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Old 19th June 2018, 18:47   #1
ROD1
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Default Fuel burning heater problem

I have finally installed a new FBH 98570D , which I purchased new from Rimmers two years ago. I tested the new dosing pump on my workbench and it works. I primed the FBH until fuel came out of the pipe next to the FBH, by pulsing the dosing pump with a 12 volt battery.

Initiated FBH startup by 12 volts to pin 1, FBH start sequence begins but does not fire up, as the dosing pump is not pulsing, thus fuel is not being delivered to the FBH, anyone have any ideas as to what the problem is.
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Old 19th June 2018, 19:37   #2
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The model number you quote should have earth to pin 3 to make it start up as pin 1 should be pre populated with the wire that switches the FBH on as a supplementary heater when temperature is 5 or less, so fiirst question is , is pin 1 not populated or did you put another wire in there alongside the pre populated one ?

The dosing pump may work but the FBH will not call for fuel unless conditions are right for it to do so.

The circulation pump should come on a soon as the sequence starts so is it working ?

Start the sequence and time it to see exactly when it switches off and report back

Next thing to check is PCB and glow plug in that order , French Mike on here will check the PCB for you if you send him a pm or he may see this thread and post
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Old 19th June 2018, 21:04   #3
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I tried earthing pin 3 to the securing FBH securing bolts, but it would not start so I placed a wire onto the existing pin 1. By externally priming the dosing pump FBH fires up and produces heat but cuts out when connected to plug.
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Old 20th June 2018, 09:24   #4
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It should work from pin 3 to earth, I would be careful about continuing to prime the dosing pump from a battery as all you are doing is pumping fuel into the chamber and if the FBH does fire up it could go pop or bang !

The reason it doesnt work when the dosing pump is plugged into the loom is because the FBH isnt calling for it as all conditions need to be safe before it will call for fuel, so you have another issue somewhere, you have proved that the dosing pump works so look elsewhere.

If the FBH fails to start after the third attempt it goes in to lock out, disconnect the six pin plug then disconnect and reconnect the power lead (2 pin plug) then reconnect the six pin plug on the FBH to reset. The 2 way connector has to be inserted before the 6 way connector otherwise a chip in the control unit may blow.

In my opinion you need to remove the PCB and get it checked over as it should fire up from pin 3
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Old 20th June 2018, 10:13   #5
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Hi Rob.
What are the chances of the PCB being faulty as the OP says he purchased from rimmers brand new, and as only just fitted it ? therefore not been on a car before, unless the PCB board was faulty from get go.
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Old 20th June 2018, 12:20   #6
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Hi Steve,

I may have mis read the 1st post as I thought it had been running before but now failing, as you say if new PCB unlikely to be faulty but doesn't alter the fact that it should start up with earth to pin 3, no guarantee that it has ever worked and now out of warranty, another thing to try would be battery voltage to make sure up to spec
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Old 20th June 2018, 18:14   #7
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Quote:
Originally Posted by trebor View Post
Hi Steve,

I may have mis read the 1st post as I thought it had been running before but now failing, as you say if new PCB unlikely to be faulty but doesn't alter the fact that it should start up with earth to pin 3, no guarantee that it has ever worked and now out of warranty, another thing to try would be battery voltage to make sure up to spec
The FBH has only been installed this week.
I tried a PCB from a second hand FBH and again the same conditions persist. FBH runs for just over a minute without firing up, then shuts down.


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Old 20th June 2018, 20:12   #8
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Have sent you a pm with my phone number call me might be easier
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Old 20th June 2018, 22:52   #9
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When a FBH receives a start up command, either by 12v to pin 1 or earth to pin 3, basically this is the FBH response.

Start the air fan for full speed check, and short combustion chamber purge, during this period the FBH will.

Start the water pump.
Check flame detector resistance.
Power the glow plug.

Then
Slow the air fan to idle.
Start the dose pump.
Check for combustion chamber ignition
Spin the air fan up to full speed.

If the FBH detects any fault during the start up procedure, the water pump will run, and the air fan will remain at full speed for a pre set time, then the FBH will shut down.

Common faults are the glow plug failing the flame detector resistance check, or PCB common component failure.

12v to the glow plug for a 'if it glows it works' test means nothing. Post ignition the glow plug becomes a flame sensor, if the glow plug resistance is too high matters not if it glows nicely.
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Old 20th June 2018, 22:57   #10
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Quote:
Originally Posted by ROD1 View Post
I tried a PCB from a second hand FBH and again the same conditions persist. FBH runs for just over a minute without firing up, then shuts down.
I would not expect anything less from a used FBH,

I have bench tested more than 50, only 2 of them had a faultless PCB.

Brand new or not, you may have been unlucky to have a PCB or glow plug problem.

Last edited by Devilish; 20th June 2018 at 23:02..
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