i got a 1990 ford ranger single cab 2wd automatic 2.3 and its only getting 11 mpg it had a blown head on it when i bought it so i bought a new head for it all new spark plugs (btw it has the 8 plug setup) new wires and it seemed to run fine then i found an exhaust leak so i fixed that and i replaced the sending unit cuz the old 1 had a hole in the float (thought that would fix the gas gauge but didnt) so i bought a fuel gauge and the gauge reads backwards even after double checking the ohms and stuff but it works good enough for me just have 2 remember E if full and F is empty but anyway after about a week of running it i noticed it was guzzling the gas and i found that 2 of the plug wires were on the manifold melted in half so i replaced the wires again and while i had the time i replaced the fuel pressure regulator and im still only getting 11 mpg any ideas?

 

Does the truck run at normal operating temp? Sometimes if the thermostat is stuck open, the truck wont warm up to the proper temp and doesn't go into closed loop. This will make the truck run rich. Also you could have O2 sensors that are not functioning properly. Just a few things that could be wrong.

 

no actually it runs at about 160, however it has a brand new thermostat in it..when i replaced the head i replaced the oil pres sensor and thermostat and plugs....i just thought that maybe the location of the sensor was why it ran at 160 its located on the bottom side of the intake manifold ( a ***** to get to)..when i had the bought the truck the temp or the gas gauge in the instrument cluster didnt work so i had just bought gauges instead of a whole new cluster and went from an electrical temp sensor to a manual one... when i unplugged the electrical temp sensor it threw the check engine light on so i plugged the sensor back up and just left it hanging there and continue to use the manual gauge you think it could still be using elec temp sensor since that is what it is from factory and the fact that it is never actually heating up to the engine operating temp that that could be the issue?

 

Yes, the temp sens should be plugged in at least for the computer. It lets it know when to shorten the injector pulse after the truck is at operating temp.

 

160 is a low operating temperature. That could be part of your problem. If the PCM doesn't see the engine getting up to temp the O2 sensors won't work properly and the computer may stay in closed loop mode, which is not ideal for mileage.

 

I think you got that a little backwards. It's supposed to be in closed loop when it warms up.

 

Yea I can never keep it straight in my head.