Mechanics

WHY WILL MY 2001 START AND RUN FINE UNLESS IT IS COLD OUT

1991 Saturn SC1

I have a 2001 Saturn and it start and runs great when warm outside but when it gets below 50 it will cranck but wont start
we have changed the spark plus and pulg wires allso the coolpack and idk what all else please help


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Kristencupp
December 28, 2011.



Have you checked the coolant temp sensor and connector?That sounds like the best place to start.

Saturntech9
Dec 28, 2011.
Here is everything we have tried
fuel injectors
crankshaft sensor
egr valve
oxygen sensor
mass air flow
coolant temp sensor

Tiny
Kristencupp
Dec 28, 2011.
Could it have anything to do with the fuel pump?

Tiny
Kristencupp
Dec 28, 2011.
That car doesnt have a mass airflow sensor. Which coolant temp sensor did you replace?The top one with one wire or the bottom one with two wires going to it?Also did you inspect the inside of the connector to see if the terminals are silver and not green or blue?Those coolant temp sensors leak coolant into the connectors corroding terminals causing the sensor to miss read.

Saturntech9
Dec 28, 2011.
I ment the map sensor. And yes my husband tested and replaced both of them

Tiny
Kristencupp
Dec 28, 2011.
The top one with one wire runs the gauge the bottom one with two wires is for the computer. Are you sure he inspected the connectors?Also you have to make sure you replace the bottom one with the correct sensor.I have seen people get the wrong bottom coolant temp sensor and that causes issues. Most of the time when I see cold start issue on those cars is a coolant temp sensor issue. Try this next time it wont start try holding the gas pedal all the way to the floor while starting it see if it starts that way. Also when its hard to start and it finally starts does black smoke ever come out of the exhaust pipe?Any trouble codes?Have you checked for codes yet?

Saturntech9
Dec 28, 2011.
No codes show and yes black smoke when it does start but just for like a sec and yes we have changed them both does the water pump have anything to do with it

Tiny
Kristencupp
Dec 28, 2011.
The water pump has nothing to do with it the black smoke is another thing you see with a coolant temp sensor issue. It totally sounds like a temp sensor issue. You dont have a scan tool that can read live data on that car like coolant temp etc?

Saturntech9
Dec 28, 2011.
He bought a tester thing and we took it to the garge and no codes showed at all we changed them and it ran for awhile and quit agian

Tiny
Kristencupp
Dec 28, 2011.
What is the dif in the two sencors

Tiny
Kristencupp
Dec 28, 2011.
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