Fuel problems!!!! [Archive] - GrandAmGT.com Forum


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02-28-2013, 02:08 PM
Hey guys. ive got a 2004 grand am Se with an unfortune problem...

A week and a half ago i got my fuel pump replaced and since then i have been getting terrible mileage. about half a tank gone and im only 150kms in. when i set at 1/4 tank left i am only at 200kms on the tank. I just got the fuel pump replaced again due to possibly being defective. I have changed the fuel filter 25xxx ago and just ran Seafoam through the tank. Ususally i get about 350-400kms when driving city, but im getting about 250-300kms. Its not leaking fuel nor does is the car running rich. I have no Engine lights coming on. Just want to know why im getting terrible mileage.? My car went from 1/2 full to 1/4 full in 50kms of driving.... :'(

03-02-2013, 10:23 PM
old pump was weak and not supplying the car properly?

just a thought... not 100%, barely 75% sure

03-03-2013, 08:34 PM
Nope, i was getting better mileage when i had the old fuel pump in. I got the pump replaced under warranty. Strangly enough after i got it replaced i went to the gas station to fill up cus the light came on, and its usually 43 litres, well i filled up all the way and it was only at 36 litres. Cant seem to figure out why im getting bad mileage.

03-03-2013, 08:46 PM
When was the last time you checked your mileage before the pump change?

03-03-2013, 08:48 PM
There's been a lot of talk of this lately..

As a pump ages, it becomes less efficient, and instead of pumping at 100%, it may be running at say, 90% capacity. So, every liter you think you're using, the car actually only used .9

Now that you have a new pump, 1 liter is 1 liter, due to the new pump doing what it's supposed to do. That pump isn't like an on/off switch, there is a useable range, and the car will compensate for a slight lessening of fuel, but it can only do so much, and once the pump gets below whatever the lowest point of the range is, the car shuts down.

That is the theory I'm operating on here, I don't mean that I'm some engineer and I know it's the gospel, but that is the only thing I can come up with, and nobody else seems to have a better theory lol

as far as not putting as much in, unless the new pump is like 5 times the physical size of the other one, causing a displacement issue, I have no clue why you wouldn't be able to hold as much petrol.

**Note how I Canada-converted my convo??? Yea, Yea I did :D **

Sorry I'm not more help, but I don't want to see you stranded with no response man.

03-03-2013, 08:48 PM
I was getting about 350Kms to a tank (Winter), i reset my trip every time. But on the same tank (when my pump died) i noticed my mileage started to go down a bit. Since then it hasnt been the same

03-03-2013, 08:51 PM
Well the pump was actually the same size which was weird. I was gonna keep the other one but i decided to not take it. My mechanics are all stumped. Could it be a Fuel Pressure Regulator?

03-03-2013, 08:57 PM
If it's leaking, then yes you can get extra fuel in there and lose mileage, I'm not sure that you'd see THAT big of a change off the FPR tho.. but they're a 100K mile part, they should be changed at that point, if not before.

03-03-2013, 09:02 PM
Well if there is a problem with the FPR then my car wouldnt run properly or even get fuel to the car to start it. It drives great. I just dont understand what it is. There is no leaks or codes. MY cold air intake is 30xxx and my spark plugs and fuel filter are at 25xxx. ITs not burning rich either. I also tried using Seafoam too.

03-03-2013, 09:06 PM
No, the FPR can leak, and then extra gas seeps in. Mine had the issue when it was warmed up, I had to hit the gas pedal to get it to start, as it flooded out a bit after I shut it down.
I honestly do not believe that FPR would cause that dramatic of a change in fuel mileage... and you're probably the 7th person I can think of this winter with a similar complaint. There has to be some sort of answer, but we're not sure.. they may have changed something in the pumps themselves, I don't have any idea why they would, and here again, I doubt it. I wish I knew what it was man, I'd feel like I needed to wear a cape while I was on here lol

03-03-2013, 09:16 PM
I agree with coop, my FPR went and I just experienced trouble starting, nothing else.

03-04-2013, 05:33 AM
The only thing is though, my car is starting all the time with no hesitation and no back firing at all. I moved my car in the morning and there was no leaks from where I was parked

03-04-2013, 07:58 AM
Pull the vacuum line off the top of the fuel pressure regulator with the car running. If your regulator is leaking you will have fuel in the line.

03-04-2013, 05:03 PM
Nothing is leaking. Gas is still in the tank. just fuel gauge is telling me i have less when there is really more in the tank?