helpful hints

[d.h.]

Should lift pump operate with key in "ON" position? I was on the understanding it would not run without oil pressure.That has been the way I,ve been getting fuel to filter after changing.Turn the key on and wait for clear fuel.A mechanic I took it to told me this was how to do it.Is this a sure fire way to burn out lift pump as I,m thinking this is whats causing my intermitant miss. I,ve done a lot of "searching" but maybe someone could point me in right direction.Also with truck at idle if you open the bleed on top of filter should fuel spurt out or just kind of run out slowely Thanks for your patience as I will learn some of this eventually :D

[diesel1995]

As far as the procedure to bleed the fuel filter, the one i use is very easy.

1. Open the bleed valve
2. Turn the key to on position
3. Put the truck in gear
4. Hold the key to crank position

This will run the lift pump indefinitley without cranking the engine.

You are correct, the lift pump will not run with the key in the on position without oil pressure to the pressure switch.

With the truck running, if you open the top of the fuel filter, it should be a small stream, not a spurt, but not running out very slowly ... pressure provided from the lift pump is very small. The injector pump is where the real PSI magic happens.

As far as your intermittent engine miss, there are a few possibilities:

1. Faulty Injector or Injector Pump, will eventually become a consistent miss.
2. The first signs of a failing FSD, will eventually become a stall, no hot-start condition.
3. Air in the Fuel - Who can say? smile.gif

I would attend to these in the reverse order i have given them to you.

Jake

[MTTwister]

Know from nuthin - but I'm under the impression that starting in '96, the lift pump runs during the glow plug cycling.

[Turbine Doc]

Actually in the 98 the pump will run for length of the glow cycle & key on, you may have to do multiple key on key off for full bowl fill.

I doubt the pump will go bad from this, unless your tank is dry and no fuel actually going thru it; the lift pump doesn't care if it's feeding your driveway from the bowl vent or your IP at full throttle.

The test to see if the pump is outputting properly per the manual (paraphrased) is open filt bowl drain, place cup/bucket under it key on and measure fuel collected over time 1/2 pt in 15 sec. is a good pump.

[bigcontender]

With the truck running connect a pressure gauge to the water separator drain hose. Open the vent and check the pressure, my 96 runs 10 1/4psi which I was told is very good. Easy test once you set up a gauge with hose barbs and a short fuel hose of the right size.

[d.h.]

Thanks for replies. I will try some of these suggestions and see what happens. I,m hoping its not i/p.