fuel economy dropped off drastically

[pontiacfieroguy]

the fuel economy in my 88 2wd 5spd 2.9v6 just dropped off drastically tank before last i went 330miles and the last i only got 210miles. ive checked for vaccum leaks and didnt find any and even had a mechanic buddy have a look at it and he didnt find any. it has a new fuel pump and filter. anybody got any ideas as to why this happened? ive havent driven it any harder than usual and its got me baffled

 

[holyford86]

extended idling? fuel leaks? codes? Switch to a different gas station that sells E10?

 

[2ndgen]

been having the same problem with mine and been doing some reserch and found that it could be caused by the coolent temp sensor i just replaced mine and took it for a test drive it ran better then befor smoothed out the rough idle, but now my truck wont start i think my ignition switch went out but the coolent temp sensor is only like 20 bucks..

 

[TwoWhels]

Put the Explorer radiator in mine...cooled the engine down to where it should have been...picked up 3 mpg
About 21.5 now

 

[pontiacfieroguy]

extended idling? fuel leaks? codes? Switch to a different gas station that sells E10?

no extended idling. i havent been able to find any and ive searched all connections. it isnt throwing any codes and im using e10

 

[bimmer325es]

dunno if they have o2's or not but check that, and i had a thermostat go bad stuck open so the engine never reached operating temperature, told the ecu its still in warm up mode that makes it run extreamly rich, was not on a ford though

 

[pontiacfieroguy]

dunno if they have o2's or not but check that, and i had a thermostat go bad stuck open so the engine never reached operating temperature, told the ecu its still in warm up mode that makes it run extreamly rich, was not on a ford though

it does have an o2 but i havent checked that because i figured it would throw a code. the stat is new but i beleive it may have stuck open a couple times because the truck ran extremely cool a couple times and it usually runs hot. i will replace the o2 later today and see what happens

 

[robertc1024]

Post back up with the results fiero. I had a bad engine coolant temp sensor, replaced that and the thermostat. My truck seems to run great, but my mileage is going down down down. I suspected the O2 sensor, but I'm not getting any codes either. I'm also imagining twisting that puppy off with the threads still inside the manifold - or wherever it is. Haven't looked.

 

[bimmer325es]

obd1 systems are "usually" right before the cat, and obd 2 systems have one before and after.

 

[greenpus]

sometimes a sudden drop in fuel milage is a mechanical issue such as a brake sticking. Been there, done that. Had a front sliding pin stick which caused drag on my front disc brake. Milage dropped from 26 mph to 15

 

[robertc1024]

Been there, done that too. Both of my front calipers stuck on a 70 mile trip. Truck overheated, would hardly move. If I spat on the front wheels, it sizzled. Apparently this is really common on Rangers.