I've got my '97, XLT, 4.2L, 5sp up for sale. It sat for almost 2 weeks without starting it. And it was on a slight incline. When I started it last, the oil pressure light and needle were in trouble. I rolled it off the hill and the needle finally came up to normal. But, when I reved the engine, it would dip again. And if I rolled backwards and jammed on the breaks, the needle would dip. I took it for a ride again last night, and it seems to be better, but the needle is still bouncing. There is no oil leaking, the engine is staying cool, and it is purring like a kitten. I don't think the oil pump lost prime...could it just be a bubble behind the sensor? Any ideas on how to fix it?

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Deep Blue 2000 XLT, 4wd, 4.6L, Automatic, SB, SuperCab, Norfalk Plant, DP Box

 

You might want to do a search on "oil pressure guage". You will find that the guage is nothing more than an idiot light(guage). It does NOT read true oil pressure, it is a semi resistive electrical switch that as long as it has at least 4psi of pressure it will read somewhere in the middle of the normal range. So if being parked on an incline somehow reduced pressure at the sendeing unit then your guage may have read low. Otherwise it is more likely an electrical problem. With the bouncing you mentioned I'd say the sensor is bad.

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99 XLT,4.6L Auto,4X4,tow pkge,Factory Side Steps and Mudflaps, K&N filter,BugflectorII, Amazon Green/Silver, Pace Edwards Rolltop Cover, still want a Superchip and by golly I'm gonna get one (just as soon and I hit the lottery )

 

Thanks for the reply! I did the search and learned just how reliable that "gauge" is. I haven't had a chance to check it yet...but, I'm betting it's either a loose connection or a bad sensor. Otherwise, why would it bounce like that. It should either be on or off.

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Deep Blue 2000 XLT, 4wd, 4.6L, Automatic, SB, SuperCab, Norfalk Plant, DP Box

 

I'm not saying this to be a wise guy but, have you checked the oil level lately. My friend had a Maverick that did the same thing and he was a couple of quarts low.

Just a thought--Bob

 

Yeah, I checked the oil level. It was the first thing I checked, actually. I'm pretty sure its electronic.

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Deep Blue 2000 XLT, 4wd, 4.6L, Automatic, SB, SuperCab, Norfalk Plant, DP Box

 

One thing to add...

Check the oil pressure with a real gauge, to confirm. I couldn't find the oil pressure for the 4.2L - They omitted it from the factory manuals. ANyway, a rule of thumb for a stock engine, is that you should have ~1PSI of oil for every 100rpm. i.e. 1500rpm ~= 15PSI.
The bearing clearances are probably similar to a 4.6 & 5.4. If they are, you should be getting 40-70 PSI at 1500RPM, HOT. My 5.4l is ~65 at1500rpm, HOT.

Hope this helps.

Tony

[This message has been edited by F150Tony (edited 10-20-2000).]

 

Thanks Tony!
I'm hoping to go by and check out the truck this afternoon. I'm going to start with checking for a loose connection somewhere. If I don't get anywhere, I'll proabably end up bringing it into a dealer. I've still got an ESP on it, so, no need to fool around too much.

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Deep Blue 2000 XLT, 4wd, 4.6L, Automatic, SB, SuperCab, Norfalk Plant, DP Box

 

Problem fixed...just a bad sending unit. ESP covered it.

Thanks for all of your input!

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Deep Blue 2000 XLT, 4wd, 4.6L, Automatic, SB, SuperCab, Norfalk Plant, DP Box