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Old Yota Problem #2

I was just wondering if anybody can help me out with a couple questions regarding my old 1977 Toyota Hi Lux. It’s not a big problem but it is starting to get colder now and up until now when I start it it turns over on a dime. Since the temperatures have gotten to around -10 C in the morning it has a little more trouble. So I will do my best to explain what happens but I am not to car savy so I may not have all the terminology correct. When I turn the key and the vehicle will crank but not start. Once it does start though it starts really well. After that it will sound really “chuggy”, be billowing out white smoke from the tail pipe and the time between chugs will get longer and longer until it eventually shuts off. If I keep my foot on the gas it will stay going and if I warm it up enough with my foot on the gas it will stay going but I can just start it in the morning to warm it up and walk away or else it will be off when I come back.

Any ideas? I tried to attach a video of the start up but it was too large and tried to attach a video of the sounds it was making but I dont think it is going to work.
Thanks In Advance!

Sounds like a choke problem with the carburetor. I haven’t messed with one of these in what seems like a million years but I seem to remember the choke being engine coolant operated.
The white smoke could be coolant seeping past a choke shaft and into the carburetor bore.

The running ragged, stumbling, and dying could be caused by a faulty choke pull-off diaphragm.
The choke pull-off is a vacuum pod on top of the carb and is located next to the choke housing.

The purpose of the pull-off is to instantly pop the choke flap open a small amount to prevent overchoking. If faulty it leads to a stumbling engine due to too much enrichment. They can be checked with a vacuum tester or by sucking on a piece of vacuum line attached to the vacuum ort on the pod and noting whether the flap moves a bit when cold and that it holds vacuum. Hope that helps.

Your car may have ignition points which have to be changed or adjusted. At least see if you have them and check ignition wires and coil wire for swollen areas near the ends. Make sure coil wire is all the way in the holes.

In you know someone who knows carbs, get them to help you take a look at this. The choke setup is pretty basic, and if it’s the choke or high-idle step cam, they’ll be able to spot and fix it post-haste.

These carbs also have a unique eccentricity. They operate their accelerator pumps via a lever on the side of the carb pulled by the accelerator cable and returned via a spring. If they get gummed up, the lever that activates the accelerator pump sticks in the activated position and becomes effectively inoperable. I’ve fixed a couple of these in years past that were exhibiting exactly your symptoms by washing the lever fulcrum down with carb cleaner or WD40 (I’ve used both successfully).

ok4450- I am not familiar with this truck but does it really have coolant at the choke shaft?" What I recall about cars of the late 70s, they all ran like this in cold weather.

Luke.d6- are you putting the gas pedal to the flood and letting it back up before you crank it? That is how you are supposed to start these. When you do that the choke plate should close, a squirt of gas should spray into the carb below the choke plate and the fast idle cam should rotate onto the highest step.

My 70s Ford truck sometimes develop a similar symptom, and the problem was a vacuum hose had become loose or split and the mixture became lean. The symptom was worse when the air temp was cold. When it happened, the difference was night and day. The day before and every da before that it would start and run fine, then one morning, bam, this symptom appears. Likewise once the vacuum system is air tight the problem goes away immediately. Not sure if this would apply to your older Toyota, but worth a shot anyway.

The white smoke is simply the exhaust, which has a lot of water vapor in it, hitting the cold air and condensing. Toyota carbs typically have two choke pull offs, one that partially opens the choke right after start up to keep it from running too rich and a second one that pulls the choke open when the coolant warms up.

A lot of mechanics are not aware of the first choke pull off so it often gets overlooked. Its hard to find so you or your mechanic will need a factory service manual for your truck to get this one right.

@ok4450 do you mean hooking up a hose and literally using my lung power to suck on a vacuum hose to see if the choke opens a little? I am trying to do this as cheaply as possible. Are there any simple fixes for the pull off? Or if it is faulty it needs to be replaced? Would some simple carb cleaner loosen in up?

@Keith i think i agree about the exhaust. and the pull off. do you happen to have any simple solutions for the choke pull off?

Yes, lung power to test the pull-off. You have to plug the end of the hose with your tongue to maintain a vacuum; much like a finger on the end of a soda straw.

The choke needs to be cold and completely closed. It should open (very roughly) an 1/8" and stay open as long as vaccum is held; which means as long as the tongue is kept tight to the hose.

There is no repair on a vacuum pod like this. The rubber ages and cracks just like belts, tires, and so on.
The trick might be finding one if needed. These things are kind of antiquish and with demand being very skimpy parts houses may not carry the pod alone.

You don’t have to actually suck hard enough to move the choke pull off, you will tell immediately if the diaphragm is intact or leaking. If it is leaking, it will be like sucking air through a straw.

You need a factory service manual or a subscription to all data to identify both pull offs. I’m not sure they are both shown in a Chiltons or Helms. You might try AutoZone.com to see if it is listed in their repair sections. Replacement is the only repair.

As an alternative, you could get a rebuilt carburetor, but that is pretty expensive. If you don’t live in an area where smog testing is required, then a Weber conversion could be the best answer. The Weber carburetors are cheaper than the factory carbs and much simpler, but they won’t pass a smog check.

@keith, I put a Weber conversion carb on an '82 Honda. By tuning the carb just right, it passed emissions for years until it grandfathered out. It didn’t take much, since the carb is so simple.

If you don’t want to use your lung power, you can purchase a hand held vacuum pump with gauge for less than $20 at any auto parts store. Many vacuum operated devices in cars require a fairly big vacuum to operate, often more than most folk’s lung power can achieve. This is a tool any DIY’er who works on their own car should own. You can measure vacuum, apply vacuum, or even, in a pinch, transfer fluids out of and into hard to reach places with it.

I am guessing yours is like my 1979 Toyota truck, with 20R engine. It had coolant going to the choke adjusting mechanism on the back of the carb. The choke’s basic adjustment is to turn the choke plate more or less closed: there’s a “dial” and gradations marked on the housing back there. With the air cleaner removed you can see these gradations and the choke plate, which should be close to closed when the engine and air temp are cold. Note or mark the present position.

I suggest you adjust the dial so the choke plate is more open than at present.

Also ascertain that when you floor the gas pedal (or simulate that at the carb) you get a squirt of fuel into the carb. This will be more obvious if you hold open the choke plate while flooring it.

So I took off my air filter today and started the engine cold. Not as cold as it has been but still cold. The choke closed completely and seemed to work fine. Slowly opening as it warmed up. Early on it was still about to stall before I gave it a little bit of gas to keep it going and after a few it seemed to do better. I noticed that thing on my carburetor is leaking. When the gas is pressed it pushes that rubber gasket closed but when the gas pedal is depressed it doesn’t lift it completely off. I am still not sure on its function or if that could be the cause of it stalling out when idling after a cold start but it doesn’t look like it’s in good condition. Any explanations? If that is not the problem for the idling stalling then could the choke just be not opening enough like a few of you have said?

That lever is for the accelerator pump, underneath that accordian seal. It appears to be leaking. I believe you can only get them as part of a rebuild kit. With seals beginning to leak, a rebuild is probably needed.

I agree with busted that the accelerator pump appears to be leaking.
However, try washing the fulcrum area of the lever down with carb cleaner or WD40 to free it up. These get gummed up and prevent the accelerator pump from functioning properly… and yours looks pretty gummed up.

If you remove that seal and pull out the shaft, you will find a leather seal attached to the bottom end of the shaft. That seal may need to be plumped up by soaking it in some motor oil and massaging it. That way it will seal better against the walls of the bore it rides in.

The seal may have been leaking some gas for a long while, and that black deposit may also be in the bore. If so, clean it with a toothbrush, q-tips, rag, etc. and some solvent.

It’s still not clear to me why pressing the gas pedal when it threatens to quit is helping. It could be that it needs more gas, but it could be that it needs more air. You provide both when you press the pedal. In any case, since there is evidence of malfunction around that rubber bellows, addressing the accelerator pump is what I suggest, before any more adjusting of choke, etc., etc.