Expert: Sean Halliday - 4/3/2007

Question
The car I am asking about is a 1991 Chevy Corsica with a 3.1 motor. Problem one- This car has first off had the a fluctuation of a possible over heating problem when idling. It would rise up near 210 degrees or so then once started driving would cool down back to normal. This is my father’s car as has been occurring for nearly a month now. He said it only overheated to where he had to pull over and let it cool down once. I checked it the last time it over heated, looked for leaks seen none, checked fluid level was topped off and he said it was a while since he added any coolant. I checked the fan operation and it appeared to be kicked on when it was supposed to. I checked the hoses and it seemed like heat disbursement was equal. I also checked the radiator for cold spots and felt none. I don’t know if the car has actually over heated or if my dad just pulled off because the gauge was showing it was red lining. I attempted to check it with coolant pressure tester but I didn’t have the proper adapter to check it as it is the place threaded neck style on the reservoir. One last thing the oil seems clean notice no signs of coolant in the oil or that coolant is being burned in the chamber.

My second problem is the more prominent one. This occurred the day after I checked it out for it’s overheating problem. We were driving down the interstate and the vehicle just died it didn’t sputter or anything it just all of the sudden had no power, lights and everything were on. We pulled to the side of the road and it restarted right away we went an addition 10 miles or so and then it died again this time sputtering bad. Initially I pulled one of the spark plugs and checked for a strong blue spark which I was getting I also put a pen in the fuel rack check valve to check for adequate fuel pressure it seemed to be a strong pressure. I took over the wheel and keep my foot on the gas peddle the whole time as when I would let it idle it wanted to die. I was able to coast home before it died completely and wouldn’t start. I wasn’t able to look at it again until a few days latter I checked all for cylinders for good spark and was getting a good spark and seemed in time. I then check for fuel pressure at the fuel rack and was getting 40lbs of pressure at the fuel rack. The vehicle wouldn’t start although when I sprayed it with starting fluid it started right up initially I was thinking the crank sensor was sending the signal to the ecm to be relayed the injectors. However the next day after I got out of work I went to read an engine code as the engine light had come on before. I got no code just 12 the beginning code. So I tried to start the vehicle to retrigger the code to come on. It started a little rough but ran until I put my foot on the gas peddle and then it would die I did this several times it would start and then die as soon as I put my foot on the gas peddle. After the forth try I let it build up for a little bit until it seemed to be running smooth and then revved it up no problem at all it seemed to be running fine I ran it for a while trying to get it to act up again. I turned it off and restarted it about 10 times with no problem and it seemed to rev fine although it did seem like the peddle at a second or two hesitation as far as me revving the motor and then taking my foot off the peddle till the time it came back to an idle position.

This is my dad’s car and he doesn’t have a whole lot of money and this is not something I want to throw parts at.

I thought one of two things based on dieing and then starting back up, I was thinking that the ignition control module may be failing when it gets hot. I was going to take this off and test it for a while to get the part hot and see if it fails. The other thing I was thinking is probably the most obvious I think the fuel pump may be failing intermittently. I was going to replace the fuel filter and the thermostat relating to my previous problem for basic maintenance and possible trouble spots. Like I said before originally I was thinking I had a bad crank sensor but I am doubting that explanation now. As far as my first problem with this car I was thinking the propeller blades on the water pump have worn as I don't hear a bearing squeal and don't see any leak at the weap hole.

I was a diesel mechanic for about 7 years so I have a pretty good mechanical knowledge but semi trucks are a little different beast and am not knowledgeable on every single model of car and what problems they tend to have.


Answer
Problem 1 would be to change the thermostat and flush the cooling system.Possibly the vanes on the pump but more likely the thermostat.It could also be a small leak in the head gasket which will cause overheating at idle.If the car starts to overheat ,turn on the heater full and see if the temp drops.Thats a good sign of a bad thermostat and the cooling system needing cleaned out.The stalling problem sounds like the fuel pump but look at the module also as its possible to have it tested and eliminate that.Good spark at the plugs will mean you have a fuel problem.99 times its the pump but do the usual tests on the relay and fuses first.You will need to hook up a fuel pressure tester and watch the pressure as the car is running because the pressure must stay constant at 40 psi approx.If it drops or varies then the pump is going out.Its all elimination as you know and there are other things that will cause the engine to die like the fuel pressure regulator and MAF sensor EGR , so best to get a manual and go through the procedures.Finally take off the crank sensor and clean it.A bad crank sensor is usually a no start at all situation but clean it anyway.