oil pressure guage crazy readings

[danger_ranger88]

1988 ford ranger 2wd 2.0l carb. how do you test the guage to see if its bad cause mine gives me different readings while driving... ill start the truck and the needle will go to about three quarters the way up before the H line, after awhile it will drop down to a qurter, a hour/min/sec it drops to the L mark or below even.... but i can shut the truck off for few seconds and it will be in the middle for 10 15 min then back to the H mark blah blah then to the L point... i bought the truck a month ago its done it the whole time, no oil leaks burns a lil oil i add a qt a week or two i think the guage is f**ked cause im for sure driving 30 straight days with something wrong having to do with oil pressure would of caused major damage within the first day/week... any suggestions please let me know id app. it!!!!!!!! thanks, Bryan

 

[danger_ranger88]

oh and forgot engine is not knocking nor is their any noisy/chattering lifters

 

[scotts90ranger]

the gage is a fancy looking idiot light, with anything over like 5psi it is supposed to show normal, anything less and it shows 0, if it's acting like you say there's a wiring issue somewhere, I put a manual gage on my truck for good measure.

 

[RangerFabWorks]

sounds like the sending unit to the gauge is bad. its behind the carburator on the left side of the engine in the back. replace that and see what happens, but i would do a manual gauge to be safe.

 

[Ranger4657]

this week some time i will be installing a aftermrkt oil gauge im wondering if theres a way to at least make the origional gauge look like its got pressure so when its running i wont have to look at a gauge that reads null. maybe just lead a +12v power from the ign. switch?

 

[scotts90ranger]

there is a way to make the stock gage read like a real gage, I just don't remember the stuff needed to do, it involves installing a late 70's sensor and bypassing a resistor in the back of the instrument cluster...

 

[Ranger4657]

yeah ive read that article it sounded iffy.. but possible... this is it
http://rogueperformance.com/oilsw.html

 

[SMTGREG]

When the engine oil pressure is normal, the oil pressure switch is closed (short circuit), allowing current flow through the 20-ohm resistor on the instrument cluster printed circuit into the gauge which drives the pointer to a position slightly above midscale. The oil pressure switch opens (open circuit) when oil pressure drops to a critically low level (4.5-7.5 psi), causing movement of the pointer to or below the "L" band. Ground the white /red wire going to the sender and guage sould go to about midway.

 

[scotts90ranger]

yeah ive read that article it sounded iffy.. but possible... this is it
http://rogueperformance.com/oilsw.html

it's not iffy, it's completely legit...

 

[Ranger4657]

=]

 

[scotts90ranger]

=]

thanks for the link by the way, been a while since I've looked it up and have been thinking about it lately...

 

[Ranger4657]

yEawH! No problem =]