Fuel Breather

[Minchetty]

new to this site

Recently purchased a w124 95m 280 estate auto

Suffered from fuel starvation - initially after tank run low.Runs for 20 mins then dies. If i take off fuel cap can restart and runs for a few minutes.(can't restart for ages if cap on)

Can't take it to MB dealer as too far away

Local garage have replaced fuel filter, fuel pump and fuel pump relay

Have an OVP relay arriving today. Have posted on MBClub forum as well. Feeling is that it could be fuel breather blockage. Do these have a filter on them or are they just a hose to the tank?

Any thoughts?

Thanks

 

[wscheffer]

Does the cap have excessive pressure being released when taking it off, might be a collapsing tank issue.

When was the last time the charcoal filter was changed?

 

[Minchetty]

Thanks

Thanks

Fuel filter
Fuel pump
Fuel pump relay
OVP relay
All replaced
MAF seems clean

I am thinking that it must be fuel tank related
It first started after the tank was run low. Runs for 20 mins then starved of fuel. If I take the fuel cap off I can restart and then she runs for 5 - 10 mins.
If I leave the cap on run the engine for a bit and then take it off the tank sucks in air.

Where do i find the charcoal filter?
Is it safe to take off the tank and clean out, or would it suffice to syphon the tank and hope that any muck comes out (use garden hose?)

Thanks

 

[wireman]

You will struggle getting the tank out of a 124, seems like they built the car around it.
If you have a charcoal filter (compulsary in US) it is in the breather pipe from the filler neck, usualy black about the size of a coke can with two pipes, inlet and outlet. Overfilling the tank can destroy the filter, I am not sure that it would block it though. There is usualy some pipe to the outside world on the outlet of the filter placed somewhere near the filler neck under the car, if this is soft material it cold be crushed or blocked by a build up of crud in some obscure space under the car. Some installations are quite complex with pipes all over the shop.
The purpose of the charcoal filter is to reduce the amount of nasty stuff in the vapours that come off the petrol in the tank, the more complex the system the more efficient the filtration.

Have a good look under the car, find the pipe work and make sure that the end is not choked up with mud.

 

[Minchetty]

Thanks

will get a torch and have a good poke around - some other posts seem to suggest crankshaft position sensor could be a culprit, but will check this cheaper option first

 

[Minchetty]

starvation

There was a pipe from the tank into a little white plastic filter thingey - took the off and blew it through.
Put it all back and the car ran for an hour, opened the bonnet and then she died. I then opened the fuel cap expecting an inward suck of air but nothing.

Therefore next thing must be crankshaft sensor? (cutting off fuel pump when hot?) ???

 

[Lordjellybelly]

In view of the above comments is it therefore unwise to fill up to the max. ie past the cut off point of a normal pressurised pump? With my 1996 W124 cab I do tend to do just that. In my previous W202 C240 the fuel gauge would not register if tank filled right up. ..stayed on empty until tank about 2/3 full.

 

[kth286]

Minchetty

The way the engine dies is an indication of whether fuel problem or electric.

If it dies all of a sudden like turning the ignition key off, then likely an electrical problem.

If it splutters to a stop then fuel problem is likely.

The charcoal filter is inside the nearside front wing and the liner has to be removed to get at it. It may never have been changed (every 72,000 miles). It is important to change as they eventually get blocked up and can cause the fuel tank to collapse.

 

[Minchetty]

fuel

Hi David

thanks for your thoughts - it runs absolutely fine and then splutters and cuts out fairly quickly - a dab on the pedal has no effect.

Other posts have led me to think it could be the crankshaft position sensor - cuts the fuel off when hot and will only restart when cooler.

However I have also had a feeling it could be the actual fuel feed in some shape or form. How would I know if the charcoal filtered was goosed? Or is it a case of replacing it anyway?

Thanks

 

[Minchetty]

Success

Fitted new active charcoal
Ran for an hour and restarted immediately!!
However went for a small test run and seemed OK apart from when I kicked down she hesitated a bit and didn't really get going. It may be because she hasn't had a run for a while?

Will go on a proper test on Monday and get a Bosch centre diagnosis if necessary

Thanks to everyone for their input - hopefully it is fixed