Bucking / Bogging / Stuttering at speed

[keith]

Smell your oil for gas. When these fuel pumps go bad, they usually leak into the engine and contaminate the oil.

[irowiki]

Okay so I didn't touch a thing on the car after the battery died and I got it towed home. Figured I'd fix the cranking issue first, which I did. In the meantime, the float bowl was soaking with a bit of carb cleaner.

Got the starter fixed, sprayed a little more carb cleaner down the throat and into the float bowl too, and she started right up, and ran just fine! :shocked:

Reminds me of the carb I just put in the 1st gen back in Feb, I had to do the same thing. I'm not convinced it is fixed, I'll keep y'all posted.


Edit: still acting up. Seems the cold circuit in the carb could be gummed up.

[irowiki]

Swapped carbs. In the process of swapping carbs discovered the "top" choke breaker diaphragm wasn't connected to anything, and (dun dun dun) the fuel line from the pump to the carb had a crack in it! I'm sure both of those weren't helping.

Either way I got the "new" carb on and she starts easier and seems to be running better. Only issue is I can't get the idle below 900, even by screwing out the idle screw. I think either the TP is acting up, or maybe the AC idle up.

[dlb]

paul, i had a similar isse of high idle on the latest rescue terc. the carb ran excellently at all temps and RPM but was idling just a bit too high. i found that the throttle shaft was a bit of a vacuum leak so i chalked the high idle up to it. i managed to work around it by adjusting the idle mixture screw to be slightly richer and that brought the idle down so it runs great in all respects now. might be worth taking a look at, after confirming all the obvious stuff of course (all hoses routed properly, all diaphragms good, etc.).

[marlinh]

What is the idle you have it at now Paul?

[irowiki]

It is at 900, which isn't so bad, the old carb idled really nice at about 650-700 though. I was more concerned that dialing the idle screw out changed nothing, and there may be something stuck. Going to check the TP and A/C kick up later.

Fast idle also doesn't work, but I rarely have a car where it does work as designed

[marlinh]

900 isn't bad, and yes you should be able to get more adjustment out of it so maybe there is something else going on.

[Petros]

check the trottle cable is not adjusted too tight (so it allows it to return to idle), and check the adjustment oppoisite the throttle cable for the device that does not allow the throttle to slam shut. Also, you might spray some light lube on the linkage and in the throttle cable.

[keith]

There is an issue with the throttle plates in this carburetor. The screws that hold the butterflies to the shaft can come loose allowing the butterflies (plates) to shift slightly so they don't completely close. It is hard to detect visually.

Do not attempt to back out these screws, they are flared so they are not meant to be removed. Just open the throttle completely and see if the plates can move at all, if so, fiddle around with them until they allow the throttle to completely close and then tighten the screws.

[irowiki]

paul, i had a similar isse of high idle on the latest rescue terc. the carb ran excellently at all temps and RPM but was idling just a bit too high. i found that the throttle shaft was a bit of a vacuum leak so i chalked the high idle up to it. i managed to work around it by adjusting the idle mixture screw to be slightly richer and that brought the idle down so it runs great in all respects now. might be worth taking a look at, after confirming all the obvious stuff of course (all hoses routed properly, all diaphragms good, etc.).

After I fixed the timing (found out I hand timed it to 0 degrees) with it set to 10 degrees and the vacuum advance hooked up, she now idles at 1300-1700 randomly. I mean, idle will be steady, but what she's idling at will be in between those numbers. Usually closer to 1400 once warmed up.

Idle screw does nothing so I'm going to poke around and see.

I also replaced the dizzy rotor, cap, plugs and plug wires. Put a used but working vacuum advance on as the old one was bad. Got the timing set to 10 degrees. Seems to run mostly like a dream now. Got 30 MPG on a recent round trip over the mountains

Amazing what a difference 5 degrees makes, at 0 degrees timing she seemed to ran fine, but lacked power and fuel economy went into the hole.

[dlb]

30 mpg is a good start!

the changing/high idle speed still sounds vacuum leak-ish to me. if you check that out and all is fine, remember to check the idle mixture as well as the idle and fast idle settings. the throttle positioner can also cause high idle if it's improperly set.

[xirdneh]

what about the adjustment screw on the front of the carb
did you try backing it off
sometimes it will give more range to the idle screw

[irowiki]

The throttle positioner? I'm going to mess with that tonight.

[irowiki]

Yup, it was the TP.

Someone had replaced the vacuum line going to the TP with one too large, so it wasn't sealing right, so not only was it a vacuum leak, it was preventing the TP from working at all!

Purring along at 650-700 RPM idle.

Surges a tiny bit when cold, but who knows on that one...maybe the choke breaker.

[irowiki]

30.1 mpg this time, with city driving and commuting to work mixed in!