Stalling after driving for about an hour...

[68NewportDDD]

I gotta stop getting so distracted and post this article. Every time I go to post it I start reading about other folks' problems instead!

Here goes... 1968 Chrysler Newport 2 door slicktop, 60k original miles, 383, 727 Torquflite (Original engine & trans - car was delivered with a Carter 2 BBL; 2BBL intake manifold). The car had sat for about 8 ~ 9 years in a garage before I bought it.

The following replaced in the past 6 months:
Ignition (switched from points to electronic)
distributor
rotor cap
distributor cap
plug wires
plugs
fuel filter
fuel lines (from the fuel pump to the carburetor)
condensor
Coil (edited)
air filter
Carburetor (Holley 4BBL 650 Street Avenger)
Brake booster
Master cylinder
Brake lines
New drum brakes all of the way around
All new belts
Stock single exhaust replaced by a true dual with an H pipe (Magnaflow mufflers) - all welds, no clamps

The dual exhaust was the last modification. THAT really brought the car to life; got it running like a champ finally.

I have been running unleaded, 93 octane fuel with ethanol. I have put just under 1k miles on her in the past 6 months.

The distributor, ignition, plugs, plug wires, carburetor all done by a local shop - they work on older cars regularly - owner of the shop was the one that recommended that I go with a new Holley 650 Street Avenger (now that I think about it - the carb might be a 570 CFM), electronic ignition, and new distributor. The mechanic that replaced the carburetor said that I should give it an oil change and replace the plugs after about 500 miles. I have not done either yet. The exhaust system was replaced AFTER the rest of the work.

I have been driving it, usually once per week for short trips (<10 miles round trip). I wait for the car to warm up and the fast idle to kick down before taking it out. It runs great on these trips; no issues.

When I have had her out on longer trips though - twice now - Once today and about a month ago (70's and overcast today; low 90's and sunshine about a month ago) the same thing happened: It's running great (thermostat indicates 190) then starts to cough and hesitate some, runs for about a mile more then dies. I let it sit for a minute, turn it over and it starts right back up and runs fine for a while longer then the cycle repeats (sputters, dies, sit for a minute, starts back up with a little more cranking and throttle than usual).

I am thinking that it is a fuel delivery issue - like the rubber fuel lines are heating up and collapsing possibly? The mechanic that did the work removed the steel fuel lines we installed and replaced with rubber lines (kinds pissed me off - looks like crap now).

I have heard possibly the condenser, fuel lines, Fuel level in the bowls (float adjustment). I am thinking maybe a fuel filter replacement since I have had the same fuel filter on since I did all of the work but I did not replace nor clean the gas tank.

This week I am going to order a steel line setup for the carburetor as well as a clear fuel filter and a fuel pressure gauge


The gas tank was NOT replaced when I bought the car nor was the old gas drained. We just cycled through the old gas. Have done nothing with the gas tank and the fuel lines running from the gas tank to the fuel pump.

Any suggestions where to start?

 

[rapidtrans]

Possibly the coil or elec. ign. module going bad? Pertronix perhaps?
A weak or bad coil often starts acting up when it gets hot as engine warms up.

 

[Big_John]

My first thought went to a possible bad ignition coil and then I noticed in your pictures that the coil is mounted on the A/C compressor with the terminals pointed down.

I once read about how the ignition coil isn't 100% full of oil and it may effect some coils to be mounted "upside down", particularly when the coil isn't intended to be mounted that way (like in an old VW for instance) . That came from directly from a ignition coil manufacturer, so that's a pretty good authority.

So... Since I see the mounting AND you are having some issues that might be coil related, I would say an easy thing to try is to mount the coil where it belongs on the manifold and see what happens.

 

[mopar440]

Check if your losing spark, I still run points. If your using a Mopar ign module, check that ground is super clean behind it

 

[Davea Lux]

The coil mount is wrong and that needs to be fixed as noted. Check to be sure that whoever updated the ignition also installed an electronic voltage regulator. Electronic ignitions does not play well with the old mechanical regulators because they generate lots of static which destroys electronics. Take the fuel filter off and blow it out, if it is full of rust or other crap, your problem is likely fuel delivery related. If the fuel pump was not changed after the car sat for ten years, it is also suspect. Ethanol blend fuels degrade quickly in cars that are not driven and can leave a big mess in the fuel system and the degraded fuel also eats up rubber parts like the fuel pump diaphragm and the fuel lines.. There is a filter sock on the fuel pickup in the tank and those often get clogged if the tank is full of sludge. These are some things to check.

If the problem is fuel related, you probably will not be getting a squirt of fuel from the accelerator pump in the carb. Remove the air cleaner and look down the carb throat to see if you are getting fuel when the throttle linkage is moved the next time it quits. No fuel, the carb is likely dry from fuel starvation. If the coil, the ignition module or control is bad you will not be getting spark when you remove the coil wire from the distributor and crank the engine. Place the coil wire about 1/4" from a good ground and you should see spark. If not your problem is ignition related.

Dave

 

[68NewportDDD]

Thanks for the input! Will start with tbe coil and fuel filter.

 

[CanCritter]

sounds like your gas line is to close to a heat source and is perculateing your gas once it gets hot enough.....is fairly similar to a faulty fuel filter only once the gas cools down your fine to go again....if nothing else easy check to rule it out..bin der done dat

 

[Big_John]

One other thing that I notice is the rubber fuel line is sitting right on the exhaust crossover. It may not be your issue, but it's still not where I would want it. Plenty of steel line kits for that carb out there, so it's an easy fix.

 

[68NewportDDD]

Thanks for the tip Big John! I am looking for a steel line kit with a fuel pressure gauge now

 

[CBODY67]

What about the gas cap? Is it the type it needs to be?

 

[68NewportDDD]

What about the gas cap? Is it the type it needs to be?

Gas cap is good; looks like the correct one that came with the car.

Oddly enough though; I can only get a max of about 10 gallons in the gas tank...even after running it dry. The tank was replace in 2004 by the 2nd owner and I THOUGHT that this tank should hold 20 gallons. I can only get a max of 10 gallons in it at a time ... and the gas gauge does not currently work (I would imagine in need of a new - or at least cleaned - FSU

 

[cbarge]

Since you have electric choke already, I recommend blocking the heat crossover since it is no longer needed.
It will drop the temps at the carb by over 110 degrees. You will have to pull the intake however but worth the trouble.
Did this to both the 66 300 and 68 Newport.
Also use heat sheathing on your fuel line.
One final recommendation is a 1 inch carb spacer to help isolate the carb away from heat. Not necessary but will start first click of the key hot every time and gain some bottom end-- not much but will be noticable.
Hope this helps.

 

[68NewportDDD]

Hope this helps.

Thanks CBarge!

 

[57fury440]

Where is the ECU mounted? Check the ground. I had one that had almost the same problem. It would run for a while then shut off. Mine was a Chrysler orange box. I replaced it with a Standard box from a parts store and it is still working over 10 years later.

 

[cbarge]

Thanks CBarge!

Youre welcome.
The Boab you can see the sheathing on fuel line.
Also notice no paint burnt off intake since heat crossover is blocked..

 

[1970FuryConv]

Oddly enough though; I can only get a max of about 10 gallons in the gas tank...even after running it dry. The tank was replace in 2004 by the 2nd owner and I THOUGHT that this tank should hold 20 gallons. I can only get a max of 10 gallons in it at a time ... and the gas gauge does not currently work (I would imagine in need of a new - or at least cleaned - FSU

I agree with you and Dave and would drop the gas tank. Something is wrong if it will only fill to half capacity
Gas Tank: Are vent hoses clogged or plugged?
Fuel Gauge: if ground fuel sending unit wire, does dash gauge go to full. If so gauge OK.
Fuel Sending Unit: does it have ground clamp? If so and gauge is OK, need new sending unit.
Gas Tank: have a radiator shop clean it out. Debris in the bottom of the tank can get unsettled and clog pickup on long trips. (same is true of fuel filters, especially if horizontally mounted). When the debris drop back to floor of tank, car may act like nothing wrong.

 

[68NewportDDD]

Since you have electric choke already, I recommend blocking the heat crossover since it is no longer needed.
Hope this helps.

Thank you for the advice. Help me out here: Where is the heat crossover?

 

[68NewportDDD]

I agree with you and Dave and would drop the gas tank. Something is wrong if it will only fill to half capacity
Gas Tank: Are vent hoses clogged or plugged?
Fuel Gauge: if ground fuel sending unit wire, does dash gauge go to full. If so gauge OK.
Fuel Sending Unit: does it have ground clamp? If so and gauge is OK, need new sending unit.
Gas Tank: have a radiator shop clean it out. Debris in the bottom of the tank can get unsettled and clog pickup on long trips. (same is true of fuel filters, especially if horizontally mounted). When the debris drop back to floor of tank, car may act like nothing wrong.

Thank you fo the advice. But I could use some help:
1) Where to find the vent hoses?
2) "if ground fuel sending unit wire..." How do I do that?
3) Going to drain the tank this Winter and drop it, take it to a local shop to be cleaned (or order a new one)

 

[1970FuryConv]

Heat X-over: Center ports between intake ports. Blocked mine.

 

[1970FuryConv]

Thank you fo the advice. But I could use some help:
1) Where to find the vent hoses?
2) "if ground fuel sending unit wire..." How do I do that?
3) Going to drain the tank this Winter and drop it, take it to a local shop to be cleaned (or order a new one)

1) Vent hoses: top front of gas tank.
2) You can run a ground wire from any known good ground. If needed, use a long wire with alligator clips on the ends and attach 1 end at negative battery cable. Pull wire off fuel tank sending unit and attach other alligator clip at wire. Watch gauge in pass compartment. If it goes to full, immediately disconnect. If not, bad wiring or bad dash gauge.
3) Good move of cleaning or ditching the tank.