Motor wont start if Temp is below 40F°
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Registered User
Joined: Feb 2011
Posts: 11
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From: MTY
Motor wont start if Temp is below 40F°
My truck has been giving me a headache when weather temp. drops below 40 .
which could be the problem it has a new gas pump so gas is not the problem ,has new battery Dist. cap and it is always the same problem
just as the weather temp starts to go up 41+ the motor will start perfect .
which could be the problem it has a new gas pump so gas is not the problem ,has new battery Dist. cap and it is always the same problem
just as the weather temp starts to go up 41+ the motor will start perfect .
Hall Of Fame
Joined: Jul 2006
Posts: 12,204
Likes: 10
From: Gainesville, Ga.
first simple test. swap the ASD and fuel pump relays with something like horn or wiper. its in the pdc box beside the battery.
second simple test. try pressing the gas pedal while cranking. this opens the closed throttle plate and bypasses the IAC idle control.
check for fuel pressure at the test port on the rail and spark at the plugs.
the low tech way to check fuel pressure is to turn the key to on, wait about 5 seconds, then turn it off. find the test port on the fuel rail drivers side. it looks like a tire valve. hold a rag over it and press the center pin. if gas squirts out under what seems like 49 psi, then your fuel pressure is probably ok. do not smoke while doing this or you'll have a much more serious problem.
if fuel is ok, give it a squirt of starting fluid just to be sure its not fuel related.
if fuel is ok, check the electrical for 12v at the coil and/or spark at the spark plugs.
report back.
second simple test. try pressing the gas pedal while cranking. this opens the closed throttle plate and bypasses the IAC idle control.
check for fuel pressure at the test port on the rail and spark at the plugs.
the low tech way to check fuel pressure is to turn the key to on, wait about 5 seconds, then turn it off. find the test port on the fuel rail drivers side. it looks like a tire valve. hold a rag over it and press the center pin. if gas squirts out under what seems like 49 psi, then your fuel pressure is probably ok. do not smoke while doing this or you'll have a much more serious problem.
if fuel is ok, give it a squirt of starting fluid just to be sure its not fuel related.
if fuel is ok, check the electrical for 12v at the coil and/or spark at the spark plugs.
report back.
Thread Starter
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Registered User
Joined: Feb 2011
Posts: 11
Likes: 0
From: MTY
first simple test. swap the ASD and fuel pump relays with something like horn or wiper. its in the pdc box beside the battery.
second simple test. try pressing the gas pedal while cranking. this opens the closed throttle plate and bypasses the IAC idle control.
check for fuel pressure at the test port on the rail and spark at the plugs.
the low tech way to check fuel pressure is to turn the key to on, wait about 5 seconds, then turn it off. find the test port on the fuel rail drivers side. it looks like a tire valve. hold a rag over it and press the center pin. if gas squirts out under what seems like 49 psi, then your fuel pressure is probably ok. do not smoke while doing this or you'll have a much more serious problem.
if fuel is ok, give it a squirt of starting fluid just to be sure its not fuel related.
if fuel is ok, check the electrical for 12v at the coil and/or spark at the spark plugs.
report back.
second simple test. try pressing the gas pedal while cranking. this opens the closed throttle plate and bypasses the IAC idle control.
check for fuel pressure at the test port on the rail and spark at the plugs.
the low tech way to check fuel pressure is to turn the key to on, wait about 5 seconds, then turn it off. find the test port on the fuel rail drivers side. it looks like a tire valve. hold a rag over it and press the center pin. if gas squirts out under what seems like 49 psi, then your fuel pressure is probably ok. do not smoke while doing this or you'll have a much more serious problem.
if fuel is ok, give it a squirt of starting fluid just to be sure its not fuel related.
if fuel is ok, check the electrical for 12v at the coil and/or spark at the spark plugs.
report back.
Today :
I swap the relays as you suggested and didnt start
Gas pressure Ok
I pressed the gas pedal while cranking didnt start
Last year :
i got a accel coil for dodge and had the same problem didnt start
i tried starting fluid didnt start
The main problem here is that i depend on my truck couse of my bussines i have to carry tools thats why this truck gives me a headache in winter .
i think this is what may truck thinks of me in clold days
lolo
My truck has been giving me a headache when weather temp. drops below 40 .
which could be the problem it has a new gas pump so gas is not the problem ,has new battery Dist. cap and it is always the same problem
just as the weather temp starts to go up 41+ the motor will start perfect .
which could be the problem it has a new gas pump so gas is not the problem ,has new battery Dist. cap and it is always the same problem
just as the weather temp starts to go up 41+ the motor will start perfect .
Here's what I want you to do and, it's really simple. You're going to run a poor man's THERMAL CYCLING TEST on the PCM.
PROCEDURE:
REMOVE the negative lead (-) from the battery and wait 1-3 minutes for all power to bleed off to ground.
REMOVE THE COVER ON THE PCM.
REMOVE the THREE connectors at the PCM.
REMOVE THE PCM
TAKE THE PCM INTO THE HOUSE and allow it to warm to AMBIENT TEMP.
RE-INSTALL PCM INTO TRUCK
CONNECT THREE CONNECTORS
NOTE: MAKE SURE ALL power is off on the vehicle. NO lights are on, no radio is on, all doors are closed (DOME LAMP) is OFF etc etc PRIOR to connecting the NEG (-) BAT terminal.
RECONNECT NEG (-) BAT TERMINAL.
START TRUCK.
<IF> the truck turns over and it starts when PCM is at AMBIENT TEMP- you've got a failure at the PCM level and, most likely, it's going to be the ground control circuit and or COM. If this is the case, leave the PCM in the truck overnight and try to start it in the morning.
<IF> it does not start in the morning t AT COLD: repeat the above test for a total of five times to gain statistics in confidence level that a failure at the PCM level is indeed the root cause for failure and not a BAD CONNECTION. If it starts at AMBIENT TEMP all times, it's rooted at the PCM level.
<IF> the truck does not start under any of those tests, it's either going to be rooted in either the ignition or fuel delivery system level.
CM
Last edited by cmckenna; Feb 3, 2011 at 05:10 PM.
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Joined: Nov 2010
Posts: 85
Likes: 0
From: Tacoma Wa
This is common on some models due to a failure at the PCM level. I've now helped three people with this same failure mode- won't start at below X-temp.
Here's what I want you to do and, it's really simple. You're going to run a poor man's THERMAL CYCLING TEST on the PCM.
PROCEDURE:
REMOVE the negative lead (-) from the battery and wait 1-3 minutes for all power to bleed off to ground.
REMOVE THE COVER ON THE PCM.
REMOVE the THREE connectors at the PCM.
REMOVE THE PCM
TAKE THE PCM INTO THE HOUSE and allow it to warm to AMBIENT TEMP.
RE-INSTALL PCM INTO TRUCK
CONNECT THREE CONNECTORS
NOTE: MAKE SURE ALL power is off on the vehicle. NO lights are on, no radio is on, all doors are closed (DOME LAMP) is OFF etc etc PRIOR to connecting the NEG (-) BAT terminal.
RECONNECT NEG (-) BAT TERMINAL.
START TRUCK.
<IF> the truck turns over and it starts when PCM is at AMBIENT TEMP- you've got a failure at the PCM level and, most likely, it's going to be the ground control circuit and or COM. If this is the case, leave the PCM in the truck overnight and try to start it in the morning.
<IF> it does not start in the morning t AT COLD: repeat the above test for a total of five times to gain statistics in confidence level that a failure at the PCM level is indeed the root cause for failure and not a BAD CONNECTION. If it starts at AMBIENT TEMP all times, it's rooted at the PCM level.
<IF> the truck does not start under any of those tests, it's either going to be rooted in either the ignition or fuel delivery system level.
CM
Here's what I want you to do and, it's really simple. You're going to run a poor man's THERMAL CYCLING TEST on the PCM.
PROCEDURE:
REMOVE the negative lead (-) from the battery and wait 1-3 minutes for all power to bleed off to ground.
REMOVE THE COVER ON THE PCM.
REMOVE the THREE connectors at the PCM.
REMOVE THE PCM
TAKE THE PCM INTO THE HOUSE and allow it to warm to AMBIENT TEMP.
RE-INSTALL PCM INTO TRUCK
CONNECT THREE CONNECTORS
NOTE: MAKE SURE ALL power is off on the vehicle. NO lights are on, no radio is on, all doors are closed (DOME LAMP) is OFF etc etc PRIOR to connecting the NEG (-) BAT terminal.
RECONNECT NEG (-) BAT TERMINAL.
START TRUCK.
<IF> the truck turns over and it starts when PCM is at AMBIENT TEMP- you've got a failure at the PCM level and, most likely, it's going to be the ground control circuit and or COM. If this is the case, leave the PCM in the truck overnight and try to start it in the morning.
<IF> it does not start in the morning t AT COLD: repeat the above test for a total of five times to gain statistics in confidence level that a failure at the PCM level is indeed the root cause for failure and not a BAD CONNECTION. If it starts at AMBIENT TEMP all times, it's rooted at the PCM level.
<IF> the truck does not start under any of those tests, it's either going to be rooted in either the ignition or fuel delivery system level.
CM
hope it works for ya. bet you would not have guessed this one.
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Hall Of Fame
Joined: Jul 2006
Posts: 12,204
Likes: 10
From: Gainesville, Ga.
^^ i wonder how well it would work to use a hair dryer to blow hot air on the pcm for about 5-10 minutes to accelerate the warm up period without removing it from the truck. just get it warm, not hot.
to the OP, did this problem start with the Accel coil? if so, blow warm air on it too... then replace the damn thing.
since the stating fluid didn't help, i'd focus on electrical too.
to the OP, did this problem start with the Accel coil? if so, blow warm air on it too... then replace the damn thing.
since the stating fluid didn't help, i'd focus on electrical too.
Administrator
Joined: Apr 2010
Posts: 87,548
Likes: 4,230
From: Clayton MI
I don't think a hair dry would be able to get it too hot.... or at least, you would have to be trying awful hard. It does hang out in the engine compartment after all. Not precisely a pleasant environment.