Burnsedn

When my 92 f150 4.9l efi warms up the temp gauge fluctuates and runs sluggish with a noticeable hissing/whistling sound from the air rake/ air diverter..I've replaced the egr valve, egr valve selenoid, map sensor, coolant sensor, oil level sensor, vacume lines, tab tad and vacume Selinoids, alternator, dist cap, spark plugs, spark plug wires, icv, idle control valve selenoid, pcv valve and hose and grommet, oil n filter, air filter, O2 sensor, pcm at one point, radiator cap, ect... Runs codes 33 and 44 on obd1....I'm sure I'm missing something. Right now when I drive it warms up then the temp gauge fluctuates and runs very poor especially up hill. I've tryed to replace the fuel filter but the line rusted on one end and can't get it off even though I know the filter is not that old. I can barely get the vacume line off the fpr which I don't know if that's bad. I've checked the fan clutch and it only goes about a fourth a turn with resistance. Any input would be greatly appreciated

Chris_1

iTrader: (1)

Did you replace the coolant sensor or the coolant sender. The sender just runs the gauge in the dash, has nothing to do with the computer.
So the temp gauge fluctuating is either the motor is actually heating up and cooling down like it shows, the sender unit is bad, or there's an electrical problem, probably a bad ground.
The whistling sounds like a broken vacuum line or possibly but not as likely a bad vacuum valve. Motor reaches operating temp and goes to open something (with a vacuum switch) and when the valve opens, there's your vacuum leak showing up.
The best way to get old hoses off is - don't just pull on them - twist it back and forth a little bit to loosen it,(use pliers if necessary) then pull it off. Same for your spark plug wires. The rubber sticks to the metal from getting hot, so you have to unstick it first.

Burnsedn

Yea, I checked the vacume lines and they seem fine. How do you check for a bad ground because I've suspected an electrical problem for quite some time now.. I'm sure I need a voltmeter. I found a complete wire harness on eBay for 80 bucks. Whoever had the truck before me spliced and cut the crap out of it.

Chris_1

iTrader: (1)

There's usually some grounding screws behind the kick panels inside to ground the electricals to the cab. There should be a clip on ground strap cab to frame on the passenger side. There should be a ground strap from the firewall to the engine. There are a few grounds from the wiring harness to the fenders and rad saddle.
And your main ground cable from the battery (originally) attaches to the frame and the engine.
Cleaning up all those grounds so they're good and shiny to make real good contact can help eliminate little (or big) electrical glitches. If you don't have a good connection to ground, it doesn't matter how good your power connections are.