Continued mystification of one T4WD....

[emmahumpfritter]

Hello,

Well, I've returned to trying to get one 86 Tercel 4wd SR5 to run somewhere close to normal. My conclusion has been for quite some time that these are indeed the best vehicle ever sold in the US, minus the insane carbs/vacuum mess going on under the hood. The latest issue is: I can get it to run almost "good" (idle at 1100 rpm's, run and drive "good") until I say, stop somewhere, then come back and drive again, then for no reason I can fathom, idle drops to 600 rpm's, hesitates at all speeds and generally runs like crap. This CAN work itself out in a few miles or days by nothing I've done. I did manage to set the timing 10 degrees advanced and button up a vacuum leak (and I currently can't find anymore with carb spray). I'm stumped but not down. My over-arching thoughts right now are the Tercel's 80's computer "fights" the owner at every turn to tune and tweek and maybe the truth is a weber will solve most of these issues.

Any ideas appreciated.

Brenton

[ARCHINSTL]

While ancedotal - I fought Goldie's infamous 1900-2300 RPM cycling back and forth with the (I think) OE carb and two subsequent reman (not by me) carbs. This continued both before and after a reman distributor and EGR modulator and scoured EGR valve and multiple testings of every component and miles of vac hoses. The only thing I could come up with was a malfunctioning 'puter, about which the FSM is totally and completely mum in every respect.
After installation of the Weber (and disconnection of all emissions stuff), this cycling stopped.
Tom M.

[Petros]

emmana,

My car has almost the same behavior. It runs fine and I just live with it, but sometimes I set the idle where I want it, and the next day it is back up at about 1100, but occasionally settles down below 1000. Since it starts and runs good, and I have no flat spots or other drivablity issues I live it since that is easier than trying to track down a issue that is not a problem.

The only time I had it stumbling for a day or so is when I sucked water down the carb (crossing a very swollen creek), it went away in a few days. So there appearantly places where water can get trapped in the carb and mess things up. Try a fuel dryer perhaps (an additive that removes trapped moisture from the fuel system).

Have you cleaned out your carb? The stumbling could be loose dirt that foats around in the float bowl and randomly gets caught in a jet somewhere, and than floats free again. It is not too difficult to pull the top off the carb (while still in the car), and VERY CAREFULLY (watch out for the tiny parts), clean out the bowl and spray carb cleander in the jets. If you are careful you can usuually get the top off without damage to the gasket (use a light amount of gasket sealer to put it back together).

Good luck.

[emmahumpfritter]

I fiddled with it again today, now it runs worse. I'm done with the stock carb....just plain done.

Question/Plea: I'm self employed and adventurous (meaning I have time and a will to travel) would any of the core Tercel gurus here on the site be willing to have a fairly compentent junior member (heck, I can seem to keep an 87 Toyota 4wd van running good for 10+years!) pull into their driveway some weekend with all his own tools, a weber straight out of the box and every other part needed (collected in advance) to do a weber install--only needing guidence and sound advice. I'll even bring the beer (any flavor requested) shoot, I'll even through in my extra altimeter for their trouble.

I have a near perfect rust free specimen here that for the life of me CAN NOT GET TO RUN CONSISTENTLY RIGHT. It's like these cars are cruel pranksters or something.

I'm commited...I've just had it with these stock carbs.

Brenton

[Petros]

Where are you at? You are welcome anytime at my place, we even have guest quarters. (I will have to get clearance from the wife first).

I have not done a weber conversion on a Tercel, so someone else might be better for that. But I am very familiar with both the weber and the Tercel and all its systems, and not intimidated at all with doing a carb swap. We have a few local guys here that might come over for kibitzing, how about coordinating that with our August Pacific Northwest meet?

[emmahumpfritter]

Yes! and I know right where you live (approx. 30 miles North of Seattle on I-5 right?) I worked there for a while. I have old friends to visit in Washington State. I'm pulling together the swap list now.

Brenton

[dlb]

hey brenton. when i bought my terc last summer it ran ok but had would lose power around corners sometimes, and a few other minor details. my pal convinced me to let him put a weber in it and by god, it is probably the single best thing you can do for these vehicles. obviously, it won't fix any other problems you might have (poor compression due to worn rings or whatever, worn distributor, faulty plugs, etc.) but if the other systems are in order it will drive a hell of a lot better and shouldn't increase your fuel consumption--except for the first week when you keep flooring it because it's just so exciting to drive a terc like a sports car. after putting the weber in, the cornering problem (due to the floats in my old carb) went away and the engine accelerated much more smoothly. the engine is much more responsive now and performs best between 3000-5000 revs. it's pretty sick, i wish you luck with the swap!

[Jarf]

Brenton
I was having significant issues also.
The worst being I would have it running nice and put the air cleaner on and the idle would change. Couldn't find any vacuum leaks by traditional methods either.
One day I checked the mid-body screws accessible through the venturi and got nearly a full turn on them and the car ran a lot worse.
Ended up overhauling it and replacing all the rubber bits and needle and seat and life is much better but I still have a 200 rpm variance in that sometimes it idles at 800, sometimes 1000. I found that the throttle shaft is worn and actually moves a bit hence the change in idle.
Now that everything is clean I realize that I even have a slight intermittent fuel leak (1-2 drips) out the shaft after shut down, usually on hot days.
Might be worth checking to see if you are have the same issues going on.

-Burntboot.

[emmahumpfritter]

Thanks guys, Mine also does the running badly around corners and up hills (not down though?!) I just got word (PM) from Slatterdog (the other Mn. tercel member) that he's willing to oversee a weber swap. This obviously will be much closer than visiting Washington state, though I hope to do that sometime this summer after my wagon is running well.

I have a highly worn out "parts" tercel 4wd at my dad's place in Nor-Cal that has nearly everything wrong with it EXCEPT the carb works wonderfully. I concidered pouching the carb from it but decided to stick with my gut feeling that the stock carbs on these buggers are more/less the only real problem these cars have, and from all the reading I've done, a well installed weber solves the problem.

Thanks Spatter, I'll be in touch and won't be a pest. Thanks everyone else for the ideas and offers. I somehow can rebuild a Metro from the ground up in a weekend but the 80's carb/smog system going on with these tercels has me feeling like a bumbling idiot.

Brenton

[neddflanderz]

computer? I didn't know tercs had a computer. I thought they were too old. What is it? a Vic-20? Commodore 64?

[splatterdog]

All "feedback" carbs have a computer. What surprises me is the total lack of on board diagnostics. According to schematics there is a check connector. No CEL on the dash to flash codes or any info anywhere on pulling codes. Does it even store malfunction codes ? I wonder if even the dealer can plug in?

A problem I will never know....

[emmahumpfritter]

I've almost completed the parts list for the Weber swap/install. Still hunting down the vacuum line caps (ideas?) My local advanced doesn't have the size needed. Checking with AZ in STC this weekend. Looking like I'll be taking this intimidating job on myself (I think I can...I think I can...)

[ARCHINSTL]

RE vac line caps...the only ones I used were on the TVSV to simply keep dirt out of the thing, and one on one of the two gas filter outlets (the other goes to the dist). Also used one on the restricted port of the dist vac advance (originally from the HAC valve). So - the only one that actually eliminates a vac is the one on the gas filter.
I removed all of the EGR stuff, the EBCV, the HAC, and the metal spaghetti. The vapor canister is still there, but vented to the atmosphere.
Tom M.

[Petros]

make a vac line cap with a short piece of vac line with the correct size sheet metal screw in one end. Use some gasket sealer on the screw so it stays in place. Works fine.

[takza]

The dependable type are the vinyl ones...the rubber type can split? You find the vinyl used in hydraulics a lot?