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By unknown | Dec 02, 2009 | COMMENTS [ 0 ]

I HAVE a few questions that I would like you to help me with.

I HAVE a few questions that I would like you to help me with.

I bought a 1985 Toyota Corolla Avante Twincam 16V in August this year.

To my knowledge the car hadn't been used for a long time when I bought it.

I soon found that it was lacking power and would not rev when I put my foot down on the accelerator pedal. Eventually it wouldn't even start.

Suspecting faulty valve timing, I then removed the cambelt with the help of a knowledgeable friend and tried to realign the camshafts. This didn't solve the problem.

(I am not sure whether we did it correctly, using the marks on the cams - perhaps you could one day give some hints on how to align the camshafts properly.)

Further investigation led us to believe that the fuel pressure at the injectors was insufficient, so the petrol pump was replaced with a new one.

Thereafter the car did start, but there was blackish smoke from the exhaust and the idling speed was too high.

The distributor was adjusted to bring down the idling revs - again I am not sure whether that was the right procedure. The black smoke was then gone, only the white mist of condensed water vapour was coming out.

I drove the car like that, but it was jerking and prone to stalling.

We decided to pour some injector and valve cleaner into the petrol tank. After a while the car became difficult to start again and I found that the spark plugs were wet with fuel.

We again aligned the camshafts, and also cleaned the spark plugs and cranked the engine with the plugs removed, to get rid of excess fuel in the combustion chambers.

Then the car fired up, and I have been driving it till now, the third week, but I still experience the jerking, as if the engine isn't getting enough petrol.

Another thing I realised when changing the petrol filter is that the petrol coming into the filter was rusty.

What could cause that? Is my petrol tank dirty, and, if so, how should I go about cleaning it? My radiator, too, is rusty - what should I do?

I also want to change the air filter to a more durable one - would it be alright to fit a K&N filter, which I prefer? And how do I adjust the engine's idling speed?Robert

Robert, as a first step I suggest that you try to clean out the petrol tank, because blocked filters or dirt in the injectors could be the root cause of some of the symptoms you mention.

Sediment in the petrol tank is a common occurrence in older cars, especially if the car has been standing for a while.

Condensation of the water vapour in the air inside the tank can also, over time, give rise to a small amount of water in the tank and, since water is heavier than petrol, this will collect at the bottom of the tank where it can cause rust.

Some petrol tanks have a drain cock at the lowest point which allows you to drain the contents of the tank, but others don't have this useful facility and then it becomes a mission to clean out the tank properly.

You might find it easier to buy a handful of in-line filters, and just replace them frequently until you have got rid of all the dirt swirling around inside the tank.

You should also then look at the mesh screen over the petrol pump's pickup, which might have become clogged in the process.

If the jerking persists after you have done this, I suggest you remove the injectors and take them to fuel injection specialists for checking.

Petrol injectors are built with tolerances as small as one micron (that's one-thousandth of a millimetre!) and even a tiny amount of dirt or leakage inside an injector will affect the engine's performance.

For the job of removing the injectors, as well as for checking the alignment of the camshafts, I would prefer to have a workshop manual for the engine available (try - look at the Haynes manual for the Toyota Corolla A to E, September 1983 to September 1987, but make sure it covers your engine), or I would obtain beforehand as much advice as possible from the Internet or experienced Toyota mechanics.

The same goes for adjusting the idling speed - you may find that by altering the distributor setting you have masked one problem, but created another.

I am always sceptical of aftermarket parts that are not factory approved; a K&N air filter, good as it may be, will probably have different airflow characteristics compared to the factory one, and this may upset the delicate balance achieved by thousands of hours of testing by the manufacturer.

The dirty radiator we shall leave on the back burner for another day.

Good luck with the Avante - it's a milestone model in the Corolla's history and will certainly give you lots of joy once it's fully sorted.


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