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Greg, Technician
Category: Pontiac
Satisfied Customers: 7126
Experience:  17 years Shop Owner /Technician. 27 years experience,
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Car runs until you shut it off, wont restart until its cold

Customer Question

Hi car runs until you shut it off, wont restart until its cold or colder. 2003 montana
JA: Are you fixing your Montana yourself? What have you tried so far?
Customer: yes
JA: Anything else you want the mechanic to know before I connect you?
Customer: I purged the air from the cooling system and it worked right for a few days
JA: Has the car been overheating? Have you noticed any leaks?
Customer: no, except it had fan problems and I pulled the ect, fans ok. it had a leaking water pump I repaced it
Submitted: 1 month ago.
Category: Pontiac
Expert:  Greg replied 1 month ago.

Hi, I'm Greg (Indy-Tech).
Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP.
Rgds Greg.

Expert:  Greg replied 1 month ago.

Hi .

This is a very common issue that you have ,see this just about every other month in my shop and in 95% of the time its just a bad crankshaft sensor .

This is located just behind the crankshaft pulley ,so this will have to be removed to gain access to replace.

Quick test what you can do if you have a engine rev counter is when you have a no start period try and start and if the rev counter does nor show 250 +/-50 rpm the crank sensor is bad .

If you don't have a rev counter you will need a scan tool with live data and go to engine speed.

This is not a one answer and done i/we will stay with you until the problem is sorted out .
Before rating poor or bad please get back to me as i'm here to help you, if i can't i will opt out so another expert can.
We want you to be happy with an answer and help you with your problem . Want you to be a happy motorist .
After rating there is no further cost for any other question relating to this problem
Kind regards Greg..

Customer: replied 1 month ago.
I'm confused. I'm going to work on the car in the morning, then rate our outcome. is this ok? your fix makes sense. the ckp plug is very wet. I plan on hitting the plug with a can of pressurized dry air, then a dielectric..
Expert:  Greg replied 1 month ago.

Sure no problem rate when ready .

But just drying off the sensor and using dielectric will not help .

The problem is the sensor has malfunction internally when it get hot is fail ,when cools off it reconnect.

You will have to replace it ,but do the test as said above .

Rgds Greg

Customer: replied 1 month ago.
Expert:  Greg replied 1 month ago.

See if you can do the test first when she fails to start as other issue that can cause this same problem is the fuel pump

only when hot it will start and stall in most cases,

Then the coil when no start and you have RPM reading check for spark at the plugs .

Rgds Greg.

PS. Do the check for engine speed first as when the cranksensor fail you will also have no spark .

so if you have a rpm ready check spark if no spark replace the coil