Lift Pump?

[fastcat800]

I tried to drain water and when I open the valve I get nothing until about four or five turns and then the truck dies (no water or fuel out the line). Must not be any pressure. I have to crank for about a minute to get it started and it idles very rough now and then dies. Is the lift pump the thing that looks like the inline filter with wires running to it on the frame rail under the drivers door? When does it run on the '94's? When you turn the key on? Is it continuous or is there an internal pressure switch that turns it off and on? Any tips on replacement? I just filled the tank with fuel. I want to test it to see if I am getting power to it before I replace it.

[fastcat800]

See the misfire under power thread.

[curmudge1]

On my '94 Blazer 6.5TD, the way I can run the pump when the engine is off is to take the cover off the fuse block mounted on the firewall in the engine compartment, then take the lead (fuse) for the pump & touch it directly to one of the 'hot' posts. I.e., you're touching the fuse directly to the hot terminal. You'll hear the lift pump run immediately, if it's not dead. HTH.
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David Strom