91 corolla starts, stalls, won't restart

[bsavitsky]

I park my 91 corolla dx wagon with 1.6 engine facing downhill. When i start it in morning and let it idle to warm up, it sometimes stalls and won't restart. i have replaced the fuel pump, the relay under the hood and the relay in dash that switches power to fuel pump from startup mode to normal operating mode. Towed it three times, always starts after tow. Last time, only towed it 30 yards to level spot on top of hill and it started and ran fine [don't know if hill is coincidence]. Running out of money and ideas. Any suggestions?

[bsavitsky]

I'm a longtime Toyota owner, but new to this site. i need this car for my daily commute to work. I'd appreciate any input, as my mechanic and myself are stumped...thanks...Bill

[kcwa]

Now I am just thinking...but I gotta ask: how much gas do you have in the gas tank? Could it be that being parked on the hill, not knowing how steep the hill is, but may with a shallow tank of gas the level is beyond that of the fuel pump. Thought of this especially since you mention it being fine on the level.

I will not go into the discussion of the old days when had to back up hill for this very reason...I am gonna date myself.

[new echo owner]

Agree with kcwa about the fuel level in the tank.

N.E.O.

[tashirosgt]

Can any forum members tell us if some sensor might be shutting off the cold start injector on the second try at starting?

The on-the-hill theory could be checked by jacking the car up so it is level the next time it won't start.

The mechanic could jack it up so it wasn't level in the shop and see if that reproduced the problem.

[new echo owner]

Look at the fuel gauge when it won't start to see if it is fuel level related, then put a few more gallons in the tank, if it starts, you have found the cause.

N.E.O.

[kcwa]

bsavitsky...please keep us posted on what you have figured out the problem to be.

[Tire Shredder]

First, go to the toyota dealer and order yourself a repair manual it will pay for itself many times over. I don't mean owner's manual...repair manual.

as for your problem, I would be a large some of money your coolant temperature sensor has failed. I got my corolla for free because it had many problems...it needed a lot of TLC.

One of those problems was exactly as your described issue. Once the car gets warm the car will get an incorrect signal from the coolant temperature sensor. Confused, the car will start the cold start injector in an attempt to increase idle, as if the car was cold. The problem is that the car is actually now warm and this just results in a very rich condition. It's so rich that the car will actually stall out and die. The engine, effectively flooded. You won't be able to restart the car until the fuel has somewhat evaporated and the spark plugs dried again.

if you're ever in the car and notice this happening, you'll certainly see the check engine light come on. I tracked this problem down by checking the engine's error codes which pointed me to the coolant temperature sensor.

bottom line is check for error codes first, but I can almost gurantee it's your coolant temperature sensor. Not the one for the cold start injector (called the cold start injector time switch) or the one for your temperature gauge, but the one that the ECU reads. This sensor is low on the engine, near the transmission (under the distributor). It has a green plug. You will have to remove the air intake and most likely the bimetal vacuum switching valve (blue thing with two hoses coming out of it, right beside it) so you can get the sensor out.

you will lose a bit of coolant so make sure a drain pan is under the car. top the rad up with distilled water (you will lose probably less than half a litre). let the car get warm with the rad cap off (so coolant is overflowing) to help burp the air out of the system. put the cap on and drive like normal. after driving and the engine is COLD again (several hours later) check your coolant level.

done deal.

I got my coolant temp sensor for the junkyard for $4. easy fix for a serious problem.

also, if you need to restart the car when it's flooded (so you can get the part etc.) you can do so by flooring the gas pedal while cranking. this will disable the EFI system and allow the combustion chambers to be cleared of excess fuel. pay attention to the engine rpm while driving and at stop lights. Aswell as the check engine light. The car will stall again eventually once you od have it started. the CE light can give you a warning it is about ot do so. you can avoid the stalling if you have a manual transmission by keeping the engine rpms above 3000rpm when you are at rest.

hope this helps!

Steve

[kcwa]

Originally Posted by bsavitsky

When i start it in morning and let it idle to warm up, it sometimes stalls and won't restart.

I get the point about the coolant temp sensor but what throws me off is the comment "it sometimes stalls"...makes it sound inconsistent. Can the coolant temp sensor be inconsistent? I don't know...

[Tire Shredder]

Originally Posted by kcwa

I get the point about the coolant temp sensor but what throws me off is the comment "it sometimes stalls"...makes it sound inconsistent. Can the coolant temp sensor be inconsistent? I don't know...

yup mine behaved exactly the same way. the error code describes the coolant temperature sensor failure as a short or break. This short could occur over a specific temperature range which the engine is never always at the exact same temperature (it will vary a few degrees with the thermostat and radiator fans doing their job). compounded with this the ECU is never constantly monitoring the temperature. It takes instantaneous voltage samples at regular time intervals. At the particular times it takes a reading, the sensor may be operating as normal, and no problem. but it may take a few samples in a row where the sensor is giving an incorrect output....Cold start fires, engine floods, car stalls.

obviously it could always be something else. but from the limited information provided, that's where i'd start!

[kcwa]

Originally Posted by Tire Shredder

if you're ever in the car and notice this happening, you'll certainly see the check engine light come on. I tracked this problem down by checking the engine's error codes which pointed me to the coolant temperature sensor.

I wonder why bsavitsky's mechanic did not pick up on the engine error codes? Also have not heard back from bsavitsky in four days ....

[kcwa]

Ya know...have not heard back from bsavitsky in nearly a week. I am getting the feeling that the problem with bsavitsky's car was that it was not having enough gas in the tank when park on a hill. If it was a sensor figured then would of heard back with a "hey, found the problem"... but not hearing back could be due to the embarrassment of the low gas issue. Hmmm....

[new echo owner]

Anything is possible, but there is no reason to be embarrass though, sometimes the most obvious things are the ones that we missed most of the time.

N.E.O.

[kcwa]

NEO...you are right. I know I have been there many times before myself. This is why I subscribe to the thinking of "Occam's Razor" where the simplest answer is usually the correct answer.

[new echo owner]

We are only human!

N.E.O.