So i picked up a ranger for cheap because they said it had a blown head gasket. took the head off and seen a cracked piston replaced a lot of bottom end parts including oil pump, honed cylinders, and a good cleaning. I've now got it all back together and in the truck, the timing is good and it starts up but is getting no oil pressure at all. runs for like 2 seconds then dies out. put an oil pressure tester on it and it shows zero. any ideas as to why the pump is not pulling oil?

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2000 Ranger/ 2.5L/ Automatic

Did you prime pump when you installed new? Fill it with grease? A dry pump will not pump oil. I'm not sure how those pumps are driven.

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2002 4.0 4x4 auto.
Black Rock steelies, 32" Cooper Discover AT/3
Power leather buckets, Full length console
EATC, OHC, Lighted visors, Wite cluster
>CLICK<

I do not know the specifics of the 2.5, but with both my 2.0 (pump is down in the pan area) and 95-era 2.3 (pump is directly driven off timing belt, may be similar to 2.5), when completely dry, the pump was able to self-prime but took about 4 seconds of runtime and the starter could not crank it fast enough to make it happen. Unlike some other designs e.g. SBF, the oil pressure sender is almost all the way at the farthest part of the oiling system on a Lima, so you won't see anything until the oil has been distributed pretty effectively.

If you can't get the engine to run more than 2 seconds or so, I will call it normal not to see oil pressure. It is of course preferred that you prime the oiling system but there are various reasons that might not be practical.

OTOH - if the 2.5 is like the 2.3 Lima with respect to the oil pump being right on the timing belt, you could pull the belt and spin the pump quickly with something (impact? but the hammering would not be ideal) and see if it builds oil pressure that way. You'd accomplish two things: 1, verifying you can actually get oil to pressurize and 2 priming it so the next start attempt isn't dry.

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'85 2.0>2.3 5-speed

Take out the sparking plugs. Do not run the engine at all under power until you have developed oil pressure.
As I understand it, the pump is driven by the auxiliary shaft, the third sprocket on the front of the engine. As suggested, you may be able to spin the aux sprocket enough to get the oil galleries filled and pressurized without cranking the engine. That would be the best thing to do to avoid load & possible bearing damage by rotating without lube being supplied.
I think you can remove the pump, and pack it at least partially with grease(Vaseline works well) to insure there is good internal sealing and the pump can pull oil from the sump.
You might be able to use a 'sanding disc' on a hand drill pressed against the aux sprocket to spin it enough to develop oil pressure. You do not have to have the belt in place to do this, and it would be best to have the belt removed from the aux sprocket. You might be able to rotate with the belt in place, but I would not.
The oil pressure switch it up on the drivers side of the cylinder head, close to the rear. Oil comes up around one of the head bolts to supply the cam followers and cam bearings.
tom

Thank yall! Turns out i hadnt primed the oil pump right. Read about how to do it and it did not work haha. Got oil pressure now

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2000 Ranger/ 2.5L/ Automatic