jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
  
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| FBH Weird Start Up Spitting Sounds and Flame Out - FIXED! |
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Hi all,
I'm pulling the remains of my hair out with this one.
The D3 is a 2009 model and I haven't been able to get the FBH to start since I first bought it in Feb of 2018.
Just yesterday I installed a complete new burner unit (£185 including glow plug) and the two sensors, in to the heater and a new pump was fitted last year.
With the diagnostics attached (v2.14 and 2.16), the heater goes through the startup procedure and appears to start. Clouds of smoke at first (presumably from diesel on the glow) and eventually the Flame Detect light comes on in the software.
Then as the heater starts to come up to speed I hear slightly alarming spitting and spluttering sounds and it eventually flames out. Sometimes with a Flame Out fault code and sometimes without any code.
Here's a video from today so you can see what I mean. There is some passing traffic in the background but I think you should be able to hear the spluttering OK).
Does anyone have a clue as to why it does this please?
Many thanks,
Last edited by jonathanrichards on 9th Jan 2019 10:46 pm. Edited 1 time in total
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 2nd Jan 2019 6:11 pm |
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yogi972
Member Since: 05 Jun 2011
Location: Kineton
Posts: 3372
 
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I had this the other week with my folks d3
I used an airline down the air intake on each start up, (using the gap Bt tool)
And loads of smoke would come out, I did this about 6 times as I suspected crud in the fbh burner as it was dripping unburnt fuel from the exhaust.
Previous owner had unplugged the unit, insuppose to save fuel 
Upon 7th attempt onwards, it would run a full cycle without added air 
It’s been running fine ever since and not thrown any codes.
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| 2nd Jan 2019 6:56 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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I think you may have an issue with air bubbles in the fuel line and the spluttering you are hearing is the flame jumping as air pockets in the fuel reach the burner. Take the fuel line off at the heater end and submerge in a small cup of diesel, do a fuel prime for at least 30 secs and see if you keep getting air bubbles forced out. The better way would be to insert a small piece of clear Webasto fuel line between the existing fuel line and the heater to check for bubbles but I assume you don’t have any of that to hand.
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| 2nd Jan 2019 7:14 pm |
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jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
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If I remove the fuel line and check for bubbles, how do I make sure that when I then return the pipe to the heater, there isn't any air in the line again??
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| 2nd Jan 2019 9:42 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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The heater fuel line is self bleeding (by starting the heater) and once free of air it will remain free unless you have a leak.
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| 2nd Jan 2019 10:36 pm |
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jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
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So just keep pumping (using the Component Test feature in the software), until no bubbles are present in a container?
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| 2nd Jan 2019 10:39 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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You will see one of four things:
1. it will be free of air right from the start
2. There will be air bubbles to begin with and they will eventually clear and never return
3. There will be air bubbles to begin with and they eventually clear - after a period of time (hours/days) the air returns - you have a slow leak
4. There will be continual air bubbles that never fully clear - you have a big leak
Prime the fuel pipe into a container, never with it connected to the heater. Submerge the end of the fuel line under the level of diesel in the container so you can witness the air bubbles. Once you are bubble free you should be good, connect back up to the heater and start it - hopefully all is well.
If you have been priming the fuel line for well over a minute and still seeing lots of air you have an issue. One main trouble spot where air can leak in is where the fbh fuel line connects to the top of the tank sender unit. You can use the component test to prime yes, I can’t remember if the proper fuel prime function works with the LR fbh it has been a while since I have messed with one on diagnostics.
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| 2nd Jan 2019 11:00 pm |
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jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
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Right. OK.
That looks like tomorrows mission for me then.
Many thanks for your help!!
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| 2nd Jan 2019 11:55 pm |
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jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
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Bit of an update.
Today I ran the fuel pump for about a min and submerged the end under a pool of diesel in a jar. A few bubbles came out.
Then the heater ran and achieved full load for about 30secs. But I then started to hear the flame spluttering in time with the fuel pump ticking. Then it flamed out.
Tried several more times and still getting that spluttering in time with the pump thing, as well as flame outs.
What's stopping me temporarily running some fuel pipe direct from the pump under the car, straight to the FBH to isolate the possibility that the FBH fuel line might have an air leak in it?
Also, do I need to out a Jubilee clip on the fuel pipe at the FBH end, because at the moment it's only secured with a tie-wrap.
Thanks,
J.
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| 3rd Jan 2019 5:33 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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You can for sure run some fuel line to bypass the existing fuel line, but you need to ensure it is Webasto fuel hose as it is a specific diameter and would affect the amount of fuel delivered if you use a different size. Also note eberspacher fuel hose is a different size again (smaller) so it has to be Webasto stuff.
I would get a clip on there, just helps keep everything secured especially when there is fuel involved. It isn’t under any pressure and is unlikely to leak fuel out or air in unless the rubber joiner is knackered but should have a clip on.
Sounds like you are going in the right direction, does it not normally reach full load before cutting out?
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| 3rd Jan 2019 9:08 pm |
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jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
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Good info!
I've ordered this from Butler Technik
https://www.butlertechnik.com/webasto-heat...84032-p152
So I will bypass the LR fuel pipe.
I have my suspicions as this vehicle had a re-con engine fitted in 2015. I found that the +12v feed from the FBH to the pump was broken and I had to thread a new wire to the pump in order to clear an open circuit fault. So maybe they also kinked the fuel line at the time when the body was refitted after the engine job?
If the fuel line is compromised I have no clue if it's at all possible to route a new fuel line to the FBH with the body in place?
What do you think?
To answer your other question: No, it never normally gets to full load before it cuts out.
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| 3rd Jan 2019 10:08 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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That will do perfect
Every possibility they may have damaged something then. As I said before the most likely air leak spot was the top of the sender, so on the inlet side of the fuel pump. This was more common on the jag XF though which shared a very similar setup. Maybe they hadn’t seated the rubber elbow properly on the sender or haven’t refitted the clip? If you’re getting air in you are more likely to have an air leak pre pump rather than post but your fuel line will help you diagnose either way.
If you have no joy substituting the line from pump to heater, put it back to stock and then connect the suction (tank side) of the pump to your new line and put that into a jerry can or something to rule out the suction side.
If your new fuel line from pump to heater cures it, I would just install it as neat as possible cable tieing the line to existing wiring harnesses and other points (avoiding brake and fuel lines if you want to be by the book).
Sounds like decent progress then, the thermo top V is VERY sensitive to air in the fuel.
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| 3rd Jan 2019 10:47 pm |
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jonathanrichards
Member Since: 11 Jan 2018
Location: Hull
Posts: 148
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Alright. Sounds like a plan.
Next week I'll try both sides of the pump.
What is the suction side like to fix though?
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| 3rd Jan 2019 11:00 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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I can’t remember the exact setup as it enters the tank but there is a 90 degree rubber elbow that pushes onto a nipple on the top of the tank and in the other end is the fuel line to heater. It’s that connection where the rubber joiner pushes onto the nipple on the sender that can leak air in. Make sure it’s well seated and has got a clip tightened well around it. Should be simple enough to sort, just access isn’t great.
Best of luck with it!
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| 3rd Jan 2019 11:21 pm |
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Nc1989
Member Since: 28 Apr 2015
Location: Doncaster
Posts: 202
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A post halfway down page 3 of the thread below shows the sender and the fbh connection. Maybe you have to drop the tank slightly to reach the sender, I must have been thinking of something else where you could reach the sender in situ sorry. Your fuel line test will show if the leak is pre or post pump without having to drop the tank though.
https://www.disco3.co.uk/forum/faulty-low-...93-30.html
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| 3rd Jan 2019 11:27 pm |
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