93 300 6, oil gauge goes squirly

[Krafty]

today I just picked up a 93 f150 4.9L auto 4x4, runs great, drives great, all kinds of power, tones of new parts.

my problem is after driving for a little while and the engine warms up the gauge drops to below the low red line when coasting or at idle, way off the gauge. always jumps back up with a slight touch of the gas.

included in the new parts were oil pump, pan and gasket, no visible leaks. Oil in it looks clean and good, ( no coolant contamination)

the only thing that has me bothered is sometimes when it does it I swear I can smell oil coming from my dash vents.

any ideas.

 

[miesk5]

yo K!

Nice truck and engine combo!

Go thru this info to test, as long as you have da single fuel tank;

Testing & Connector Pin-Outs in 92-96 Bronco; Sender Range: Full = 160 Ohms; Empty = 16 Ohms; "... gauge that pegs past full indicates an open circuit (broken wire; unplugged connector; corroded terminal; burned sender) on the Y/W wire. gauge that pegs past empty indicates a short to ground (pinched to the frame, body, or dash supports) on the Y/W wire, OR a sunk float. gauge anywhere in between that doesn't move indicates an open circuit (blown fuse; corroded terminal) on the power (battery) side of the gauge OR a bad instrument cluster ground at C251 pin 9. The terminals of C251 (& C250) are known to corrode & lose contact. Polish both the connector pins AND the film circuit pads with brown paper or a pink eraser. The larger version of C441(WPT454) was used until 93. The level sender can usually be disassembled & repaired by bending the wiper arm inside the plastic housing to apply slightly more force..."

Source: by Steve83 (Steve, That dirty old truck) at http://www.supermotors.net/registry/media/744437

Testing in 87-96; Fuel Gauge Moves from E to below E; "...Disconnect the connector at the fuel tank, ground the yellow with white tracer wire (make sure you have a good ground),turn the key on-if the gauge goes to empty, chances are, the fuel sender is the problem. If the gauge doesn't move, then recheck the grounding of the Y/W wire,if it is good then the problem is is forward of the sender (wiring/connectors/instrument cluster)..."

Source: by 85bigbronco

This is a my 96's EVTM;

PINPOINT TEST A: FUEL LEVEL READS INACCURATELY

A1 VERIFY POWER AT LOAD SIDE OF FUSE PANEL

Key to RUN.

Using Rotunda 88 Digital Multimeter 105-00053 or equivalent, verify system voltage at the load side of fuse. verify system voltage at the feed side of the fuse.

This is Ford's way of sayin' .. check Fuse..lol

Now, I'll skip the instr cluster part and suggest you look at the tank connector for all other tests they describe;

http://www.thedieselstop.com/faq/9497faq/maint/stj/stjd1017.htm#pptd1001

So in Tank Connector C441;

Y/Wh is gauge power

Bk is gauge Ground

Go to

A10 CHECK FUEL TANK SENDING UNIT GROUND

Key off.

Measure the resistance of the BK wire at the fuel level sensor connector to ground at battery.

Is the resistance less than 1 ohm?

NO - SERVICE the BK wire from the fuel level sensor to ground.

Yes - Inspect fuel tank for distortion or damage.

Is the fuel tank damaged?

Next tests are on da float

Summary is;

"...With the sending unit float arm in the empty stop position, resistance should be 15 ohms (below E). With the sending unit float arm in the full stop position, resistance should be 160 ohms (above F). The fuel gauge should read empty at 22.5 ohms and full at 145 ohms..."

Since the prev owner has that oil pan /gasketc etc. I'm guessing a big 99.9% that the oil aroma is due to a badly rusted pan (Ford used the badly rusted outer roll of sheet steel for "non-appearance locations; meaning non-body panel, hood, etc components) and/or bad gasket.. noisy pump.. et al

I'd clean the new pan and get a great coat of POR15, Rustoleum red primer or Rust bullet on it; some even prime the inside of da pan.

GL!

 

[Krafty]

hey miesk thanks for the reply.

for clarification

it is strictly my oil gauge that is acting up not the fuel gauge. ( I understand that some of the symptoms and test you listed are similar)

I also have Dual fuel tanks and they both work wonderfully.

and by "touch of the gas" I mean throttle.

my main issue is I'm not used to dealing with the efi systems, does the 93 have an oil idiot light as well as the gauge? if so I have not seen it and would imagine it would work off the signal going to the computer and not the signal going to the gauge as a redundancy issue. but then again that's just my way of thinking.

from what I can gather from your post my likely culprit is a short in the circuit to the gauge? as opposed to low oil pressure where the gauge would likely stop at or closer to the L of the low side?

if L is > or = to 0 then its drops to negative numbers by a lot .

 

[miesk5]

yo K,

Sorry 'bout that; I didn't read your info correctly; I was still on a fuel gauge problem for a pal who had e mailed me and I just failed to read your complete title.

I think you should check it out for actual low oil press problems asap. We need to rule-out a faulty oil pump, screen, bearing wear, etc.

The Oil Pressure sender is merely an off-on switch for these years; I think Ford went from a true analog (actual psi) sender/gauge combo in 86 to this on-off set-up.

-------



Here is the 4.9 diagram w oil pressure sender (#35) Location by Ford via Steve83

You can convert it to an actual psi gauge.

======

I don't have nor have I seen the idiot light on 92-96 Broncos or Ford F series.

Here is the instrument cluster overview by Ford via Steve83

This is by Ford:

The oil pressure gauge is a magnetic gauge movement consisting of three primary coils, one of which is wound at a 90-degree angle to the other two. The oil pressure system uses a switch and a fixed resistor; the resistor is attached to the engine wiring harness. A primary magnet, to which a shaft and pointer are attached, rotates to align this primary field, resulting in pointer position. The bobbin/coil assembly is pressed into a metal housing which has two holes for dial mounting. There are no adjustment calibrations or maintenance required for this gauge.

Oil Pressure Sender

The oil pressure sender controls the magnetic oil pressure gauge's pointer position. The oil pressure sender (switch) closes under normal engine operating conditions. The oil pressure sender opens with the engine off and no oil pressure.

Sender Failure; "Corrosion or faulty electrical connections; If the oil pressure gauge is pegged low after the engine is running, or is pegged high after the engine is running, or if there is intermittent illumination of an oil pressure indicator light, the sender could be faulty. Related Components to Check; All appropriate electrical connections to and from the sender The oil pressure gauge or indicator light; Appropriate fuses (see Shop or Owner’s Manual for fuse layout)..." miesk5 Note; enter applicable info for year, etc.

Source: by MOTORCRAFT®

Test & Installation Tips; "...My oil pressure gauge was reading on the "N" of the NORMAL range. After doing some research it seemed like it could be the oil pressure switch, also known as a sensor or sending unit. Disconnect the wire from the switch, ground it to the truck and turn the key on. If your gauge quickly moves to the left, the problem is most likely the switch. .............I advise that you go to NAPA and get an Oil Pressure Switch socket to do the job. The cost is about $7-$8, this will save you time and will help you reinstall the new switch. Wrap some teflon tape around the threads and install. Make sure that it is in tight, I don't know about torque specs, I just put mine in quite snug. Hook the wire back on and start your engine. For me it was the cure. My oil pressure now reads over near the "M" on NORMAL..."

Source: by Canoeboy146

 

[Krafty]

I was talking with the previous owners today. I was told its done that since they bought it off the original owner a few years ago, which is why they put in the oil pump and pan and gasket. after that their mechanic, who also happens to build and race ford cars and trucks ran some tests and assured them it was not loosing pressure. so im gonna look into the gauge and sending unit a little more closely. if the fitting threads are the same I have a mechanical gauge on my 89 302 i might try just to see for myself, after that if it passes I have 2 89 electric psi acorn sending units at my parents ranch which is where the 89 is going to spend its final days next weekend. if the oil gauge issue pans out then the only thing wrong with this truck is rust on the front fenders and rear wheel wells.

and for those fixes is either 2 patches and front fenders or get fender flares. so many options

 

[miesk5]

yo K,

Ok, that's good then.

I don't have the info on the sender fittings but they may be same as a 5,0/5.8 which is 1/4" NPT male or female; I have a few links on it in my site @ http://www.broncolinks.com/index.php?index=949

I have some flare Links using other than Bushwacker line up http://www.broncolinks.com/index.php?index=451

Such as;

Flare Info & pics (from a semi & modded) in a 91 Centurion

Source: by David B (dblue, One Ton 91, Centurion) at SuperMotors.net

Flare Info & pics in an 81; "...I wanted to install fender flares in my truck but they are not available in my country (Argentina).....so I got a set of cheap Warn flares in bad shape and sent them to make a copy.....Today I got the first set and installed them....the cost for each set it will be about $100.- bucks!!..."

Source: by Henri at uc4x4.com

Icelandic Source; "...they come from www.samtak.is..."

Source: by Oscar H (ICEBRONCO (Grinch)) at FSB

Modification; "...Heres what jeep flares look like, i went to the junkyard and they let me have 8 for 30$ and i only used 2 on the back, just marked it for the flare contour, got out the old air nibbler and i like the way it turned out....but my main reason was to cut off the rusted thru parts of the quarter..."

Source: by sparkysmotorsports at karting.4cycle.com

Modification; "...i used flares off of a 98 ford explorer sport 2 door 4 door wont work. the fender radius is almost the same. only mods i had to do was where the "V" shape is towards bottom of truck i had to slightly mod the flares by cutting them with a die grinder. the ***** holes along the fender lip also matched up nicely. it tooka couple of days of trial fitting but they look nice. and along the top i instaled small bolts so they look the pocket flares made by bushwacker. this was necessary to hold them tightly to the body. it cost me a total of 50.00 to put these on. flares where 30.00 at pull a part auto wrecking..."

Source: by shad351

hot links are in the site.

GL!