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Old 03-05-2012, 09:34 AM   #14
fdryer
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Join Date: Jan 2006
Location: NYC
Posts: 39,535
 

2003 L-Series 3.0L Sedan
Default Re: My Saturn 2000 won't start. Security Light, Gas gauge not working.

The pcm B+ fuse powers the pcm only. If the pcm is dead then no EFI system, period. Its rare for the pcm B+ fuse to blow so its understandable that it was missed. Its always best to keep things simple before going technical. There's a separate pump fuse for the pump.

When there's any possibility of running the pump empty for any reason, refilling with as little as a gallon or two will be more than sufficient to allow the pump to build up pressure. The build up of pressure does two things; supply fuel to the injectors and eliminate any air in the system. When pressure builds above 20-30 psi (approximately) any air in the lines becomes compressed and quickly leaves the moment the engine is started. If a cough is heard on first start up, that may be the only indication of any air in the system as no air will remain as the engine warms up. Any worries about air is quickly dispelled as soon as the engine is started and run. Normal fuel pressure will be anywhere from 45-60 psi, depending on model, high enough to eliminate any air in the lines. No air will ever affect the EFI system as long as a gallon is at the bottom of the tank. Tank construction ensures fuel settles at the bottom where the fuel sock will strain water from fuel while still supplying fuel to the last drop. Most of us never let the tank run completely dry so the fuel pump system will not heat up and croak just because of one or more dry tanks. There will always be some fuel left whether the pump is surrounded in fuel or not. Heat isn't a factor in these pumps. No one has ever proven a pump burning out (new ones, not old ones) from running a tank dry several times. Pumps stop running the moment the engine stops, period. They do not run continuously with the ignition ON.

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