230miles, from Seafoam?

[prevarications]

My fuel economy seems to be dropping since last summer when I seafoamed the car. I've been able to go 330miles to the tank with Mobil 89 prior to that point, but the last fillup took 13 gallons and had gone 230 miles.

I dont have a lot of miles on it...35k. It has a Magnaflow exhaust, E3 plugs, MSD 8.5mm wires, new fuel filter, FTRA, and almost all fluids are full synthetic and recently changed. My tires are new, and pressure has been checked at 32psi. My driving patterns, commute distances have stayed the same. I dont rev past 3k, and normally take the highway at 65mph. I fill up at the same gas station, and the same pump if I can. I do note that I tend to go further with Mobil gas vs Sunoco.

I also notice a whine at idle stemming from the rear of the car that goes away upon throttle; I'm told it may be the fuel pump.

Could seafoam be the culprit? The plugs/wires were replaced since then. Is there anything else that can explain the poor mileage, like that fuel pump whine?

Thanks, Rick

[97rs4life]

Re: 230miles, from Seafoam?

did you change your oil after you seafoamed the car?

[flamingchicken]

Re: 230miles, from Seafoam?

he said he sea foamed it last summer, i would believe that an oil change has been done...and if not, DO IT

[venom3300]

Re: 230miles, from Seafoam?

i filled up at 246 miles today with 13 gallons... and thats with more than normal highways miles...

as for what happened... idk

[bigbrian442]

Re: 230miles, from Seafoam?

Gasoline blends change several time a year and the winter blends tend to give you less MPG then the warmer weather blends.

[hockeyman]

Re: 230miles, from Seafoam?

Gasoline blends change several time a year and the winter blends tend to give you less MPG then the warmer weather blends.

Agreed. Ethanol burns-up faster, and since there's more Ethanol added to gasoline fuel during the winter...do the math.

I just did some calculations on my GTO two nights ago, and I'm getting 17.2 miles per gallon in the winter. During summer, I was getting around 20.5 mpg's.

[Mighty Thor]

Re: 230miles, from Seafoam?

Gasoline blends change several time a year and the winter blends tend to give you less MPG then the warmer weather blends.

I concur.

[nascar24jd]

Re: 230miles, from Seafoam?

Gasoline blends change several time a year and the winter blends tend to give you less MPG then the warmer weather blends.

Agreed.

I decided to stop looking at my MPG. I enjoy my car and drive it everyday. It gets crappy fuel economy and I do not care...

[prevarications]

Re: 230miles, from Seafoam?

Yes, the oil's changed regularly with Mobil 0w30 full synthetic, the new one with the green label.

I guess the lower mpg is good to get used to as I was contemplating an SUV/pickup as a winter beater.

[Rob Bell]

Re: 230miles, from Seafoam?

230 miles/13 gals is 17.69 mpg which is bad. Mine gets 23-24 around town and 26-28 hwy. I think most 3.8's on here get in the low-mid 20's. I would suggest checking your O2 sensors. They can get "lazy" and make the mileage go down. They don't have to be bad enough to set a code. They have to be checked with HPTuners or a scan tool to see if they are switching fast enough.

Also, unless you have a good reason to, you should be using 87 octane. Higher octane = lower mileage unless you have mods and a tune to warrant its use.

[lil' jon]

Re: 230miles, from Seafoam?

Is it possible for seafoam to damage the fuel pressure regulator? I'd think if it can handle gasoline passing through it then seafoam wouldn't be an issue, but who knows.

[bigbrian442]

Re: 230miles, from Seafoam?

Sea foam is Naphtha and pale oil. Naphtha is pretty nasty.

[lil' jon]

Re: 230miles, from Seafoam?

Hmm maybe the seafoam ate through the rubber membrane in the FPR. Aside from the poor gas mileage, how's the car run?

[Mighty Thor]

Re: 230miles, from Seafoam?

I never heard anyone complain about seafoam.

I put this stuff and in my Fiero with had 160k and it got rid of a lot of junk in there and I was able to pass smog with flying colors.

[prevarications]

Re: 230miles, from Seafoam?

Hmm maybe the seafoam ate through the rubber membrane in the FPR. Aside from the poor gas mileage, how's the car run?

The car runs fine otherwise...i used seafoam to cure a hard crank/start, if the car sits for more than 3 days without being driven.

I saw the grey smoke, and now I can leave it untouched for 3-4 days without it having it wheeze upon cranking.

Any brand suggestions for a replacement FPR? Should that be done in tandem with the fuel pump replacement? Walbro 255 seems to be a popular choice, but theres more than one in the Summit catalog, and its hard to tell which one I'd need.