Oil pressure specs?

OK, before anybody bitchs about the subject not matchin the post, look at the time stamp. I wasn't awake yet.

Fuel pressure is what I need. Thanks.

On Fri, 11 Dec 2009 04:33:10 -0600, Old Crow rearranged some electrons to say:

Not sure about the Ranger, but for my old F150 I believe it is around 40 psi.

Fuel Pressure is driven by two things, the output of the pump, and the pressure regulator.

Let's say, for example, the pump delivers 60psi (which I _think_ is about right, but I do not know for certain), but at idle and low speed, the injectors only need 20psi to deliver enough fuel, the regulator diverts the extra fuel back to the gas tank to begin the cycle again. As the vehicle loads demand more fuel be delivered, the regulator shunts less of the 60psi back to the tank, and more fule is consumed by the injectors.

Think of clogged pipes in your house. You turn on the hot and cold, mix the water to get what you need, climb into the shower and start to soap up. Somebody flushes a toilet, and your shower goes to full hot in an instant and remains until the water pressure sbatalizes again. The fuel pump is delivering the cold water, but the pressure is low so any new demand that comes along robs cold water and causes only the hot to remain. The analogy isn't true, but it does illustrate the point, the fuel pressure is a constant, and is always greater than the demand. Sometimes the fuel pressure is much greater than the demand and at other times it is marginally greater than the demand.

I recall that the engine needs about 45psi of fuel at full demand, and the pump should deliver greater pressure than the demand calls for, so there is a regulator that dictates what the actual operating pressure is.

If you end up replacing the fuel pump on the truck, the easy way is to remove the bed and expose the gas tank. There are 6 or 8 bolts holding it down, and a wire harness for the brake lights. Two guys can lift the bed off and rest it on the tires. I replaced a fuel pump on a Chevy Silverado a couple of weeks ago by myself. I removed 4 screws on one side of the bed, and loosened the 4 on the other side, then lifted the bed and placed a jack stand under it to hold it up. The gas tank was exposed, and the pump came out easily.

Thanks Jeff. I don't recall if I ever mentioned it here or on the Jeep group, but I spent 19 years as a tech at GM dealerships until about 4 years ago when I got a job restoring classic cars and building street rods. We just don't have a book at the shop for anything as new as '96, and the service manager at the local Ford shop and I don't get along, so I couldn't call and ask. As it turns out, his wife won't let him have the truck today, anyway, so it'll have to wait a week or so.

Why are you looking at the fuel pump? Most people never suspect the pump has failed until after they call the auto club to come get the vehicle and drag it home or to the shop. Weak pressure seldom is noticed, and by the time the tow truck comes around the pump has failed.

My '95 Bronco never gave any indication that the pump was going out, and it failed in my driveway -- saving a call to the auto club -- where the symptom was that the engine fired for a few seconds then shut down. I had an OBD I Code Reader that told me the pump had failed. I told you earlier that I replaced the pump in a Silverado recently, I have an OBD II Code Reader, but there was no code for the failed pump.

While you're working on that Ranger, yoiu shoujld be prepared to replace the Fuel Filler Hose too. My Dad and brother both have a Ranger and the hose failed on them -- caused the truck to fail the Smog Inspection.

Actually, I'm beginning my trouble shooting there. A couple of months ago he changed his own fuel filter when the truck wouldn't start in the driveway. Said the filter was full of mud. Now he says the truck is running just like it did before it wouldn't start. I've seen plenty of GM pumps die because of plugged filters, so I told him I'd check it out. Also brought home a compression gauge, a set of Noid lights and a multimeter just in case it's something else. Dude's unemployed and can't afford to take it to the shop and I was just trying to save him a buck or several.