Hey how y'all doing alright so on my 1994 f150 has 106,5xx miles on it and the check engine light is on with the oil pressure very low also something else not sure if it goes along with the problem but also when you give it gas in neutral and let off of the gas it goes down to about 500 rpm and looses some power but doesn't die have no idea what is going on please help!

 

welcome to FTE.

You may have more than one problem.

Faulty IAC maybe. If it's not properly controlling engine idle speed & it gets too low, it could turn the op light on, or you could get a low reading if you have a mechanical op gauge, or if its an electric op gauge, it's sender, or electrical connection may be faulty.

To test the IAC, disconnect it's electrical connector, its working if engine idle speed changes, or runs rough, or stalls, if no change, suspect the IAC.

With the vintage of this ride, could also be a vacuum leak thats so bad the IAC can't compensate, so include a stuck open PCV valve, or leaking vacuum hoses to it, or other vacuum leak sources to your low idle speed suspect list.

If fixing idle speed doesn't cure the oil pressure problem & if it came about suddenly after some event, like an oil & filter change, suspect the wrong oil filter was used, or it has an internal problem, or maybe the wrong/lower viscosity oil was put in & the oil pump can't make good pressure with the lower viscosity lube at idle speed.

More clues would be helpful in making better guesses, so if you have a CEL lit, most autoparts stores will scan the computer for trouble codes at no charge, then post All code Numbers found, as they can offer up good trouble shooting clues.

Some thoughts for consideration, let us know what you find.

 

Hey thank you for the responce and I took it in today and they found out that the drop in the rpm after you give it gas in neutral was due to weatherchecked vaccume lines that where cracked but they did not have a computer scanner that had the same plug in they only had one for a 96 and newer and so was wondering if it does end up being the pump "but hopefully just a sensor" how much would it cost to replace the oil pump?

 

No idea what a pan drop & pump replacenment would cost, if you don't get a reply here maybe try the F150 forum, bet someone there would have an idea.

Is the engine idle speed ok now & if so, is the op still low????

If it's still low, did this problem come about suddenly after some event, or slowly over time????

 

I have not fixed the lines yet but the pump pressure problem came slowely over time and it just recently jumped to almost on the very low side.

 

You could remove the OP sender, install a mechanical shop gauge to check the oil pressure.
Is the engine sludged up inside, or have heavy pan deposits????

 

The stock oil pressure sensor for a '94 is a pressure switch, not a real pressure sensor. It is designed, opposite of an "idiot light" switch, to put the gauge needle in the middle if there is 5-10psi or more, and zero if less. If the gauge reads low, but not zero, clean all of the electrical connections between the sensor and gauge.

I would still connect a mechanical one temporarily and see what the real cold and hot oil pressure is. Do not just replace the oil pump, which is not a trivial task with the TIB or TTB suspension under the oil pan. Also, it may be a bearing problem or other internal oil leak if the engine indeed has low oil pressure. 10psi per 1000rpm hot oil pressure is ok.