My 92 f150 with a 4.9 is not getting up to running temp also the check engine light comes on than goes out

 

check for codes. Maybe it's time for a new thermostat.

 

obd 1 is limited in reporting if coolant temp is not ok... i would check that thermostat is ok, there are no coolant leaks (pressure test), as well as water pump is still good as well.

 

I replaced thermostat and check the water pump and it's fine

 

Why do you think the coolant temperature has anything to do with error reporting?

 

The factory temperature gauge is well known to be inaccurate. Verify the real temperature with a mechanical gauge or point an infrared temperature gun at the thermostat housing.

Run the Key On Engine Off tests and stored code (CM) display to find out why the CEL is turning on.

 

It's got a manual temp gauge in it I'll try looking up the codes

 

What temperature is the gauge reading?

Where is the gauge attached to the engine?

When did this problem start?

 

pinkpantherusmincus, I read your reply to mean that OBD1 has a hard time reporting on whether or not the coolant temperature is within normal operating range. If that's what you meant, it's incorrect. OBD1 systems accept a direct input from a coolant temperature sensor just like OBD2 does, and would certainly not have any trouble using the reported value for diagnostics.

OP, yeah check codes but how long has it been since the t-stat was last replaced? If it ain't ever been changed then it wouldn't surprise me to pull the thermostat housing off and find the 'stat in pieces. They do wear out and break just like everything else mechanical.

If it were my truck the first thing I'd do is hit the thermostat housing with an IR temperature scanner.

 

Was Reading at 180 when warm. I have the manual sensor in replace of the stock electronic sensor on the side of the engine. a day of so after i put the manual temp sensor in

 

It would not be the first time a "new" thermostat was bad out of the box. Pull it out and test it with hot/boiling water and a thermometer.

 

Don't bother with the "fail-safe" thermostats either. Most people say they open once and stay that way. They're supposed to lock open if the engine overheats but apparently they tend to lock open even at normal temperatures, in which case you might as well have just not bought a thermostat in the first place.

 

It's get up to running temp now fault thermostat Thanks For The Help

 

Thanks for the feedback!