Vito 638 fuel question

[Kingswood636]

Hi iv just replaced the seals on my fuel pressure sensor on the end of the fuel rail. Everything went pretty well. I had read that sometimes you might need to bleed the fuel lines. So was surprised it started up straight away. After it started it started puffing a lot of white/grey smoke. Almost like steam.

Went back under the bonnet and checked everything was alright. All looked ok. Apart from on the left hand side of the engine I think it's the fuel filter the middle of the three fuel lines has rushing air bubbles through it

Is this normal?

What could I have done wrong?

Thanks Dave

 

[Kingswood636]

Up

 

[StMarks]

No this is not normal Kingswood636 (as in Kwacka?).
IMHO it's symptomatic of a leak into the fuel line system. Fwiw I had this problem on my vito, and eventually discovered that it was the pipe between the high & low pressure pumps. It had been poorly placed by a previous owner & one of the pulley wheels was touching it & had rubbed through. Just a pinprick, but it was enough.
I had a friend with the same symptoms, except on his we eventually discovered that it was a damaged O-ring on the plug-in pipe connector onto his fuel filter.
Hth.

 

[Kingswood636]

Ok cheers for that. Yes as in Kawasaki. I ride a 04 636.

I was told by my mechanic it might be a leaking injector. So borrowed his leak test thing and have 1ml difference on the 3rd from the left. Would this be enough of a leak to cause a problem?

Thinking about getting a refurb done on them all. What sort of money would I be looking at?

 

[StMarks]

I've sold my Vito now, I only brought it as a trackday transport vehicle for my (636 beating ) Daytona.

Fwiw I wouldn't expect a leaking injector to be able to introduce that much air into the system. However that is only speculation, hopefully there will be a knowledgeable expert on here who can that clarify for you.???

...Thinking about getting a refurb done on them all. What sort of money would I be looking at?

Once again, outside of my scope of knowledge, sorry.

 

[Kingswood636]

Haha yeah the daytonas are nice bikes. Not actually had mine on the road this year.

Ok well thanks for your help. I'll try and go over the fuel lines and see if I can see any rub marks that might have caused a split.

 

[StMarks]

Fwiw I would suspect it is far more likely to be a damaged rubber o-ring on one of the push in connectors.

Shame non of the Mercedes Diesel experts on here will take the time to offer their more qualified advice.

 

[Kingswood636]

Yes I was quite surprised there wasn't more advice offered.

It's just odd as I only changed the O rings on the fuel pressure sensor. Didn't touch anything else.

Oh well the joy of it.

 

[Danny DeVito]

Why did you replace the seals ?

 

[Kingswood636]

When i had it scanned it came up with the code for the fuel pressure sensor and had read that it's normally just the seals. So went for that option.

 

[Kingswood636]

When I had it scanned it came up with the code for fuel pressure sensor and had read that it is normally the seals. So went for that option.

 

[Danny DeVito]

And why did you have it scanned ?

 

[Kingswood636]

It has been going into limp mode for a while. And over the last week or so had been cutting out completely with the EDC light coming on. The main reason it was goin into limp mode was because of the main vacuum sensor on the bulk head. I have replaced that with a proper merc one and when I drove it round the block it didn't seem to go into limp mode. But had a lot of white smoke coming out the back. A whole street full lol

 

[Danny DeVito]

Are the bubbles gone ?

 

[Kingswood636]

Last time I ran it no. There were still air bubbles in the middle pipe on the fuel filter. I have been told that this is normal tho. Is there a proper way to bleed the system if this isn't right?

 

[Danny DeVito]

No bleeding is needed ever. Air bubbles cant be right. Try get rid of them somehow. Air leaks will interfere with fuel rail pressure

 

[StMarks]

Last time I ran it no. There were still air bubbles in the middle pipe on the fuel filter. I have been told that this is normal tho. Is there a proper way to bleed the system if this isn't right?

Once I had resolved my damaged pipe issue, mine ran totally clear with no air bubbles whatsoever.
Like ways my friend with the damaged O-ring.

I believe the system is a recirculating system, and it should therefore be self bleeding.?

Hth.

 

[StMarks]

Sorry DDV, I was writing that whilst you were posting.
Didn't intend to parrot you mate.

 

[Kingswood636]

Ok cheers for all the help guys. What is that middle pipe for?

 

[Kingswood636]

Ok so went up to the van last night and got it all back together. It is still smoking but not as bad it seems. Still too bad to drive tho. I noticed the fuel light was on as well. So going to stick some more diesel in it today. See if that can help bleed the system.

Are there any other ways to bleed it. If that doesn't work?