[trapshitkalci]

Hi Guys,

I cannot pour more than 35L fuel into my 1993 r129 SL500.
After I left the car for 6-7weeks standing I saw that my instrument cluster shows I am low on fuel but after started the engine in 3-4seconds the needle went all the way up to between 1/2 and 3/4 level. So I noticed there will be some problems. So I took out the instrument cluster a got it repaired. But the said it should be all right. So it wasn't the instrument clusters fault.
I went to a gas station the other day when I realized I am again low on fuel ( although cluster still shows wrong quantity) and at the gas station I realized I am only able to fill 30-35L fuel into the tank.
As far as I know the capacity is 70L for these cars.
One of my Fuel pump broke down ?
Has anyone got similar problem in the past?

 

[RKH]

Could be problem with the fuel level sensor at the tank ?

 

[bobterry99]

I'm with RKH on this. But theoretically the problem could be the fuel tank gauge in the cluster. To test that there is a diagnostic routine documented here.

 

[trapshitkalci]

Thank you guys.

 

[trapshitkalci]

I still have this issue yes It can be the Fuel Level Sensor [for my 1993 the part number is 1295420004] But what I realiized recently that after filling in 20-30Litre Fuel my car starts falteringly. Maybe Air is in the fuel system and thats why my fuel guage also shows wrong level ? Is there any correlation here ? I've read in an other post : "Just turn the key on/off dont' start[5-6 times] and this will cycle the fuel pump." But this faltering issue only happens when I am in the Gasstation and after I refilled my car.

 

[sushipaste]

Run a big bottle of Techron to see if there’s improvement. Very well could be the fuel sending unit

 

[trapshitkalci]

I took out the FSU today and inspected it. It looks all right. I checked also the fuel level with my fingers(3/4full at the moment) but when it goes down to 1/2 my car rums out of fuel... so gauge is all right, FSU is all right so can it be the FuelPump then?

 

[RKH]

You said "when it goes down to 1/2 my car rums out of fuel.."
Are you saying you car actually stalled and not running even with a 1/2 tank of fuel ?

 

[trapshitkalci]

Yes exactly. And after I fill in 20-30 liter it goes again.

 

[Jim-ML320W164]

Have you also got this problem:

 

[RKH]

Then the problem may be with the fuel pick up point of the fuel pump inside the tank or the fuel pump itself ?

 

[trapshitkalci]

Yes maybe.

 

[RKH]

As it run again after you top up the tank, so you pump should be good and it is just not picking up fuel at half tank, so it is more likely the pick up point issue.

 

[aam]

I suspect that the slash container in the tank is clogged up.
The bottom holes....
Clean the tank.
Regards,
aam.

 

[Jim-ML320W164]

I don't know anything about your car model technically but here's another hopeful guidance...

Some rear-wheel drive cars like my old Jaguar have fuel tanks which straddle the prop shaft like saddle bags.

There is a fuel pipe connecting the two "saddle bags" at their lowest point, which lets fuel from the opposite "saddle bag" tank from the fuel pump to get used. If that pipe gets blocked it stops the fuel in the opposite saddle bag from being used.

But... The one "saddle bag" isn't going to hold 35 litres back.

I'm curious to know the cause.

 

[robm.UK]

... when it goes down to 1/2 my car rums out of fuel..

Sticking non return valve? At 1/2 full, if you remove fuel filler cap, does the car run?

 

[sushipaste]

Just advice, but only ever use shell or chevron gas

 

[trapshitkalci]

Sticking non return valve? At 1/2 full, if you remove fuel filler cap, does the car run?

I will try this out. And maybe I will suck out all the fuel from the car next weekend by removing the FSU and placing there a tube and suck the fuel from there.

 

[Thom_7]

Run a big bottle of Techron to see if there’s improvement. Very well could be the fuel sending unit

I had a malfunctioning fuel gauge also, it would show a near-empty tank after fill-up and be very slow to read full. I did the Techron thing also... took a quart bottle and just poured the whole thing in the tank along with fresh 93 octane.

Let the car sit for 48 hours, and the fuel gauge has worked perfectly ever since.

 

[sushipaste]

I had a malfunctioning fuel gauge also, it would show a near-empty tank after fill-up and be very slow to read full. I did the Techron thing also... took a quart bottle and just poured the whole thing in the tank along with fresh 93 octane.

Let the car sit for 48 hours, and the fuel gauge has worked perfectly ever since.

Good to hear. Just make sure you never let the tank get to less than 1/4 and you use shell or chevron only, forever