280sl will not run hot

[280 roadster]

I have hot running problem with my 280 sl ,

It has been sitting 10 years

   starts nice cold
   Runs  idles “very” nice during warming up
   As it gets to running temp it starts to miss a little
   When hot will not idle starts to splutter , no throttle response
   If hold around 3000 rpm (hot ) it splutters and coughs
   It gets worse as it gets hoter till it wont run

I was hoping you may be able to help with some ideas.

I have changed

   Plugs & points
   Fuel filter (lots of fine dirt)
   Taken in tank filter plug out (as not Bad)
   Taken the warm up control out and tested it ( measures 11 mm cold & 14mm hot)
   Turned the mixture knob on the back of fuel pump “in” two turns

[ja17]

Hello,

Still sounds like a fuel delivery problem.  If the intake to the flower pot in the tank is blocked, the engine will start and run until the small amount of fuel in the flower pot is used up. Then it will run out of gas. After sitting, eventually fuel will seep into the flower pot again. The cycle will repeat itself unless the plug is removed, or you add enough fuel to the tank so that it flows over the wall of the flower pot. Study the "fuel tank tour" for a good understanding of this complex tank.

I would make sure you have at least 3/4 tank of fuel or remove the fuel sender and examine the inside of the tank to make sure that the flower pot passage is clear.  Also think about checking the screen in the electric fuel pump intake.

Check the fuel volume and pressure when your car is hot and the problem is occuring will also help diagnose a fuel problem.

If your engine has air, fuel, spark on time and compression it will run. My first guess is you have a fuel problem.

Keep us up to date.

[280 roadster]

thanks for you help - your correct , i have problems with the fuel not getting into the pot as it was very gummy & rusty , but the pot also seems to be breaking down with white hair / flake bits at random coming out after i have been trying to clean rinse. with the tank out i have had it filled  with water to almost the top of the pot but the pot only seems to have a few inches in it " seems odd as water / fuel should level up . if i take the plug out the two inches in the pot drains and then only trickles out as the water makes its way into the pot area !

[Iconic]

As far as what you are describing with the flower pot not getting fuel/water from around, if I understand correctly, this is covered in the Tech Manual. There is a square hole which the fuel return line runs through to get into the flower pot. Of course the line is round, so the clearance between the round line and the square hole provides a path for the fuel to "equalize" to the inside of the flower pot as fuel is used from the inside of the flower pot. This can be cleared with a hanger (I believe, as I didn't need to do this). But, if there is lot of gunk in your tank, it could block the flow again.
Prior to removing the tank, how much fuel was in it (approximately) when you were having your hot running issues?
If it was above the top of the flower pot, you have more things to be concerned about, because if the fuel level was that high, it had a clear path to the screen without having to go through the square hole .... either way, the fuel does need to get through that square hole.
I hope this helps.
Mark

[ja17]

Hello,

As mentioned, the entrance to the flower post is small.  You will not have a large volume of fuel draining out ot the tank after the fuel level becomes lower than the flower pot. However it must be clear enough to supply sufficient fuel to the electric fuel pump.  Denatured alcohol is a good tank cleaner.  It desolves old fuel varnish better than anything else.

[tel76]

Hello Joe,
Can you please explain what Denatured Alcohol is and who would supply it.

[ja17]

Hello Eric,

You may have a different term for denatured alcohol in the U.K.  Here in the US it is a common form of unpalatable alcohol.  I have also used Isopropyl alcohol, a common disinfectant used in hospitals and doctor's offices.   It is readily available in paint stores, home improvement stores and drug stores in the US. It is actually fairly inexpensive and common. Read more detail at http://en.wikipedia.org/wiki/Alcohol

Many shellacs and varnishes are easily dissolved or thinned by alcohol based solvents which make them perfect for disolving varnishes left over from dried out gasoline (petrol).

[Garry]

Eric,

Joe may be referring to Methelyated Spirit or White Spirit

[Naj ✝︎]

Yes, He is 

http://en.wikipedia.org/wiki/Denatured_alcohol

naj