Have a 1999 F350 with the 5.4 Triton. While driving lost oil pressure. Then it was fluxuating. Now it acts like it's locked up. Any suggestions?

If oil is full, replace oil pressure snsr/sender and recheck. You didn't post what kind of vehicle you have , many use the oil pressure signal to keep the fuel pump running

ur oil sending sensor is bad it reeds the oil pressure

This fix works for 2.7L engine. Worth having your mechanic look at.

Answer
NO: 08-36-99
SUBJECT: Engine Oil Pressure Light Flicker
DATE: Oct. 15, 1999
OVERVIEW:
This bulletin involves adding a terminal/wire/vent to the oil pressure switch connector.

NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A 2.7L ENGINE.

SYMPTOM/CONDITION:
With a hot engine the oil pressure light may be on or flicker on at idle.

DIAGNOSIS:
Verify engine oil pressure as described on page 9-21 of the 1999 Concorde/Intrepid/LHS/300M service manual (Publication No. 81-270-9140). If engine oil pressure is within specification perform the Repair Procedure.

PARTS REQUIRED:
Qty Part No. Description
1 05017800AA Wire Terminal/Vent


REPAIR PROCEDURE:
Raise vehicle on a suitable hoist.
Remove engine oil pressure switch connector from switch.
Remove sealing dart from the empty cavity at the rear of the connector.
Pull terminal locking ring outward from front (switch) side of connector to gain access to terminal locking tabs.
Install wire terminal/vent, p/n 05017800AA, in place of the removed sealing dart. Slide locking ring back into place.
Attach the connector back on the oil pressure switch.
Spot tape the wire/vent to follow the harness towards the top of the engine compartment.

remove the sump and check the pick up pipe ,it has a gauze filter and this is blocked with clag from the engine which is caused by not having the oil changed regular .quicker to do this than trying to flush the engine

I suspect you have had an oil pump failure. To get at the rotory gear oil pump you will have to drop the oil pan. After you take the pan off, ( having drained the oil the oil pump is what the oil pick up line leads into. That pick up assy. is a round shaped disc with a screen inside it. Clean the screen first then the oil pump. Install new oil pan gasket on reassembly. Hope that helps you. Please let me know.

Hopefully the engine was not damaged when the pump broke. If it was you may need a complete engine rebuild, MAYBE.

Most likely it's the oil sending sensor, located beside the oil filter. You can change it, just be sure to have old newspaper or rags laying around the area where you will work, because a little oil will be lost. The part isn't expensive, for mine on a Ford Expedition was around $35 and took 5 minutes to change. Just un-plug the connector going to the sensor, and a larger wrench will be needed, large (7/8, 15/16) somewhere in that range of size.

Oil pressure sending unit shuts off fuel pump if there is a problem with the unit (Oil pressure sending unit maybe malfunctioning)

your oil pump does that on purpose - more noticeable with a dented oilpan as pressure is slightly increased. nothing to do until it goes (if it goes) unless you want to throw parts at your car anyways.

Just to add, hope this helps with sensor location. The spec I saw was 30--80 psi oil pressure at 3000 rpms. In the old days they used to say for generic spec, 10 psi for every 1000 rpms. Always use the proper spec. You might be able to use analog pressure gage to screw in to replace sending unit to double check oil pressure. Just my opinion.

The oil pump is in the pan at the bottom of the distributor.