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[teamroper60]

Originally Posted by kraftchick

Teamproper....I definitely can appreciate the opinion. I too would really really like to know what is causing this. Even if a tuner safely gives me what I need, in the back of my mind it will still be driving me crazy not know what the real issue is. I did pull out the secondary fuel filter, siphoned the bowl out and tested fuel delivery to the bowl at KOEO....it filled up in about 2 secs. So it appears delivery from the tank to the bowl is okay. I don't know how to test it further from there as I am guessing from that point to the injectors is the fuel pressure you are referring to. How does one go about testing that, and does one of the sensors monitor that? If there is a sensor, of course it could be bad and giving a false positive reading to a computer monitoring that parameter. But how would I test it or get it tested to gaurantee that is or is not the problem. Also...if fuel pressure were low, causing lack of power, I'm assuming (maybe incorrectly) that this would mean there simply isn't the volume of fuel being delivered to the cylinder that it needs....seems this would make great fuel mileage....however I get 12.5 average around town...and 9 towing on my last outing (flat land).

The fuel flow from the factory pump to the fuel bowl is not regulated, so even a weak pump could probably fill the fuel bowl pretty quick. However you are incorrect in presuming that low fuel pressure/volume would increase fuel mileage. It will have exactly the opposite affect.

As stated, there isn't a fuel pressure sensor on these engines. Shoulda been, since low fuel pressure kills injectors in a hurry. This is why I always recommend a fuel pressure gauge be installed on these trucks.

There is a test port on the fuel bowl, just to the left of the return line. A fuel pressure gauge can be hooked into the system there to test pressure but you need to have enough line to get the gauge to a place where you can see it when the engine is under a load. If your pressure drops below 45psi, your pump or your regulator is bad.