gotten much worse again.

[61 389-348]

Originally Posted by 65WJ

What type of fuel filter are you using?
The afb has a brass filter at the inlet housing.

patrick

I've also had 6 or 7 fuel filters on it. It's a factory A/C car so it has the 1/4" vapor return line. Newest AC Delco (from Ames) fuel filter went on it last night with no improvement. It's the standard front left of the engine filter in the stock location. There's no filter in the carb inlet. None of the filters have ever been blocked and you can blow through them fine. I have a bag of them.

[63gpman]

Just went through a bunch of your youtube vids. Nice work!!