7.3 won't start cold
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7.3 won't start cold
New batteries, new glow plugs, new gpr. Truck still will not start below 40 degrees Fahrenheit. What else can I do or check to get the truck to start better. It fires and wants to start and after a lot of cranking sessions it will but the batteries usually don't hold up long enough. What else can I check?
Cargo Master
Joined: Feb 2010
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From: Delta, CO
If all that is new I believe you have a wiring problem, the glow plugs must not be getting power. I'd start at the GPR & make sure the wires to glow plugs are getting close to 12v & go from there. You may have to pull valve covers and make sure the glow plugs are getting power.
Cargo Master
Joined: Oct 2007
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From: BoCoMo
If all that is new I believe you have a wiring problem, the glow plugs must not be getting power. I'd start at the GPR & make sure the wires to glow plugs are getting close to 12v & go from there. You may have to pull valve covers and make sure the glow plugs are getting power.
Cargo Master
Joined: Oct 2007
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From: BoCoMo
New batteries, new glow plugs, new gpr. Truck still will not start below 40 degrees Fahrenheit. What else can I do or check to get the truck to start better. It fires and wants to start and after a lot of cranking sessions it will but the batteries usually don't hold up long enough. What else can I check?
1) this will tell you of your voltage of batteries before key turned out ....around12.5v
2) turn key on 'wait to start' Glow Plug should come on and voltage will drop....around/above 11.5v. This will tell you that your GPR and 'most' glow plugs are working. no drop, no GPR...
3) 'wait to start' light goes out, hit key for only 2-3 seconds at a time when trying to start... voltage will drop around above 10.5v witth the starter engaged. 'If' the voltage drops below 10.3v, the truck most like will not start. Remember that the Glow Plugs will stay on for a minute or so after the 'wait to start' light goes out.
4) When (if) the truck starts the voltage will be 'around' 11.5v, as the glow plugs are still on.
5)You know when the Glow Plug Relay shuts off (truck running) when the voltage will SLOWLY start to rise on the voltage meter.
6) The voltage will slowly rise to the out put of the Alternator. (should be 'around' above 14v.)
The power port voltage meter tells you a lot in a short amount of time in what is going on with your starting and charging system.
Cargo Master
Joined: Oct 2007
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From: BoCoMo
Another thing to think about is to change your oil to a thinner oil velocity. Oil pressure opens up the injectors to pump fuel into the cylinders. If the oil is too 'thick' from the 'cold', the injectors may have an issue in opening up. one way to 'check' on this is to 'plug in' your engine block heater about two hours before you try to start it. If it fires right up with the 'thinner/warmer oil', this may be the direction that you need to go.
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tobeki
1987 - 1996 F150 & Larger F-Series Trucks
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May 11, 2009 06:53 PM
