Bad stumbling only when going uphill

[02Pilot]

OK, it's been a while. I haven't been driving my 02 much in the last few years - maybe a few hundred miles a summer. In spite of this, it has been remarkably reliable.

When I took it out a couple weeks ago, however, it started acting up. I quickly realized that every time I started to climb a hill the car began to stumble. The longer the hill, the worse it got. Level or downhill: no problems. I found and repaired a broken float pin pivot in the rear DCOE, figuring that the float hanging improperly had caused the rear carb to flood every time I went uphill. I replaced the fuel filter as a precaution, and inspected the in-tank screen, which was very clean. Took the car out once or twice in short hops - no problems.

This morning the problem reappeared. I immediately checked the float cover repair - it is intact and holding perfectly, so the problem lies elsewhere. I checked the fuel flow from the pump (Carter electric, mounted low on the forward frame rail) - it is flowing a lot of fuel, at least on level ground. I don't have a spec on the max flow I need to feed the carbs, but there's more than enough to handle the light to moderate throttle it is stumbling under. Voltage to the pump is fine. The problem appeared with a full tank; the tank is now at about half-full.

I'm going to jack up the front end and retest the pump flow. Beyond that, I'm pretty much out of ideas. FWIW, I've run this set up for 15 years without problems; nothing that would affect the fuel system has been touched recently except as noted above. If anyone's run into similar issues or has any thoughts, I'm all ears.

[Mike Self]

under load you stress the spark plugs, plug wires, coil etc...so make sure points are in good shape and have the proper gap, and all the other ignition components are up to specs.

Another suggestion--wait 'till dark, then run your engine and look for stray sparks around the coil, dizzy, plug wires and plugs. If you can see sparks, then you have a high tension ignition problem--something is leaking electricity.

cheers

mike

[BigDog]

FWIW I think the fuel pressure for DCOEs is 3.5-4psi. If you don't have a guage it's a nice thing to have under the hood for diagnosing said issues.

That being said I had fuel delivery problems which caused similar issues to the ones you are having. Turns out my fuel lines were sucking air, and under high need for fuel as well as more gravity to suck it up to the front, I was't getting the flow I needed, even though pressure was good.

I'm also running a carter in the front using the old hard line for supply then fed through braided stainless to a filter king and my webers. The fittings I used to attach the braided directly to the hard line had degraded over time and I had to find a better solution. I had problems at the joint between the hardline and the braided lines, front and back as well as at the pickup. Now that these are airtight, life is good.

Good Luck.

BD

[02Pilot]

I will certainly check both of these possibilities, though it feels much more like a fuel problem than an electrical problem to me.

I cleaned and gapped the plugs after the first incident, and I have a Pertronix installed. The wires are only a few years old, with very little mileage on them. Only the coil is old; it should probably be replaced just based on age at this point.

The idea of a fuel line connection that's allowing a bit of air into the system sounds very plausible. I use a similar setup to yours, BD - rubber line to the original steel return line along the left side, with rubber lines connecting thence to the filter, the pump, and the carbs. The lines in the engine bay are relatively new, but those from the tank haven't been touched in years.

Thanks for the suggestions. I will update when I have a chance to investigate further.

[c.d.iesel]

....and Andrej when his yellow dog was running better !

A Graduate of the 020202 Spartanburg Gathering

Good to hear from you.

Creighton

[TobyB]

Check the float levels, and the bowls for sediment in the bottom.

The stinker about the Webers is that there can be a lot of varnish

and junk in the bottom of the jet well and it'll be hard to see- but it can get

sucked into the jets, causing just what you describe.

You can pull that bottom well cover with the carbs on, but it's a PAIN!

hth,

t

[Paul7002]

timing