1990 Corolla LE dying at/accelerating from stops

[kevinf89]

I have a 1990 Toyota Corolla LE with roughly 240,000 miles on it that I bought almost 2 months ago. The previous owner mentioned a stalling issue, which until now, has been intermittent. Now it is getting worse and I need to get it fixed.

It seems to happen most at operating temperature. The temperature gauge does not work. It is completely dead. Shorting the sensor to ground seems to make a fan come on, but it was the fan on the passenger side (car has A/C), and does nothing for the gauge. I do not believe the vehicle is overheating. Infrared temperature gun gives me roughly 350-400f at exhaust heat shield, 170-190f at top of radiator, 160-180f at upper rad hose and 100-110 at lower rad hose, 170-190f at thermostat housing.

When it stalls, the engine will usually be hesitating before hand. As in, when you give the engine throttle the acceleration is delayed. The engine may also lose a few hundred rpm during this delay. Otherwise the vehicle drives okay at any speed. Coming from a stop, the engine will hesitate and if you do not give it enough throttle it will die. When the engine is doing this the CEL comes on for a few seconds to a minute or so and then goes back off. If the engine dies, it will not restart for at LEAST a minute or so, usually longer. It seems to be cranking fine, just won't start. Occasionally it might start but will chug, stumble and then die again. Although when it starts it can go either way. Most of the time it still hesitates and dies at stops. Other times it will run fine. Just yesterday the car started to hesitate but the CEL came on and the behaviour ceased. Engine behaviour is irrelevant of gear. Engine will hesitate and die in neutral and park just as well as the drive gears.

I'm thinking something is overheating, but not the engine. Research has led me to believe either the fuel pump or alternator. Last guy's mechanic said fuel pump. I had a mechanic play with it for an hour or so and he said it's probably a fuel issue. Nobody pulled any codes, not sure how to get them. I think it may possibly be the alternator because the car will run and accelerate fine (well, it moves the car and won't die/chug/make strange noises) and the headlights will be noticeably dimmer at idle than at higher engine speeds.

Anyone have any ideas? Supposedly the fuel pressure can't be measured without splicing a T into the line.

Mechanic pulled up back seat and says it looks like that access panel goes to fuel pump, but I remember reading somewhere that this era of corolla had the sending unit in that location and that the fuel pump was under the trunk. Has anyone worked on this year/model to say definitively?

[90 GP]

You need to get that temp gauge working so you don't end up with an overheat condition and a blown head gasket which can easily happen in this engine. Either a bad sender or a blown fuse is likely the cause. Since it's setting a code here is how to retrieve by reading flashes of check engine light. Check for vac hose leaks which could be contributing to your hesitating.

http://www.troublecodes.net/Toyota/

[swalay]

What kind of shape are the spark plug wires in? My engine was having similar hesitation upon acceleration and I went through the vacuum hoses and replaced a few and also replaced the plugs and a new wireset and it made a tremendous difference. when was the last time the car had a tune up of sorts

You should try replacing the temperature switch to see if you can get your temperature readings back. Could it be disconnected possibly? This is what the switch looks like it is $16 at autozone do you think maybe its disconnected or loose? mine was loose so I had to pry the contacts of the connector with a small screwdriver to tighten it and keep it from falling off the switch

The fan switch looks like this one and is on the thermostat housing

on my 89 with 4af carb engine the fan switch won't work right unless the temperature switch is connected. and with the fan switch disconnected the radiator fan should work in a fail safe mode and run all the time. does yours do that with the fan switch disconnected?

[kevinf89]

Doh! The temperature sender was disconnected completely. (How the hell does this happen? Bad mechanic?) I plugged it back in and the gauge was working fine now. What I thought was the temperature sender before actually turned out to be the fan switch. That circuit seems to work, too. I disconnected the fan switch and the fan kicked on. I also checked under the seat for the fuel pump: no such luck. Fuel pump lead continues deeper into the rear of the vehicle.

Car is still stalling and hesitating intermittently. Although it seems to run better? Now, with the temperature gauge working I can see that it is coming to operating temperature quickly enough and staying there (middle of the gauge, right?). Does anyone know if the ECU uses this sender for calculating fuel input?

I checked the codes. If I'm reading them right I got: 12, 22, 43. According to the manual in the glovebox those are: RPM Signal, Engine Coolant Temperature Sensor, Starter Signal.

Of note: previous owner decided he didn't want to spend the money to repair the ignition properly so he had a button wired to crank the starter when the key is 'on'. How much of a headache will this cause me?

Another note: When the engine stops working properly, overdrive stops working properly. It will either kick me out completely or drop out/come in intermittently. The shift in/out seems fine, though. Just like its being kicked out BECAUSE of the engine problems?