I have idle problems too... but they're different! sort of.

[thegoldnugget]

So after doing a search through the archives i didn't see anything like this, and I know it's probably ten different things working in concert to make my car run like crap but...

When the car has been sitting for a while (3-4days) it starts and drives fine. but on longer trips (15-30miles) it starts hesitating in the 2000-3000rpm range then as soon as i let my foot off the gas, and the RPM's drop to 1200 or so it just stalls. IF i'm rolling i can just pop the clutch and it will start again but if i'm stopped i have to crank and crank the engine with the gas pedal held to the floor to get it to start again, then it runs REALLY rough until i rev it up a bit, (incomplete combustion smoke out the rear at this point) then just sort of rough until i let my foot off the gas and it just dies again. I've check for obvious vacuum leaks, disconnected hoses, linkage issues, etc. nothing.

P.S. the car is slowly getting worse, the first time it did this was after driving 200miles, the second time 50miles, and today it started to do it just after 10miles. ugh. any thoughts? thanks for being patient with yet another carb question.

thanks!

nathan

[Typrus]

Fuel pump maybe? Could be a growing pin-hole in the diaphragm? Pull the dipstick and smell the oil. Smell like gas? If so, replace the pump and change the oil, then again after 500 or so miles if the smell doesn't come back as bad.
I'd think that could do it, potentially, as it might have trouble sucking at low RPM, but move enough higher up?

Could be a timing issue, check the advancing mechanisms? Maybe gummy?
Pull a spark plug and examine it.


IS there an oil slick on your firewall behind the fuel pump? If so, clean it off and see if it comes back. If it does, replace the fuel pump.

Hows your fuel filter? Could be plugged with sedament. Let it sit for a day or two and the heavier bits fall off the filter element and allow better flow when restarted, until they get sucked back up on the paper and re-plug it. You could try that. Filter should only be around $8.

[keith]

Let me add a couple of things, check the fuel level in the bowl of the carb thru the little window to see if the needle and seat are working properly, when your having the problems. If everything else fails, you might check the torque on your intake manifold bolts, though this usually causes just the opposite problem.

There could also be some crud in the carburetor bowl that works its way into the mouth of jets but settles out when just sitting.

[thegoldnugget]

Thanks for the suggestions, they definitely gave me a good place to start. here's what's happened today:

first off the car barely started, and then ran real rough at a higher idle ~1200rpm, then quickly died.

i did the following...

Replaced fuel filter
checked for leakage around fuel pump, didn't find any, no gas smell in the oil.
replaced distributor cap, rotor
replaced spark plug and wires

the fuel level in the bowl through the glass window is where it's supposed to be.

and the problem is still there... next up... carb rebuild? all those little bits of smog equipment?

[ARCHINSTL]

Welcome to the Club!

A few suggestions before doing anything to the carb (keith had a good suggestion, though):
1. Check the stickie in the Repair Guides section for correct placement of the various vac lines (the stickie is for Federal vehicles - not CA models, but the diagrams for that persuasion can be found in the FSM available for download - see the first page). Also the quality of the little lines; they tend to deteriorate in the bay. This is to include the tubing to the brake booster (I had a leak in mine, and it had an effect).

2. Check the TVSV valve - it is quite important (there was a thread just this week about it). There are also other threads on it.

3. Check the EGR valve and its modulator; again, there are several threads in Repair Guides on rehabbing these from, among others, takza and moi.

4. I would suggest investing in a MityVac vac pump - not too expensive ($30+/-) - and it can be used for purposes beyond testing the 152 little vac guys - like bleeding the brakes.
Tom M.

[Typrus]

Hmmmm..... Just do as I do. Kill every non-essential vacuum bit. No, but seriously....

Start by making sure the big fitting to the brake booster hose is tight. It likes to wiggle loose. If it is loose, remove it fully, clean it up, put on some Teflon plumbers tape and put it back, CAREFUL NOT TO STRIP THE MANIFOLD. Do thi also for the other vacuum goodie to the manifold with 2 fittings on it.

Heres a HUGE one to check. Take the air cleaner housing off. Make sure that the big hose that connects to the white bit on the cover (you'll find out when you pull the cleaner) is hole-free, not badly chafed or burned, and fully connected. Uncracked as well. That is one of the largest sources of vacuum on the setup.


With the air cleaner off, plug the big hose, plug a short length of hose to the other vacuum sources of the manifold (remember where everything goes!) and then plug the sources of vacuum on the side of the carb (again, remember where they go... The 3 sources on the pass. side of the carb are quite important) The whole point being to prevent any vacuum hose from seeing vacuum in that huge mass of tubing. If when you fire it up, the problem is solved (performance will still be crappy with things like the dist advance unplugged) then you are suffering from a vaccuum leak.... somewhere. As daunting as that is.


Check the tension on your carb hold-down bolts. Should be 12mm? 4 of them as well. Manifolds.



Hmmmmmmmmm........... Heres a thought- look under your car. Find the cat. Is it bolted or welded on? If welded, ignore this- if bolted, soak the bolts in PBBlaster penetrant for 2 days, hitting them at least 4 times a day, then remove the cat. See if your problem is solved. If so, plugged cat or muffler. Albeit, that would not cause it to not run right away, it could have contributed to a bigger issue. Or a result thereof.


Look up the Weber Carb conversion.

Or just go buy a Redline-Weber Kit K740.

[gatemaster]

after years of frustration I installed a weber and all of my carb problems went away. now the car runs like a swiss watch. the stock carb is a piece of junk, I came to that conclusion after owning 2 tercels.

[Petros]

You should check the fuel cut-off solenoids. These devices cut off the fuel supply when you down shift (it reduces emissions and improve economy slightly). I think these are connected by vacume line to the right fender, and are in two locations on the carb, one on the back and one on the left side. There is a simple test in the manual to check these. The behavior you describ could be caused by this fuel cut-off solinoid if it is being stuck closed.

Although the carb is a bit small, if it is running correctly it is very driveable. I finally have had mine running good for more than a month (cross my fingers-knock on wood-etc.). Other than being a bit baulky when cold (normal with all carbs), it runs good and I just logged 33mpg average for my last tank of gas (my best ever for mixed driving).

Replacing it is costly and unnecessary if you know how to diagnois the carb and emmision control system. Though as it gets older tracking down the various hose leaks, etc. can be come a regular chore. Rebuilding it can be done inexpensively, but use great care-if the tiny internal parts are not installed properly it will never run correcly.

Good luck.