Author Topic: Fuel Filter - dirty fuel question (Read 350 times)

Airscrew · « **on:** May 22, 2006, 12:00:22 PM »

A question:
I have a 1996 Buick Skylark, 3.1 v6, 38,500 miles. (bought it used a year ago with 10,900 miles)
2 months ago the car was running kinda sluggish so when I got the oil changed 2 months ago they also used a 3 part treatment to clean the tank, fuel injectors and the engine. They recommended changing the fuel filter but they didnt have one in stock at the time. Anyway after the first tank of gas i noticed an increase in gas mileage, from 22-24mpg to 25-27mpg. so now fast foward 2 months, gas mileage is starting to decline again, slipping down toward 24-25mpg (no change in driving habits, using the same couple of gas stations, newer stations so I'm pretty sure their holding tanks should be cleaner than most.)
I suspected that maybe I should get that fuel filter changed so i picked up a new filter and went last weekend and had the oil changed and had them replace the fuel filter too.
so now the question: The old fuel filter was filled with gas and what looked like water and it was black like old oil. Does anyone know what that could be? I know its possible to get water in the gas tank with condensation but that sure did seem like a lot of water. Also I'm wondering if the gas tank its self is shot or corroded? Were did all that black stuff come from? Considering the previous owner had the car since new (1996) and for almost nine years only put 10,000 miles on the car its possible it sat a long time with gas in the tank.

Should I consider removing and cleaning out the gas tank, replace it, or is there something I can put in the tank that will clean it up?

BGBMAW · « **Reply #1 on:** May 22, 2006, 01:02:13 PM »

so you put the new filter in..and it runs how?

I woudl say HELLL no ..its only a 1996??!!! Your gas tank has to be fine..replacing it seesm very very unusual

Run it..fuel filters are cheap..and usally a person with decent mechanical skills can replace one himself

Look on the internet for a forums about your style car..its pretty amazing the problems or things that will be psoted easy for you to read..and fix

Airscrew · « **Reply #2 on:** May 22, 2006, 01:11:16 PM »

Well the new filter was installed Saturday, and I'm on my first tank of gas with the new filter. Car runs fine, its seems to run better which i would expect. but if there is more crud in gas tank I'll be right back where I started from in a couple of months.

yea I could change the filter myself if I wanted too. I dont have a garage or a place to work so I usually have to drive 40 miles to my dad's house to do any work on the car. Its only 18miles to the nearest town and I have a place there were I get my oil changed. Guy that runs the shop said he would change the filter no charge.

I've read some of the forums but so far I've only run across this issue for diesel cars not gas engines.

Sparks · « **Reply #3 on:** May 22, 2006, 01:36:47 PM »

Airscrew - I would suspect your fuel supply myself. If they have had a tank rupture for any reason or a pipe crack they could be getting ground water into the storage tank. I would run the tank down, go to a different station for a few weeks, replace hte filter again, keep going to the new station and see what happens.

Airscrew · « **Reply #4 on:** May 22, 2006, 01:44:03 PM »

Sparks, I considered that, but the gas station I have used for the last 4-5 fillups just opened three weeks ago. Brand new from the ground up. Although its possible they may have gotten bad gas from a supplier.
Maybe I'll grab a sample my next trip and see what the gas looks like after setting a few days. I know our chief for the VFD told us not to buy gas from another station any more because they had too much crap in their tanks. He took sample and by the next day he saw all the crap that settled in the bottom of the bucket. He told the station owners and they shrugged their shoulders and didnt care.

Sparks · « **Reply #5 on:** May 22, 2006, 01:59:19 PM »

If it's a new station maybe they have a bad installation ?? leaking vent pipe, anything. Really sounds like groundwater to me - especially you saying it was black. We used to get condensation in the Jet fule tanks where I worked but it was always clear.

rpm · « **Reply #6 on:** May 22, 2006, 02:35:13 PM »

The black goo is mostly water. You likely bought some "transmix" at a cheap station. It's not that uncommon. A tanker driver gets a load of 1/2 water, 1/2 gas and it becomes mixed in transit (hence the name "transmix").

You can add a bottle of STP gas treatment with every tank for a month or so, or you can just use a pint of isopropol alcohol. Both will do the same thing, mix with the water and allow it to pass thru the filter and burn.

I would suggest changing the fuel filter again in a month or so just to get rid of any trash that was trapped inside. Oh, and don't use that station again.

Airscrew · « **Reply #7 on:** May 22, 2006, 02:58:40 PM »

you know now I'm going to check the gas. This is a new Texaco station, when they opened up they sold gas at $2.53 while everybody else in Austin was between $2.75 and 2.80. Price is now at $2.63. I'm also going to get a sample from the HEB and the BP in Bastrop where I also get gas. Those are the 3 gas stations I used the last year

rpm · « **Reply #8 on:** May 22, 2006, 03:46:19 PM »

There was a string of Chevron stations in Cali that got busted for selling transmix. Turns out there was a fuel truck showing up in the middle of the night pumping out gas and replacing it with transmix. The driver had a sweet deal going until he got busted doing it on TV.

Brenjen · « **Reply #9 on:** May 22, 2006, 03:58:24 PM »

The black is contamination, the contamination could be & probably is water, the recommendation for STP will help with the moisture but you really need to get your fuel somewhere else if it's an ongoing problem.

Also I may have missed it, but did you change the fuel filter after the shop ran the fuel system cleaner through it? If not, the black could be the varnish like sludge that the treatment cleaned out. I would change stations & begin using a gasoline that has a high detergent content & change the fuel filter again after a month or two as suggested earlier.

The fuel mileage increase was from the improvement of the fuel injector spray. If it sprays in globules instead of an even mist you will get crappy fuel mileage, that's why cleaning them is a good idea & your O2 sensor has a lot to do with fuel mileage too b.t.w. Have it changed if you haven't yet.

Goth · « **Reply #10 on:** May 22, 2006, 10:36:33 PM »

Two things to avoid. Never fill up after they pump fuel into the ground tanks, stirs up the sediment that may be in it. Also never run your tank low as you will have sediment in there and it will get into your fuel line.....could be old wives tales, but what the hell....

Angus · « **Reply #11 on:** May 23, 2006, 04:09:19 AM »

Fuel filters are rather easy to change and on many cars you could add one.
And check your airfilter too

SaburoS · « **Reply #12 on:** May 23, 2006, 04:58:22 AM »

Since you didn't mention it, did you have the Spark plugs, wires, PCV valve, and air filter checked as well?
Run an OBD-II code scan to eliminated your sensors from the picture.

Airscrew · « **Reply #13 on:** May 23, 2006, 08:45:04 AM »

Thanks for all the comments guys
Brenjen - the shop ran the fuel system cleaner about two months ago but they didnt have a fuel filter for my car in stock. I just had the fuel filter changed last saturday, thats when I saw all the black cruddy water/fuel in the filter. I have considered the possibility its just left over crap when the system was cleaned.
I havent considered changing the O2 sensor, the car only has 38,000 miles on it, and 28,000 I put on it this year since I bought it.

Goth - yes I try to avoid pumping my gas when the trucks are there filling the stations tanks, on the other hand I quite regularly run my tank (16 gals) down to about 3 - 4 gal before I fillup depends on my mood. thats a habit I may have to stop

Angus - yes some fuel filters are easy to change. On my car the fuel filter is near the gas tank. With fuel injection you have to depressurize the system and that takes extra care and time to not screw it up. I had the filter and the guy at the shop changed it for free, no charge cause I'm a regular customer

SaburoS - the car has been running fine all year, just two months ago it started acting sluggish at 50-60 mph (about 1500-2000 rpm's) the faster I tried to go the more it would seem to bog down, then after a few minutes all would be fine. when I had my oil changed I asked them about it and they ran the fuel system cleaner, all was good, car ran fine and gas mileage improved. car has 38,000 miles, spark plugs, air filter, and PCV were changed at about 15,000 miles. I'm thinking about the spark plug wires but wasnt worried about them because I inspected them and found no cracks in the insulation and the boots all look good.

Now that i think about it, my problem started two months ago when the car started running poorly, and that is probably when I got the bad gas, or else accumulated enough water in the tank to cause a problem.
I'll run some STP or denatured alcohol in the tank for the next couple of fillups and then change the fuel filter again. If its still bad I may just take the car to my brother-in-laws shop and pull the gas tank and drain and clean

It wouldnt be that hard for me to get samples from each of the gas stations I use so i know which one to avoid in the future, one of them may have contaminated ground tanks

Brenjen · « **Reply #14 on:** May 23, 2006, 04:39:44 PM »

The black was more than likely from the treatment from what you stated & that's good, it means it worked. O2 sensors are notorious for causing these sorts of fuel mileage going to crap problems, they're affordable, change it.