Member Since: 11 Aug 2007
Location: Isle of Wight
Posts: 19
FBH Possible air leak
Possible air leak?
I have read many threads on this forum about the fuel burning heater or FFBH (fuel fired booster heater) as Land Rover call it. Over a number of weeks with the help from this forum I have fitted an oval timer and a remote which work great, and many thanks to those who have written about them. Now I have the ability to flash up the FBH with the touch of a button I think that I may have uncovered a fault with my FBH which others may also be experiencing? Having played about with my FBH I think there is a problem with air entering the fuel line somewhere between the FBH fuel pump and the fuel tank or inside the tank? I am aware of the problems with running the fuel collection pot dry in the tank which I believe is possible if the fuel tank is low on fuel especially if the vehicle has more than a 5degree lean in any direction and the FBH is run for longer than 30 mins. The reason I think that I have a potential air leak is because I only get reliable start ups when the fuel tank is full. When the level of the tank drops below ¾ full I start to get lots of failed starts, fan kicks in, fuel pump starts, puffs of smoke, fan speeds up fuel pump shuts off, FBH goes into shutdown cycle. Not only dose it do this with the remote but also when the car demands the heater to light and when the fuel level is down to ¼ of a tank she will not light even after numerous attempts! I have had more lockouts these last few weeks than I care to remember!! When I top the tank up and reset the FBH It will not light for about the first 6 or so goes which I think is the pump bleeding the system through , but once she has lit its fine and will re-light again and again until the fuel tank level drops again. I know there is a non return valve in the SU type fuel pump so I believe the problem is aft of the pump. I have had a chat with Webasto and they also think it is a fuel problem and that some early D3s had air entering the fuel system somewhere around the tank area. I am not sure what the fix is and was wondering if anyone out there has had theirs fixed by Land Rover or if any one has had their fuel tank apart or am I going to be the first
PS for those of you who are not sure about your heater not working, when mine is in lockout mode and either the car or the timer is calling for heat in the first few seconds you can just hear a few clicks from inside the FBH unit. (You may have to put your ear right on the unit, but be warned it may be hot!!) I have found that by just disconnecting the power will not reset the FBH from this lockout mode. With mine to reset the FBH You need to pull the fuse out at the same time the FBH is making the faint ticking sound and keep it out for about ten seconds and then repeat. After the second attempt it should light on the third. If you do not use or do not have the oval timer to demand the heater to light you will have to start and stop the engine each time and as you probably already know the car will only try and light the FBH if the outside temp is below 5c and the coolant temp is below 75c.
Sorry for the ramble.
6th Jan 2009 8:31 pm
wiggs
Member Since: 03 Sep 2006
Location: Manchester
Posts: 14368
Welcome to the site
You could well have stumbled on a problem there ...
Perhaps any one who is having difficulties with there FBH should also list what the fuel level of there car was at the time ...it may help to get to the root of some of the problemsG4 Gone ...but not forgotten
7th Jan 2009 1:19 am
Howard2
Member Since: 11 Aug 2007
Location: Isle of Wight
Posts: 19
Hi Wiggs,
Yep I think there are a number of people out there having problems with their FBH's and it sound like they are replacing them when perhaps all they need are a reset Went out last night and FBH would not light on first go, I think the fuel is running back into the tank over time and when I come to light it up its pulling air up the pipe fuel, tank is only just of full mark. The only sure way for me to prove this theory will be for me to run the unit off a fuel can which I shall try in the next few days
7th Jan 2009 10:06 am
wiggs
Member Since: 03 Sep 2006
Location: Manchester
Posts: 14368
Good idea G4 Gone ...but not forgotten
7th Jan 2009 10:10 am
10forcash
Member Since: 09 Jun 2005
Location: Ubique
Posts: 16534
The shutdown procedure for the FBH is to shut down the fuel pump first to purge the burner, on startup, the pump runs to re-pressurise the fuel line prior to the burner & ignitor being triggered
7th Jan 2009 3:50 pm
Howard2
Member Since: 11 Aug 2007
Location: Isle of Wight
Posts: 19
Hi Ten4,
Yes full understand mine will often switch the fuel pump off during the start up procedure and then go on to its purge mode ready for the next restart One of the reasons I think it does this is if there is insufficient flame in the burner pot. I could be wrong but I think that when the heater plug switches to flame sensor if there is an insufficient delivery of fuel during the start up procedure purge – then the flame sensor will shut the fuel pump down because it detects a flame out. To be honest mine is so unreliable to light on the first attempt it’s a waste of time setting the timer. As I’m sure you know it’s very odd and annoying to have an intermittent fault When she actually lights with the car calling for heat she works fine fully modulating and all Thinking out loud do you know if the tank is well vented only I wonder if, when the car is driven and then stopped could there be a partial vacuum in the tank which in turn, could pull fuel back if there was an air leak
8th Jan 2009 1:20 am
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
You could take the fuel cap off to prove/disprove that theory.
I have to say though, my fbh does suffer a fair few false starts when the remote is used. It worked fine this morning with the tank 3/4 full. I'll monitor the situation and see if I can reproduce the low fuel theory (obviously not so low as to have the fuel light on).
8th Jan 2009 7:34 pm
DiscoDunc
Member Since: 08 May 2006
Location: Bristol
Posts: 16390
mine seems to work ok on remote, gsm and timer even when the tank is about 1/4 full. was about 1/4 this morning and worked ok. sent a text message from swindon whilst on the train this evening and lovely and warm when i arrived at Bristol Duncan
-----------------------------------------------------
If I'd known I was going to be so thirsty this morning I'd have drunk more beer last night.
FFRR Autobiography 4.4 SDV8 MY17
D4 HSE MY13 SOLD
FFRR 3.6 Vogue TDV8 SOLD
D4 HSE MY10 SOLD
D4 SE TECH MY15 SOLD
D4 XS MY12 SOLD
D4 HSE MY10 SOLD
D3 HSE MY06 - Re-Cycled Worldwide
8th Jan 2009 8:48 pm
wiggs
Member Since: 03 Sep 2006
Location: Manchester
Posts: 14368
Same here duncan
Never had any of the problems others seem to be having with the FBH G4 Gone ...but not forgotten
8th Jan 2009 9:27 pm
Howard2
Member Since: 11 Aug 2007
Location: Isle of Wight
Posts: 19
Well it was a good experiment. Put fuel can in the spare battery compartment, so pump had plenty of head but made no difference I have had just as many failed starts running the FBH from the can, so it’s not an air leak causing the problem. In actual fact I would say that only 4 out of 10 start ups are successful. When I reset the FBH she will normally light twice either with the car calling for heat or the timer, but any more than that she will blow herself out Very odd, I have disconnected the timer and put everything back to standard and then reset but still not lighting consistently. Gareth, when yours fails does it seem like the fan is kicking in to fast and knocking the flame out And have you had a number of lockouts
9th Jan 2009 8:25 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
I have never had it lock out on me, but sometimes when I press the remote, the fan starts, I hear the clicking but it shutsdown after a minute or so without lighting at all.
9th Jan 2009 8:28 pm
Howard2
Member Since: 11 Aug 2007
Location: Isle of Wight
Posts: 19
So do you not get any smoke out of the exhaust when it fails to light
9th Jan 2009 8:54 pm
Gareth Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26702
No smoke on a failed start. Plenty on a good one.
9th Jan 2009 9:08 pm
Howard2
Member Since: 11 Aug 2007
Location: Isle of Wight
Posts: 19
Ok so when yours has a failed start does it go into another start sequence by itself
Unless I've missed it no one seems to have asked this question, is the vehicle left parked level, as you can see from the following LR instructions the FBH shouldn't be used if the vehicle is parked with the front or right side up at an angle greater than 5 degrees:
Click image to enlarge
I believe this is due to fuel starvation occurring if it parked in these orientations at angles greater the 5 degrees.LRs are a fond memory, apart from the maintenance.
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum
When I top the tank up and reset the FBH It will not light for about the first 6 or so goes which I think is the pump bleeding the system through , but once she has lit its fine and will re-light again and again until the fuel tank level drops again. I know there is a non return valve in the SU type fuel pump so I believe the problem is aft of the pump. I have had a chat with Webasto and they also think it is a fuel problem and that some early D3s had air entering the fuel system somewhere around the tank area. I am not sure what the fix is and was wondering if anyone out there has had theirs fixed by Land Rover or if any one has had their fuel tank apart or am I going to be the first 
Went out last night and FBH would not light on first go, I think the fuel is running back into the tank over time and when I come to light it up its pulling air up the pipe fuel, tank is only just of full mark. The only sure way for me to prove this theory will be for me to run the unit off a fuel can which I shall try in the next few days 
One of the reasons I think it does this is if there is insufficient flame in the burner pot. I could be wrong but I think that when the heater plug switches to flame sensor if there is an insufficient delivery of fuel during the start up procedure purge – then the flame sensor will shut the fuel pump down because it detects a flame out. To be honest mine is so unreliable to light on the first attempt it’s a waste of time setting the timer. As I’m sure you know it’s very odd and annoying to have an intermittent fault 
When she actually lights with the car calling for heat she works fine fully modulating and all 
Thinking out loud do you know if the tank is well vented only I wonder if, when the car is driven and then stopped could there be a partial vacuum in the tank which in turn, could pull fuel back if there was an air leak 
Very odd, I have disconnected the timer and put everything back to standard and then reset but still not lighting consistently. Gareth, when yours fails does it seem like the fan is kicking in to fast and knocking the flame out 
