Hard start in cold weather
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Joined: Oct 2012
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Hard start in cold weather
I have posted about this problem before but here we go again. The truck is cranking and the engine is turning over but not firing, i can here the fuel pump kick on when i turn the key to the on position. Since it has been getting colder (low 20's to high 30's) it has been acting up. I had class this morning and had only let the truck set for about 45 mins and came out to leave and it just wouldnt fire, but after a couple of times of cranking it started right up and drove fine. It will also fire up but will be real weak and bog down and stall. Then went to put gas in it (while engine was hot) and went to fire it up and it just cranked. Has anyone had this happen and figure out what it was? i took it to my mechanic and it never acted up for them, i usually do all the work on my vehicles so if anyone can help, please do. thanks for any replies
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Unless some testing is done you will keep going round and round with the hassle.
First thing is to test fuel pressure if there is no CEL on.
The cold start sequence is complex. If one item is causing an issue you will have a problem.
Have you tried your spare key in case it's a PATS issue.
BTW what is the year and engine?
Good luck.
First thing is to test fuel pressure if there is no CEL on.
The cold start sequence is complex. If one item is causing an issue you will have a problem.
Have you tried your spare key in case it's a PATS issue.
BTW what is the year and engine?
Good luck.
Lead Driver
Joined: Sep 2006
Posts: 7,907
Likes: 143
Put a pressure gage on the test port.
It needs to be in the 35 psi range and increase 4 to 8 psi with the motor running as you remove the vacuum from the top of the regulator.
On cold starts the PCM looks at the value of the cylinder head or coolant temp and the intake air temp sensors when the ignition goes to run.
This also starts the fuel pump running for a second or two then stops.
When you crank, the PCM starts the fuel pump full time, the IAC is opened up and fuel is richened for the cold starts.
This may be fuel presure, the IAC stuck closed etc.
No use in trying to talk it into a fix.
Do the work and find out why there is an issue with the whole sequence.
For a shop to say it runs and can't find the problem is cause to question why you brought it to them to begin with.
If no attempt is made to do testing and try to find the cause, enjoy the hassle it provides.
Good luck.
It needs to be in the 35 psi range and increase 4 to 8 psi with the motor running as you remove the vacuum from the top of the regulator.
On cold starts the PCM looks at the value of the cylinder head or coolant temp and the intake air temp sensors when the ignition goes to run.
This also starts the fuel pump running for a second or two then stops.
When you crank, the PCM starts the fuel pump full time, the IAC is opened up and fuel is richened for the cold starts.
This may be fuel presure, the IAC stuck closed etc.
No use in trying to talk it into a fix.
Do the work and find out why there is an issue with the whole sequence.
For a shop to say it runs and can't find the problem is cause to question why you brought it to them to begin with.
If no attempt is made to do testing and try to find the cause, enjoy the hassle it provides.
Good luck.
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