vacuum in IN fuel line W124 E300D estate

[SilverSaloon]

hi

my E300D suddenly wouldnt start the other day. I got it started by running it direct from a bottle of fuel and back onto my garage.

anyway, now i've attached a pipe to the metal fuel line IN connection in the engine bay (where the rubber pipe usually connects to), and when sucked it holds a vaccum and you cant get any fuel to come out.

i've taken out the pressure release valve on the drivers side of the fuel tank and thats fine, and i have also removed the in-tank fuel strainer and it is also fine and clean. i have also removed the fuel filler cap.

and it still happens. i assume therefore there is a blockage between the end of the pipe in the engine bay and the fuel tank end.

is there anything that could be restricting it here? i have read about a charcoal canister - does the diesel multivalve have one of these? its definatly not been changed in 70k if it has since i've had the car.

any advice would be appreciated.

thanks

derek

 

[Druk]

Is there a section of rubber anywhere joining the metal pipe to the tank? Maybe it's collapsed internally? Even if there is a charcoal canister, don't know , they fit into the tank breather circuit to capture fumes. How about some compressed air down the pipe. You've not grounded on a speedhump and crushed the pipe perchance?

 

[SilverSaloon]

car was driving fine when i parked up.... next morning, it wouldnt start.

i'll check the pipes between the tank and the main metal ones that run along the body underside....

 

[Olivier]

What were you doing sucking on those pipes
As Druk suggested, you might have a bad rubber pipe, and compressed air would clear any blockage on the hard pipes and the rubber pipes but if you have a soft rubber pipe it won't solve the bugger as the air will inflate it, not like the pump that suck on it and make it cave in.

 

[SilverSaloon]

What were you doing sucking on those pipes
As Druk suggested, you might have a bad rubber pipe, and compressed air would clear any blockage on the hard pipes and the rubber pipes but if you have a soft rubber pipe it won't solve the bugger as the air will inflate it, not like the pump that suck on it and make it cave in.

i've not checked the pipes. i'll take a look at them tonight. I cant blow down the pipe either (myself that is not compressed air) but i guess that would be hard anyway because of all the fuel the other end.....

i'll check the pipes thisevening - its something i wanted to replace anyway as its the only rubber fuel pipes i've never replaced. I am hoping i can remove the pipes and then as i'll have an open end on each end of the metal pipe i can diagnose whether there is a blockage in it or not by sucking - in theory it should be "free".

by the way sucking on that pipe makes you sick.

 

[bolide]

Have you been using comedy fuel?

Nick Froome
the independent Mercedes Estate specialists

 

[nick.ged]

try removing the fuel cap, leave it off, and crank the engine.

had a peugot d that did same thing, blocked tank breather

 

[Druk]

Have you been using comedy fuel?

I never thought of that.

Maybe there's a chip buttie stuck up the pipe?

 

[SilverSaloon]

Have you been using comedy fuel?

Nick Froome
the independent Mercedes Estate specialists

oh yes!! :bannana: its not had much else for 60k

haha, yes maybe a chip or a beansprout is lodged neatly up the fuel line

i've already removed the cap - is definatly a blockage somehwere between/in the tank to the end of the pipe - car runs fine when the pipe that connects to the engine end of the metal pipe is dipped in a bottle of veg oil. (no diesel here thanks!)

 

[bolide]

Maybe a rubber section has swelled due to the alternative fuel & has blocked the fuel flow? Though I would expect it to be hard pipe all the way from the tank to the engine bay. There must be a flexi between the fuel pickup and the hard pipe - what's that like?

Nick Froome
the independent Mercedes Estate specialists

 

[SilverSaloon]

yes its a metal pipe that runs along the underside and a rubber pipe that joins this to the tank. its that rubber pipe i will inspect/remove tonight to see if there is a clog in the metal pipe or on the tank-side

 

[SilverSaloon]

OK i've fixed this last saturday.

i removed the rubber pipe that goes from the fuel tank to the main metal pipe that runs along the underside of the car. Rubber pipes here were fine by the way.

i then sucked on the pipe which was now open on both ends. still held vaccuum, so the blockage was in that pipe.

the pipe itself looks fine from the outside - no damage.

so i got a bicycle pump and attached it to one end and then pumped air into the pipe. after a bit the blockage must of shifted and it was then free to blow air completely through.

i dont know what was blocking it - in hindsight i wish i had put a little plastic bag on the other end to catch the debris.

i then blew air through for a bit longer, both ends and then reconnected everything up, and after a lot of cranking, and some battery charging... the car started, and has been fine since.

I can only assume it was some bad fuel or something that had gone solid in the pipe overight.

i drained the tank down at the same time and the fuel strainer inside the tank still looked brand new (i replaced it Summer 2008).

happy veggin'

 

[trapperjohn]

Note to SilverSaloon's self.

Must pack bike pump, axle stands, coveralls and battery charger for next holiday in case this happens again when I'm in Cornwall towing my caravan.

I'm sure you enjoy tinkering with veg fuel Derek and all the gentlemen's round things that go with it. Such as carrying spare fuel filters - just in case one blocks up. It certainly would not float my boat but Good Luck to you. Perhaps the next mod could be outboard fuel lines. You could run them along the inside of the roof rack.

Bah Humbug

 

[SilverSaloon]

Note to SilverSaloon's self.

i'm not worried about that.... been running veg for 60k and its not happened until now.... i'll risk it for the £3k odd i saved in fuel last year

i suspect if it did happen again, all i'd have to do is swap round the feed and return lines in the engine bay. The fuel would push the blockage back into the tank and i'll be on my way.

failing that, there is always the AA who will tow me home