[61 389-348]

Originally Posted by kwt63cat

61 389-348,
Since you've replaced fuel pumps, filters, carbs, and rebuilt carbs, I'm leaning towards something with the lines. Not the rubber lines since you said that you replaced all of them, but the steel lines. Maybe a kink that you missed but likely a piece of rubber from the old ones stuck at a bend or at the fitting end. Also there is a piece of line from the pump to the inline filter. Did you check that line and the one from the filter to the carb. It's hard to diagnose this sort of thing without having hands on it. It's time to go to a fuel pressure gauge and positively confirm a fuel problem like EE has suggested. Good luck. Ken

I replaced all the rubber sections of the line multiple times and visually looked for any bends, breaks, splits, kinks in the steel lines. What I haven't done is try to run anything through it, but compressed air and of course fuel. I'm going to get on this today or in the morning.

[66bonne]

Following this thread with great interest as it is a real puzzle. But I wonder if this thread has a contagious virus as my fuel pump went out last night !!

Jim

[61 389-348]

Originally Posted by 66bonne

Following this thread with great interest as it is a real puzzle. But I wonder if this thread has a contagious virus as my fuel pump went out last night !!

Jim

I had it happen two years in a row up at Norwalk.

[61 389-348]

Originally Posted by 6T5 Cat

I had a similar problem one time. It turned out to be the power line to the electric choke was losing contact with the connector on the choke and therefore the choke was not operating properly. Without tension to hold the choke open it would close under hard acceleration and it was just like running out of fuel. I checked everything in the fuel and ignition systems and it drove me nuts for a couple of hours untill I found the problem. I read where you blew air through the fuel lines, but that doesn't neccessarily mean there is not blockage somewhere restricting the amount of fuel passing through the line. It may possibly be allowing enough fuel for part throttle operation, but not enough feul for full throttle operation. I had that problem once also. Blew compressed air through the line and nothing came out except air; I took a roll of .032 safety wire and started feeding it through the line and encountered a partial blockage. I've seen a bad coil fail at higher rpm, but ran normally during normal driving conditions.

Ok, choke has power and seems to be operating fine. I replaced the hot line just be sure I didn’t have an intermittent break in the line someplace.

Tomorrow, I run some safety wire through the main fuel line. Then fuel pressure gauge. Then time for a .357

[6T5 Cat]

If you take the tank down again check the sending unit tube for obstructions, too.

[65WJ]

I toss out a couple other thoughts.
How is the advance in the distributor? What about extra air getting in the carb at wot? That would make it nose over or die as I call it. Let off the gas and it would catch back up. Might have a bit of tunnel vision and need to think outside for a minute.

patrick

[61 389-348]

Originally Posted by 6T5 Cat

If you take the tank down again check the sending unit tube for obstructions, too.

Did that the last time we had the tank out. Clear.

[61 389-348]

Originally Posted by 65WJ

I toss out a couple other thoughts.
How is the advance in the distributor? What about extra air getting in the carb at wot? That would make it nose over or die as I call it. Let off the gas and it would catch back up. Might have a bit of tunnel vision and need to think outside for a minute.

patrick

Replaced everything including going from the old petronix to the 2. I have a huge filter on the car so it shouldn't be air.

The major factor is that it was ok up to the moment of the 112 octane and very bad about 5 minutes after.

[66bonne]

This thread is keeping me up at night !! You've inspected, cleaned, repaired and/or replaced everything in the fuel delivery system. Except for the fuel pump cam eccentric but that wouldn't be related to the 112 fuel.

How is the gas tank vented ?
Racking my brain to think of anything.

Jim

[61 389-348]

Originally Posted by 66bonne

This thread is keeping me up at night !! You've inspected, cleaned, repaired and/or replaced everything in the fuel delivery system. Except for the fuel pump cam eccentric but that wouldn't be related to the 112 fuel.

How is the gas tank vented ?
Racking my brain to think of anything.

Jim

Had a few gas caps too and it is a vented cap. The only piece I haven't replaced is the main stainless steel line, but I can't see any pinches or cuts. It was replaced when I did the restoration. I'm going to run through the line tomorrow to see if there are any blockages that compressed air isn't showing me

[Engine-Ear]

I maintain that there's valuable information in a fuel gauge reading when the problem occurs...

[61 389-348]

Originally Posted by Engine-Ear

I maintain that there's valuable information in a fuel gauge reading when the problem occurs...

I agree. First I'm going to 'snake' the main fuel line to see if there's any blockages and if it's still doing it, which with my luck, it certainly will be, then upward and onward to other things. I think I'll video it and put it up on here in the next couple of hours.

[65WJ]

Originally Posted by 61 389-348

Replaced everything including going from the old petronix to the 2. I have a huge filter on the car so it shouldn't be air.

The major factor is that it was ok up to the moment of the 112 octane and very bad about 5 minutes after.

that is why I threw out a couple options. Tunnel vision. Something else could have gone wrong at the precise moment you introduced the fuel from Norwalk, causing the belief the fuel itself caused the problem.
Anything is possible.

How is the coil, wiring to the petronix? Did you try weaker springs on the advance? The internals of the distributor can wear out.
like matt mentioned put a fuel pressure guage to confirm or deny it is a fuel pressure problem.


patrick

[Deadhead]

Good one on coil. That is possible. Bucking and what have you can occur with that. Easy to test.

1st rule of troubleshooting - always start with the easy stuff first.

[61 389-348]

Originally Posted by 65WJ

that is why I threw out a couple options. Tunnel vision. Something else could have gone wrong at the precise moment you introduced the fuel from Norwalk, causing the belief the fuel itself caused the problem.
Anything is possible.

How is the coil, wiring to the petronix? Did you try weaker springs on the advance? The internals of the distributor can wear out.
like matt mentioned put a fuel pressure guage to confirm or deny it is a fuel pressure problem.


patrick

I've also had three coils. It's not so much related to rpm as it is load.

I set the timing by ear (always have) and get it to the point of detonation and then back off just a bit. Tunnel vision is what concerns me and why I'm posting here. I feel that it is something simple and the tunnell vision is preventing me from finding it. I'm going out to the garage now to 'snake' the main fuel line. I had to coffee up with some 112 octane 'race' coffee before I started on the car

:-)

Fuel pressure guage is next.

[61 389-348]

fuel lines are clear front to back. Still doing it though and badly so I recorded it

http://youtu.be/hGdTrldobqk

[Engine-Ear]

Another idea: what is the voltage TO THE COIL PRIMARY during "the event"?

Rig up a voltmeter between the coil primary and ground with the display in the passenger compartment... most Fluke DMMs have adequate lead lengths.

[61 389-348]

Originally Posted by Engine-Ear

Another idea: what is the voltage TO THE COIL PRIMARY during "the event"?

Rig up a voltmeter between the coil primary and ground with the display in the passenger compartment... most Fluke DMMs have adequate lead lengths.

OK, another one that I hadn't though of although the coil has been replaced for the 3rd time now.

I recorded it and put it on youtube. It's sounded like this through three coils

http://youtu.be/hGdTrldobqk

It really does sound like its just running out of fuel.

[61 389-348]

Ok, I just woke up from a nap and didn't read it correctly that you said TO the coil primary. And true, I need to find longer leads

[mkoser]

I think you eliminated fuel issues.. I think it's electrical. Maybe due to increased vibration from higher RPM. After starting the car, I'd run an alligator clip from Battery + to the coil +. See if it still does it. That would rule out coil primary issues.

Check your wire going to the distributor. Put a new set of points in it.

MK