SL 320 idles fine for 15 minutes - not fuel filter

[Mal]

I was driving had about 6 gallons of gas it started to sputter the slowed and slowed and slowed till stop. I would start it it would idle but not rev above 2k without sputtering. At 2k it would sputter. This would last 10 minutes then it sputtered so much it wouldnt run at all.

wait 30 minutes. All over same thing. Seem to idle fine, not rev high and then slowly increasing sputter till dead.

I had been hearing an odd eletric sound in the back..

I changed the fuel filter and changed the plugs. Plugs looked awesome textbook proper plugs. No crud at all came out of old fuel filter.

Start it up it idled perfect for 15 minutes, then slight sputter, then increasing sputter, 2 minutes, it got worse 1 min worse till wont start.

I would think a faulty fuel pump it wouldnt start at all.

I would think fowled injectors would be a consistent sputter and not go from smooth to worse to bad.


q's:

1) how to tell if bad tank of gas?

2) how to tell if sabotaged like sugar/sand in gas?

3) what could it be?!

[ctaylor738]

There is a strainer in the fuel tank where the main fuel line attatches. It is highly possible that it is clogged and only allows a small amount of fuel through. The noise you hear may be the pump straining because it cannot pull fuel out of the tank.

You might also have a plugged fuel tank vent. Try removing the filler cap when the engine starts to die and see if that changes anything.

[Mal]

That sounds totally logical.

So I started her up and as usual ran fine. I waited and waited and waited. I gunned it past where it normally bogs around 3k. Nothing. I waited some more. 20 minutes never started to die. :/ No opportunity to pull gas cap.

Had to go - so tomorrow morning I will see If i can get around the block.

[Mal]

Started her and she idled perfectly for 15 minutes or so. I back her out and on the way in from going around the block she starts to bog down after I tried to go faster. Around 2 or 3k. I get in front of my house and she quickly begins to run horribly rough. I race around the back and pull the gas cap. No whoosh or vacuum build up. But I did see the area to be wet from gas. Idk if its just normal gas fume wetness or some kind of backup.

Im inclined to change the fuel pump but it sure makes no sense that it would idle fine for so long if it the fuel pump was bad....

[ctaylor738]

Like I wrote earlier, check the tank strainer. IME fuel pumps either work or not, they generally don't peter out after running for a while.

[Mal]

Originally Posted by ctaylor738

Like I wrote earlier, check the tank strainer. IME fuel pumps either work or not, they generally don't peter out after running for a while.

Yea I would think it would just go out period. Ok tank strainer. Next project.

Presumably the tank strainer is in the bottom of the tank. Taking out the gas tank always fun. Any diy threads/photos anyone can recommend?

[tecqboy]

If you don't find any crud plugging the strainer....Long shot; check the crank position sensor. Some have been known to become heat sensitive. On the 6 cyl. it's on the front near the idler pulley and easy to blow some cool compressed air on it to cool it down.

[duxthe1]

The sensor up front is just a diagnostic sensor. The crank sensor is in the back of the engine, in the bellhousing, behind the oil filter housing. Not easy but the 129 has more room than most.

[Mal]

Im sure theres crud in the strainer. Im not sure thats the problem but im sure there crud in the strainer. Before I bought the car it sat in a lot uncovered for several years plus Ive run it near E often one too many times. So strainer in bottom of tank right.