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Too close to Raleigh, NC | The mechanical 12 valve injection pump (Bosch P7100) can pull enough fuel to lubricate itself and still move the truck down the road with a dead lift pump - the 24 valve will fry the VP44 injection pump if the lift pump dies. If you think the lift pump is going bad then check the fuel pressure at the inlet banjo. If you have over 20 psi at idle then your pump and relief valve is OK. If less than 20 and pinching the fuel return line closed raises the pressure a couple of psi then the relief valve is shot.
On my 96 I always use the lift pump button to prime the fuel filter to keep any potential for contaminated fuel out of the injection pump. Takes about 20-30 strokes to get it full. I use a piece of 2X2 deck rail upright with a 45* cut on the end to reach it. Cut short enough to get under the brake master cylinder. 45* makes good contact with the primer bulb. Not the easiest to stretch down there with a thumb, and it takes a thumb when the pressure starts building up. | |
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5.9 Liter Cummings
