Engine problems

[TeeGee]

Hi,
I've got a 1981 Tercel that just rolled over 300000km. It's got its 2nd engine, which is at about 100000.
Some time ago it started misfiring or not firing occasionally. With time it got worse and worse and it's not at the point where I cannot drive it at all because it just doesn't develop any power any more.
When in idle, it seems almost fine. Listening to the exhaust, there seems to be a discontinuity about once a second but as soon as I push the accelerator it gets worse (still in idle). When the engine is under load (when driving), the only way to get anywhere is keep the engine at very low revs. Pushing the accelerator for more than a tiny bit results in total loss of power.
When it all started, I noticed that this gets worse when the engine heats up - at the moment I can't really say because it's pretty bad to start with.
So far I haven't done much fixing on the car. I've changed the spark plugs but that's about it. I'm happy to take things apart but I don't have experience with fixing cars so I can't look at parts and say "Yeah, that looks bad".
One more thing: I think I have a leak in the petrol tank. A long time ago, I noticed after I filled up that half the tank was gone after two days without me actually driving around. I never filled up since and I'm left with 1/4 tank at the moment. I'm thinking, maybe I got some condensation/water in the tank which stuffed it up. Pulled the petrol filter out but couldn't see anything unusual only that it seems only half filled (to the point where the cap starts, no idea if that's normal).
Any thoughts/hints what I could try do myself to fix this?

Cheers,
Tom

[takza]

I'd put a locking gas cap on it to start....gas generally doesn't just disappear? Also...people can add stuff to your tank that you don't want in there.

The filters can clog up to the point that a car won't run...and this might not be visible...so I'd put a new one in.

Then maybe add some fresh gas and some carb cleaner to that...and see if things get any better.

[keith]

As I recall, this is a clamshell type tank, so it can develop a leak around the seal of the two halves, but it is more likely to develop a leak at the base of the filler tube.

The engine problem sounds like it could be one of two things. More likely the weights in the bottom of the distributor that are used to mechanically advance the timing are frozen in place. A little WD 40 would fix this. The other thing that might cause this is a clogged main jet in the carburetor.

[danzo]

The "lack of power on acceleration" you mention could also be the accelerator pump. Fortunately this is relatively easy to check/replace and I would expect a good local parts store would be able to get it for about 10 bucks. Just remove it from the carb and check if the diaphram is ripped. It's included in a carb rebuild kit which can be had for $25 almost anywhere. Unfortunately the Factory Shop Manual (FSM on this site) doesn't say much about it. But of course the first step is to identify the problem. To me it sounds like some kind of carb problem, and a rebuild would most likely cure it.

As for the fuel tank - if you leaked half a tank of gas, you would have a puddle damn near the size of the Pacific and be able to smell it from 300km. Maybe your gauge crapped out, or some Hooligans stole your gas like takza suggested. Where I live, the Hooligans steal things a bit more valuable - but the world is a weird, wonderful place I suppose. Good luck.

[xirdneh]

I'd start with a compression check
can buy a compresson tester for under 40.00

[TeeGee]

Thanks for all your replies - now I've got something to do next weekend

I will start by looking at the distributor. I'll check the timing first to see if it's worth taking the distributor out. I've got the Service Manual; I hope with its help I can to pull it out and apart and put it back in safely after cleaning and putting some WD40 on.
Next thing is the compression test if I can find someone who has a tester.

As for the tank, the cap is good, I suspect a leak in the tank itself or the lines. As the car is parked on grass, the puddle might not have been very obvious and with temperatures in the 30s (degrees) fuel would have evaporated rather quickly those days. And I think I did notice a petrol smell inside the car for a short time.

[xirdneh]

check out the heater control cable where it runs by the fuel lines coming out of the fuel pump in front of firewall
depending on how that cable is routed
it can rub on fuel lines eventually wearing thru them

[TeeGee]

Turns out the timing was way off at around 20 in idle, so I had a closer look at the distributor and found that the vacuum advancer didn't have a hose connected to it. I also found an unconnected hose that wasn't long enough but it had a bit of plastic stuck inside that looks like a connector used to connect two of those hoses.
I read in the service manual that the timing with a disconnected vacuum advance is supposed to be at 5 so I tried adjusting the position of the distributor but even when I rotated it all the way to one end I couldn't get all the way to 5 - just close.

I suppose randomly disconnecting vacuum hoses without plugging them isn't the best thing - can I expect damage in other parts from driving around like that?

The service manual I've got is the 85 one. Some of the diagrams and pictures don't seem right for my 81 car. Is there an earlier version of it?

[4wdchico]

Get the timing right, for sure. But if it still has the same issue get a vacuum gauge and check out this link:

http://www.secondchancegarage.com/public/186.cfm

The vac gauge is the most overlooked diagnostic tool and one of the most useful. Cheap is nice also...

[takza]

Sounds like you will need to pull the dist to get the timing right. Then you'd need to find the right vac diagram for your car(on this site) and carefully go thru all the hoses and replace any that are bad and make sure they are routed right.

[TeeGee]

I've been reading for most of the day now just to get a bit more insight and to pick up some ideas. Unfortunately, I haven't found the right vacuum diagram yet. Most of them seem to have 3 hoses connected to the vacuum advance - mine only has one. At least from what I can see without taking the dist out. Good thing is, it's not stuck. If I push down on the bit that connects the vacuum advance with the rest of the distributor, it rotates. And I can also rotate the rotor shaft a few degrees counterclockwise.

For the vacuum system, is there anything I can do without a vacuum gauge? (That's assuming I find the right diagram)
I haven't actually looked at the emission control part of the FSM but it seems to be the way to go for hunting vacuum leaks. I'll go any buy myself some vacuum hoses tomorrow. I suppose they can get the right size if I bring the one that came off already.

One last thing.. where on earth is that window in the carby to check the float level? I tried finding it but couldn't; do I have to take the air filter off?

[4wdchico]

I've been reading for most of the day now just to get a bit more insight and to pick up some ideas. Unfortunately, I haven't found the right vacuum diagram yet. Most of them seem to have 3 hoses connected to the vacuum advance - mine only has one. At least from what I can see without taking the dist out. Good thing is, it's not stuck. If I push down on the bit that connects the vacuum advance with the rest of the distributor, it rotates. And I can also rotate the rotor shaft a few degrees counterclockwise.

For the vacuum system, is there anything I can do without a vacuum gauge? (That's assuming I find the right diagram)
I haven't actually looked at the emission control part of the FSM but it seems to be the way to go for hunting vacuum leaks. I'll go any buy myself some vacuum hoses tomorrow. I suppose they can get the right size if I bring the one that came off already.

One last thing.. where on earth is that window in the carby to check the float level? I tried finding it but couldn't; do I have to take the air filter off?

The correct vac hoses are not available at an auto parts store. The 'yota hoses are a bit different than the standard aftermarket hoses. Mid '90's Camry 4 cyl. cars in the JY are your best bet as they have some nice long hoses running from the TB up to the dizzy.

Your car is much different than ours in respect to the vac system. Getting your hands on the correct vac diagram is the only way to go. Most stock Aisin carbs have a sight glass to check the fuel level. On the t4wd it can be seen w/o pulling the AF, but on your car, maybe not.

[ARCHINSTL]

As 4wdchico mentioned, your (Gen I) car is different from our Gen II cars. Since you mention "km" and "carby," I presume you are in OZ? Apart from being a dissimilar car, your vac system is probably different from USA and Canadian requirements/systems which are posted on this site and in the available FSM. The N-S drivetrain is similar to our 2WD Wagons, but that's about it.
I'd think you'd need an Australian (or New Zealand ?) FSM for Gen I. Isn't there an Antipodean Tercel Club?
Tom M.

[TeeGee]

You're right, I'm in OZ, and I haven't had much luck finding a local club / forum that could be of any use. Service manuals for 1981 Tercs are hard to google. On the other hand, I did find a vac diagram where it's supposed to be - on a sticker on the inside of the hood. I've got it attached for future references or interested people.
It does seem to have show open ends but at least it tells me where to connect my vacuum advance to. Shall go and find a junk yard today after I brainstormed what a TB and a dizzy is

[TeeGee]

Alright,
turns out the thermostatic vacuum transmitting valve (TVTV) is broken. The hose I found unconnected came of the top of it and the connector is broken off, so it can't just plug back.
And it seems someone has connected the hoses incorrectly last time I got the car fixed. The hose that comes off the side of the TVTV is connected as shown in red in the attached diagram and NOT to the vacuum advance.
I don't know what that TVTV does and if that was done on purpose to make it go better but I was hoping that someone here could answer those two questions:
1) What happens if I don't get a new TVTV and just replace it with a piece of hose to get the vacuum advance connected back to the system
2) Does it make any sense to connect the TVTV as shown in red in the attached diagram?

Any idea where I could buy such a TVTV? My local wrecker doesn't have one and the car part shop doesn't have it either. I'm thinking it might be easier to get it posted in from anywhere than asking Toyota to get one for me and charge a million bucks for it.