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My wife has a 2002 chevy cavalier and the fuel pump went bad in it about a month ago(did fuel filter at the same time). I replaced it and it and now we are getting about 170 miles on a full tank of gas and before we were getting about 300. the average mpg we are at now is about 12. I have checked for leaks and have noticed nothing on the ground after driving and I can’t see any evidence of leaking when looking under the car. Just did an oil change and replaced the air filter and it is still getting bad mpg.
the spark plugs are not that old and don’t look too bad. although when the fuel pump first went out and the first thing I went to do is check for spark, well it seems as though the first spark plug I tried somehow got cross threaded and I cannot get it out now but I was able to put it back down with no problem so I’m not sure if this is something that could effect it or if that’s just another problem on its own. And the only other thing that was messed with when it broke down was the intake to the throttle body was taken off as we were trying to find where to test the fuel pressure so maybe I put something back together wrong and I’m getting a vacuum leak?
overall the car seems to run as it always has but its just taking a lot more fuel, doesn’t misfire as we had that problem with it awhile back and it was a spark plug.
thank you for any help I appreciate it very much.
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unfortunately I don’t have access to one of those and they are pretty spendy. But I checked for a vacuum leak and couldn’t find any and also just noticed that one of the other plugs was loose, when i pulled the wire it was wobbling. Although I don’t think I touched that one when it broke down and we checked out mpg right before the fuel pump went out so it was a significant drop right after this.
If it has an in tank fuel pump it could be that there is an o ring in the fuel pump compartment opening and if it is missing or leaking the fuel could be evaporating through. An indication of this would be a smell of gas in the cabin or around the compartment for the fuel pump opening.
Given that it happened after you replaced the fuel pump you might want to check your installation. If the sending unit isn’t working correctly you won’t get accurate fuel level readings. What I mean by this is that your tank may not be empty when you do your mileage calculations.
Thanks for the responses. I don’t think that the fuel reading is off as it is still costing almost 40 bucks to fill it when it’s down to e. that’s about what it was costing before to fill it. Tomorrow ill check the fuel pressure and most likely remove the gas tank again as check everything( tank has to be removed to access it it doesn’t have a way to it from under the seat)
One other question is that the fuel filter is very close to both the supply and return line. What would happen if I put the wrong one onto the filter. Would it run at all even. I think I put that on correctly though.
And I did feel like I could smell gas when I got under it last to check for leaks and I had just been running it. Couldn’t see anything though.
I don’t think the car would run if you fed through the return
line.the injectors would never see fuel.sorry to read about ur problem, gas isn’t cheap. your best bet is drop a deposit at autozone and they will loan you a scanner free, if your smellin gas could be a supplie line losened up when you reinstalled tank, you also could have bent the gauge reader in tank and your not burnin tank down to empty, i believer the fuel regulator on your model has a bleed off when pressure is high, i’d get that scanner, free and they are god for finding problems,good luck
well it looks like the problem is that it’s not reading the gas level correctly. dropped the tank and double checked my work. their was roughly 7 gallons of gas in the tank that holds 14.1 but it was reading at quarter tank. put everything back and still reading quarter tank when it really is at half. looks like my wife was not fully paying attention to how much it was costing when she topped off the tank. Ill probably run it till it actually dies and carry a gas can with me, top it off and see how much it actually takes to fill it and then run it till it dies again and see how many miles we get out of that. I know you shouldn’t run it on e as it needs the fuel to lubricate right but should it be ok as long as we put gas back into it right away?
thanks again everyone for the help and sorry it ended up being something stupid lol. I’ll see about being able to get a replacement from the parts store as well if its not too late. looks like i bought it in September.
Your sending unit has a problem.can you get just the sender?
unless its under warranty.just make sure the wiring is connected.
if you do fill the tank.what does it read?when topped off it reads as full and just seems to drop to e pretty fast making it seem as though it is burning through gas pretty fast. I double checked all the wires that i had to splice into it for the sending unit as it came with a new wire harness for that. the wires are connected correctly and tight. I also checked the movement and connection of the float when i just had it out and it seemed fine.
When putting the fuel sending unit in the tank,was there any rubber bumpers on the bottom of the sending unit that may sit in a location in the tank to center the unit?
Had something similar on a ford truck,tank half full and interior dash fuel level was on empty.
Also does this vehicle have a fuel pressure regulator in the sending unit or under the hood on the fuel rail?it might be leaking.See if you can locate the fuel smell….if in front or rear of vehicle…if at start up or after driving awhile.
If the sender arm was bent during replacement it could account for the discrepancy. Something you mentioned about smelling gas also stuck out. You should not smell gas as it should be a sealed system. In fact the evap system is designed to handle and detect this very thing. If you have a leak somewhere then it’s possible that some of your fuel is evaporating.
I’m still on board with the level not being read correctly however as you may be onto something there. Keep us posted.
DC,
If your wife is anything like mine (doesn’t refill until the idiot light comes on), that extra safety margin might be a blessing in disguise!
It is funny that you mention this. I replaced the fuel pump and sending unit (same part) in my Tahoe a few months ago. At first the level seemed to be corresponding with the true level, but lately it seems like it is reading lower than the actual reading. Oh well, better to have an off reading in this direction versus the other I suppose.
Jason
I don’t think I’m leaking any gas, i may have just had the smell on my hands from touching things in the garage or it was just because i still had some shop towels in the garage that had gas on them from when i had changed the pump. When I thought i had smelled it it wasn’t very strong. When I took the pump out again I double checked everything as I took it off to see if anything was loose, checked the o ring and everything seemed fine and I did the same when putting it all back together. The only thing that seemed a little weird was the line going into the fuel filter took no effort at all to come off but i checked that area to see if it was leaking with the car running and it didn’t do anything so I’m just guessing that’s how that connector works. But I’m assuming that the level is just not reading right with the fact that i pulled half a tanks worth out when it was reading a quarter tank. The receipt for the part said a 60 day return policy and its been just a little over 90. That’s what I get for buying from the cheapest place in town when I’ve already had bad luck from them lol. From here I think the best thing to do is just correctly check the mpg and if its still off it might have a leak somewhere. I really appreciate all the help guys.
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