Damon

If the M/C solenoid in the carb "clicks" when you turn the key on, it's good, RIGHT?? Not so fast. Ran into a weird one last weekend. Thing would run rich despite all the usual attempts at a cure. The engine was all stock and the ECM said all was good, except it ran too fat (occasionally throwing a code). I rebuilt the CC-QJet, checking everything I usually do and being thorough about it, certain that this would fix whatever problem it had although the carb had all the original seals which is a pretty good sign it's never been messed with or opened up. Ran better, but the same basic problem remained. Swapped on a known-good CC-Qjet I have laying around it ran great. DEFINITELY a carb-related problem of some kind. Tested the TPS- good. Tested dwell on the carb and it was good, although it was way up the top of it's range trying to lean things out (when in closed loop).

Long story short, I tore into it many times looking for something.... ANYTHING that could cause the problem. I called my brother for assistance (he's better with the electronics than I am). Went down the trees until we hit a likely candidate.... a bad M/C solenoid. But how could that be? It clicks!!!

Maybe, but the solenoid MUST TEST GREATER THAN 10 OHMS RESISTANCE ACROSS THE POLES (with the wiring harness plug disconnected from it, obviously). This one measured 4 Ohms. Definitely outta spec. M/C solenoid got replaced and it's fixed this time- dead bang, no questions asked.

I tested a few other known-good M/C solenoids I have laying around. They all tested at 20-22 Ohms. So one that's outta spec shouldn't be too difficult to spot. Incidently, another common problem if the solenoid is outta spec is ECM failure from the excessive current draw though the bad M/C solenoid (unknown in this case since the owner just got the car and didn't know any history).

Obviously, this is WAY WAY down the list of things that typically cause problems with the CC-Qjet, but it's so easy to check it should become part of your routine if you regularly rebuild these carbs, diagnose problems related to them or even if you just like to do a thorough tune-up on your CC-QJet equipped car from time to time. Very easy to add this simple test to the list. I know I added it to my permanent list of things to check last weekend!

CowboyBilly

Wow, good info! I've got one doing the same thing so guess what I'll be doing this afternoon. BTW, do you have a source outlining how to set the M/C?

Damon

You mean how to adjust it? Not really, unless you have access to a running engine so you can see the M/C duty cycle as you drive.

However, to get you reasonably close here's how I set it.....

Turn the LEAN STOP all the way down until it LIGHTLY bottoms and then back it out 4 turns.

Next, remove the IAB valve.

Insert a very small screwdriver down the IAB passage until it touches the top of the rod hanger inside the float bowl. Check the travel of the hanger from bottomed out to fully up. You'll feel very slight spring pressure pushing it up. Should be exactly 1/8" of total travel in it. You can measure this by marking lines on the shaft of the screwdriver in both the up and down positions, using a fine pen and the top of the airhorn to move the pen point across as your reference point. Then just measure the distance between the 2 lines on the screwdriver using a machinist's rule or whatever's handy.

If it's more or less than 1/8" adjust the RICH STOP until it is exactly 1/8". Don't be afraid to do this procedure several times until you're absolutely sure it's right.

Reinstall the IAB valve, turn it down until it LIGHTLY bottoms and then back up 4 turns.

Idle mixture screws should be in the range of 4-7 turns out from lightly seated, but their exact setting is more application specific.

You're done. Good baseline setting to work from. Done LOTS of CC-QJets this way, many that I never even had the opportunity to tune on a live engine and they always worked just fine.

CowboyBilly

Sounds like I'm on my way, thanks for the info

Bill

five7kid

iTrader: (14)

I would assume there's an upper bound for the resistance requirement as well. But, when you reach that, it'll probably quit clicking.

Any idea of the resistance range?

Damon

Well, like I said, I tested a few known good ones and they all came in around 20 Ohms. So if 10 is the bottom end I would think 30-40 Ohms would be the ceiling.

PneumaticTire

tested mine for kicks, measured in at 25 ohms.

JFROG

is that measured in ohmsX1k (1000) or do i need to use a digital ohmeter, i used an analog meter and got 0.