Sudden fuel mileage drop:
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Senior User
Joined: Apr 2003
Posts: 280
Likes: 0
From: Iowa
Sudden fuel mileage drop:
I've had this problem for a month now:
I use to get 12-17 mpg in my 94 with 302 engine.
Recently mileage has dropped to under 10 mpg (like 8mpg)
It's winter, so the fuel is crappier, BUT what else could be at play.
The only code my OBD is tossing at me is 121, which is that the voltage to the TPS is over/under what it should be.
The truck idles shaky once it warms up too (like at a stop light). Runs smooth when first started, until warm-up.
What are some things you guys would check, if this was happening to you. The spark plugs are about a year old, rest of the ignition is stock from when I bought it. I've never messed with timing. Seems like a fuel injection issue to me if I'm losing this much fuel, but not getting any extra ooomph out of it.
I used a quarter tank driving 40 miles this weekend. Something is seriously wrong. The truck feels like it has much less power too, or like dead spots throughout the RPM range (or possibly dead spots on the throttle %)
What sucks is that I have less get up and go AND my mileage is super crappy.
Give me a checklist of things to get after that could cause this fuel dumping + no power.
THanks,
Luke
I use to get 12-17 mpg in my 94 with 302 engine.
Recently mileage has dropped to under 10 mpg (like 8mpg)
It's winter, so the fuel is crappier, BUT what else could be at play.
The only code my OBD is tossing at me is 121, which is that the voltage to the TPS is over/under what it should be.
The truck idles shaky once it warms up too (like at a stop light). Runs smooth when first started, until warm-up.
What are some things you guys would check, if this was happening to you. The spark plugs are about a year old, rest of the ignition is stock from when I bought it. I've never messed with timing. Seems like a fuel injection issue to me if I'm losing this much fuel, but not getting any extra ooomph out of it.
I used a quarter tank driving 40 miles this weekend. Something is seriously wrong. The truck feels like it has much less power too, or like dead spots throughout the RPM range (or possibly dead spots on the throttle %)
What sucks is that I have less get up and go AND my mileage is super crappy.
Give me a checklist of things to get after that could cause this fuel dumping + no power.
THanks,
Luke
Senior User
Joined: May 2003
Posts: 203
Likes: 1
pull the battery for 1/2 an hour to reset the computer, check your o2 sensor is tight in the pipe (mine was loose and letting in o2 thus making the computer to richen up the mixture, I took the opportunity to change it for new)
Postmaster
Joined: Jun 2004
Posts: 2,665
Likes: 0
From: B/CS, Texas!!
-You can test or replace the TPS. (I would just replace it). That might be the problem to everything.
- Since everything is stock except plugs, replace cap, rotor, wires, filters, etc.
-Do a test with the engine running. At 8mpg, code 173 will show up. If it doesn't, the O2 sensor is dead. Replace it if it has over 60k miles.
-Check your fuel pressure.
- Since everything is stock except plugs, replace cap, rotor, wires, filters, etc.
-Do a test with the engine running. At 8mpg, code 173 will show up. If it doesn't, the O2 sensor is dead. Replace it if it has over 60k miles.
-Check your fuel pressure.
Posting Guru
Joined: Nov 2004
Posts: 1,467
Likes: 0
From: N. Gwinnett Co. Georgia
Check your fuel pressure regulator on the fuel rail and replace the TPS. You can pull the vacuum line and see if any gas is present in it. Go to a parts store and rent borrow a gauge to use on the schraeder valve on the fuel rail. Shoud read 38-45 psig.
