Odd No Start Problem
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Junior User
Joined: Nov 2012
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Odd No Start Problem
Hey guys I noticed the other day if my glow plugs are on for more than like 10 seconds the truck won't start. Is this normal? It's about 70 degrees here this week. Any suggestions or thoughts?
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Junior User
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Yes. It will start no problem even if I wait for the light to go out. But once it's off and I wait like 10 seconds or so it will just crank and crank but will not fire. Then I shut it off and turn the key don't wait and it fires right up.
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Rich, so once fuel pressure is at optimum, does that trigger pump shut-off or is it a timing function?
It would make more logical sense for the pump to be controlled by the PCM input from the fuel pressure sensor and a timeout feature. If that sensor is faulty or slow from plugging up or just beginning to fail, the pump could be erratic during start-up.
Once the engine is running, the demand for fuel would keep the pump running because the PCM timing cycle would not initiate due to the engines need for fuel. I believe that the pressure sensor is more likely to fail than the timer in the PCM. The fuel pump relay cannot be the problem, because Nick's description shows that the pump's operation is very predictable.
Larry
It would make more logical sense for the pump to be controlled by the PCM input from the fuel pressure sensor and a timeout feature. If that sensor is faulty or slow from plugging up or just beginning to fail, the pump could be erratic during start-up.
Once the engine is running, the demand for fuel would keep the pump running because the PCM timing cycle would not initiate due to the engines need for fuel. I believe that the pressure sensor is more likely to fail than the timer in the PCM. The fuel pump relay cannot be the problem, because Nick's description shows that the pump's operation is very predictable.
Larry
Lead Driver
Joined: Jun 2004
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From: Amarillo, TEXAS!
There is no fuel pressure sensor. The pump runs for 20 seconds when the ignition is turned on. If the engine is started after that time, the pump should restart when the engine is cranked. If the fuel system is in good order, there should still be residual pressure in the fuel filter housing for a couple seconds after the pump stops running. IIRC, as a safety feature, the FPR has a small orifice in it to bleed off pressure slowly after the pump stops to make it harder to remove the filter cap while the housing is still pressurized.
If the fuel pump circuit is commanded on by the PCM, and power is not detected, you should get a P0231 DTC. A quick test would be to turn the key on and listen for the fuel pump to run for 20 seconds. After it times out, quickly bump the key to start without turning it off first. The fuel pump should restart and time out again after another 20 seconds.
If the fuel pump circuit is commanded on by the PCM, and power is not detected, you should get a P0231 DTC. A quick test would be to turn the key on and listen for the fuel pump to run for 20 seconds. After it times out, quickly bump the key to start without turning it off first. The fuel pump should restart and time out again after another 20 seconds.
Lead Driver
Joined: Jun 2004
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From: Amarillo, TEXAS!
It runs by default at key on and any time RPM is detected, so it seems the camshaft position sensor signal is in play. It would be kind of interesting for the next person who has a bad cam sensor to try the starter bump and see if the pump restarts after it times out.
Cargo Master
Joined: Oct 2010
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Its reaching and would require a lot more thought & schematic chasing than I have right now but what about the collapsing field of the GPR causing either IDM or PCM relay (because of a bad diode) to quit working. It would cost nothing to check as you could swap one with the blower relay and keep swapping until you know that they have all been through each hole. Of course, you could check the diode in the relay with VOM as well.