Webasto 3500 air - advise please?

[solar]

After a week of constant day & night work turned heat off for a few hours and since then I can't turn it on again?

I'm getting a signal of 2 slow flashes followed by 5 fast ones. What's that?

Fuel pump ticking well for 1-2 minutes when trying to ignite and then stops...even after a few knocks on the pump.
Fuel tank is 3/4 full.
On shore power and fully charged batts.

Any ideas how to make it work again?
Thank you.

 

[SimbaDog]

"Self-Diagnostic System (Reading Flash Codes)
A flash code will be generated on the indicator light of the control element. These flash codes indicate a
malfunction and subsequent operational interruption. There are up to ten codes available depending on
the nature of the malfunction and the heater model (see Table 2).
In order to make a correct analysis, it is necessary to understand the flash code event. The flash code
pertains to the control element (switch) only. The flash code is only visible during the after-run (cooldown)
period of operation (an optional timer will hold the last code in memory until corrected, see “F”
codes in parentheses on Table 2).

During the flash code event, you will see five quick flashes followed by a slower sequence of flashes from
one flash up to ten flashes. The slower sequence of flashes is the actual malfunction code. The five quick
flashes are only an indication that a malfunction has been detected and that the code will be displayed.
Count only the slower sequence of flashes to obtain the current malfunction code.
For example ( = one flash):
Event code 4X (F 04): ... ... ... ...
The fast/slow sequence will be repeated until the heater completes the after-run (cool-down) cycle after
which, the code will be stored in the control unit memory.

No Function Electrical wiring, fuses
Control unit
Fuses, battery connections
Power at red wire, ground at brown wire
Control unit malfunction

1X Flash (F 01)
No start after 2 start
attempts No flame-up
Fuel system
Combustion air
Burner
Fuel level - No fuel - Fuel system not primed
Type of fuel being used
Plugged fuel filter - replace
Fuel line connections and clamps loose
Air intake or exhaust - restricted or plugged
Clean or replace burner unit

2X Flashes (F 02)
Flame-out during
operation
Fuel supply (shortage)
Burner
Restriction in fuel system
Plugged fuel filter - replace
Fuel line connections and clamps loose
Type of fuel being used
Clean or replace burner unit

3X Flashes (F 03)
Low or over voltage for
more than 20 seconds
Electrical system Load test batteries
Corrosion at connections
Loose connections

4X Flashes (F 04)
Premature flame
detection
Defective flame sensor
Defective flame sensor/
glow pin
Replace flame sensor - Air Top 2000 S only
Replace flame sensor/glow pin - Air Top 3500/5000
only

5X Flashes (F 05)
(Air Top 2000 S Only)
Flame sensor
Wiring
Defective flame sensor
Damaged or corroded wiring, open or short circuit
Replace flame sensor

6X Flashes (F 06)
Temperature sensor
Wiring
Defective temp. sensor
Damaged or corroded wiring, open or short circuit
Replace temperature sensor

7X Flashes (F 07)
Fuel metering pump
Wiring
Defective fuel pump
Damaged or corroded wiring, open or short circuit
Replace fuel pump

8X Flashes (F 08)
Combustion air fan
Wiring
Wrong RPM
Defective fan motor
Damaged or corroded wiring, open or short circuit
Replace combustion air fan
Replace combustion air fan

9X Flashes (F 09)
Glow pin
(Ceramic igniter)
Wiring
Defective glow pin
Defective flame sensor/
glow pin
Damaged or corroded wiring, open or short circuit
Replace glow pin - Air Top 2000 S only
Replace flame sensor/glow pin - Air Top 3500/5000
only

10X Flashes (F 10)
Overheating
Overheating
Air flow
Wiring
Defective temp. limiter
Switch heater off and back on (see air flow)
Motor/fan obstruction, heating air flow blocked
Damaged or corroded wiring, open or short circuit
Replace temperature limiter

11X Flashes (F 11)
(Air Top 3500/5000 Only)
Temperature limiter
Wiring
Defective temp. limiter
Damaged or corroded wiring, open or short circuit
Replace temperature limiter

12X Flashes (F 12)
(Air Top 3500/5000 Only)
Control element
Wiring
Defective control element
Damaged or corroded wiring, open or short circuit
Replace control element

 

[solar]

Thanks,great info.
Could it be that I'm too low on fuel for the Webasto to operate with 3/4 boat main tank?

 

[SimbaDog]

I wouldn't have thought so unless the tank outlet is at that level
Can you trace the fuel line back to the tank to check?
Is there by any chance a filter in the line that has become blocked?

 

[solar]

Will have a look in the morning it"s too dark & cold now...also will top up the tank who knows?
Will post after.
Thanks again.

 

[Stork_III]

I had similar heater action, replacing blocked filter in fuel line cured it.

 

[tjc]

Had the same - had the dealer clean the burner and it's fine now. Mine had 400 plus hours use in one year which, apparently, is heavy use for a boat. That coupled with the sporadic nature of the heaters use caused the burner to coke up a bit.

 

[Steve Clayton]

The flashing 5 just indicates that the unit has identified a problem and is closing down.

The flashing 2 is the key - in this case there is a fuel (lack of) problem.

You say there is plenty of fuel; in my case if fuel runs low then I have to add at least 20 litres of fuel to deliver a head of fuel for the Webasto to strike and it can then take up to 5 start attempts for it to work.

There should be an inline fuel filter just before the pump; it's sealed and you cant take it apart; if it's blocked then I've found that an inline filter for about £3 (as opposed to £18 for a Webbie part) from Halfords works just as well (at least for the last 2 years).

I'm also told in good faith that there is a thimble type filter in the inlet to the fuel pump; the manuals don't make any reference to this. In order to get it out; using a small screwdriver destroys it and so you need to have a spare to hand; not had to go this far yet!!!

If you want PDF's of the fault card and the installation/maintenanace guides for this model of Webbie PM me your email address

 

[solar]

Thanks guys,
Tomorrow will be at the boat and will start with adding fuel to the tank.
If not, I'll look at the filter and after that it's burner cleaning...and we'll see.
BTW ,how do I open the heater's case to find that #$%^ burner? anyone have any pic's?
Will post results later.

 

[solar]

O.K...
Added 20 liters of fuel,tank is full now...turned on heater = NO heat.
Took off filter,looks clean but took it off anyway and connected fuel line directly to pump = No heat.
Fuel is getting to the pump but no ignition at the inside of the unit.
The pump is pulsing for a few min and then stops due to system shut down after a few attempts to ignite.
Tried to start it 5 times...same results = nada.2 slow flashes & 5 fast ones as before...

Need advise where to go from here...
How the unit case is getting opened?see no bolts...
Where is the burner inside?any glow plug to mess with?
Is it a DIY job or I better call a Webasto wizard?
GRRRRRRRRRRR...

 

[steve6367]

During the week of constant use was the heater running on a low heat setting? If so did you give it a blast on full before switching off?

The burner can coke up easily if left running on one of the lower heat outputs for extended periods.

Steve

 

[snooks]

Phone Keto Marine: +44 (0) 1202 690900

They are everything Webasto

 

[jellyellie]

I've never opened up a Webasto before but am somewhat over-familiar with Eberspachers after I had a similar problem with mine in December. After checking pretty much every component, we finally traced it to six tiny weeny holes in the fuel spinner that were coked up. One needle later, they were clear and the Eberspacher fired up fine. I'm not sure if Webastos have the same design - I presume it must be vaguely similar - but hopefully it's a pointer nonetheless.

And you're lucky to have diagnostic lights, that's just cheating!!

 

[Steve Clayton]

looks serious:

Here you go:
905
9.2.6 Glow Plug / Flame Sensor, Replacement
9.2.6.1 Removal
1. Remove housing components / covers (see 9.2.1).
2. Remove insulation mat (15, Fig. 902).
3. Remove control unit (see 9.2.4.1).
4. Remove combustion and heating air fan (see 9.2.5.1).
NOTE
Perform steps 5 through 10 for a burner (19) without
shield. Steps 11 through 14 refer to an installed burner
with shield (18).
5. Loosen (lever off) fastening clamp (20) of burner (19).
6. Push grommet of glow plug / flame sensor (11) out of
housing of heat exchanger (14).
7. If required carefully bend up fastening clip for cable
of glow plug / flame sensor (11) located on burner
tube (12).
8. Withdraw burner (19).
9. Remove oval head screw (9).
10. Withdraw glow plug / flame sensor (11) from burner
(19) and remove.
11. Remove EJOT FDS screws SF (10).
12. Push grommet of glow plug / flame sensor (11) out of
housing of heat exchanger (14) and withdraw burner
with shield (18) from burner tube (12).
13. Remove oval head screw (9).
14. Withdraw glow plug / flame sensor (11) from burner
with shield (18) and remove.
15. Perform procedures on components after
disassembly (refer to 9.1.1).
9.2.6.2 Installation
NOTE
Steps 1 through 5 to be performed for a burner
(19, Fig. 902) without shield. Steps 6 through 13 refer to
an installed burner with shield (18).
1. Insert glow plug / flame sensor (11) into burner (19)
(cable in direction of opening for cable grommet) and
secure with oval head screw (9).
2. Tighten oval head screw with 0.8 ± 0.08 Nm.
3. Locate burner for installation and press grommet of
glow plug / flame sensor (11) into housing of heat
exchanger (14). Bend down fastening clip as required.
4. Route cable of glow plug / flame sensor (11) below
fastening clip and through opening in housing of heat
exchanger (14).
5. Secure burner (19) in position using fastening
clamp (20).
6. Insert glow plug / flame sensor (11) in burner with
shield (18) (cable routed towards opening for
cable grommet in shield) and fasten with oval head
screw (9).
7. Feed cable of glow plug / flame sensor (11) through
opening in shield.
8. Torque oval head screw (9) to 0.8 ± 0.08 Nm.
9. Hold burner with shield (18) upside down, engage
burner tube (12) and rotate to assemble with
combustion tube.
10. Push grommet of fuel supply into housing of heat
exchanger (14).
11. Fasten shield and combustion tube (12) with EJOT
FDS screws SF (10).
12. Torque EJOT FDS screws SF (10) to 2.5 ± 0.25 Nm.
13. Feed cable of glow plug / flame sensor (11) through
heat exchanger and plug grommet.
14. Install combustion and heating air fan (see 9.2.5.2).
15. Install control unit (see 9.2.4.2).
16. Fit insulation collar (15).
17. Refit housing components / covers.

 

[solar]

looks serious:

Here you go:
905
9.2.6 Glow Plug / Flame Sensor, Replacement
9.2.6.1 Removal
1. Remove housing components / covers (see 9.2.1).
2. Remove insulation mat (15, Fig. 902).
3. Remove control unit (see 9.2.4.1).
4. Remove combustion and heating air fan (see 9.2.5.1).
NOTE
Perform steps 5 through 10 for a burner (19) without
shield. Steps 11 through 14 refer to an installed burner
with shield (18).
5. Loosen (lever off) fastening clamp (20) of burner (19).
6. Push grommet of glow plug / flame sensor (11) out of
housing of heat exchanger (14).
7. If required carefully bend up fastening clip for cable
of glow plug / flame sensor (11) located on burner
tube (12).
8. Withdraw burner (19).
9. Remove oval head screw (9).
10. Withdraw glow plug / flame sensor (11) from burner
(19) and remove.
11. Remove EJOT FDS screws SF (10).
12. Push grommet of glow plug / flame sensor (11) out of
housing of heat exchanger (14) and withdraw burner
with shield (18) from burner tube (12).
13. Remove oval head screw (9).
14. Withdraw glow plug / flame sensor (11) from burner
with shield (18) and remove.
15. Perform procedures on components after
disassembly (refer to 9.1.1).
9.2.6.2 Installation
NOTE
Steps 1 through 5 to be performed for a burner
(19, Fig. 902) without shield. Steps 6 through 13 refer to
an installed burner with shield (18).
1. Insert glow plug / flame sensor (11) into burner (19)
(cable in direction of opening for cable grommet) and
secure with oval head screw (9).
2. Tighten oval head screw with 0.8 ± 0.08 Nm.
3. Locate burner for installation and press grommet of
glow plug / flame sensor (11) into housing of heat
exchanger (14). Bend down fastening clip as required.
4. Route cable of glow plug / flame sensor (11) below
fastening clip and through opening in housing of heat
exchanger (14).
5. Secure burner (19) in position using fastening
clamp (20).
6. Insert glow plug / flame sensor (11) in burner with
shield (18) (cable routed towards opening for
cable grommet in shield) and fasten with oval head
screw (9).
7. Feed cable of glow plug / flame sensor (11) through
opening in shield.
8. Torque oval head screw (9) to 0.8 ± 0.08 Nm.
9. Hold burner with shield (18) upside down, engage
burner tube (12) and rotate to assemble with
combustion tube.
10. Push grommet of fuel supply into housing of heat
exchanger (14).
11. Fasten shield and combustion tube (12) with EJOT
FDS screws SF (10).
12. Torque EJOT FDS screws SF (10) to 2.5 ± 0.25 Nm.
13. Feed cable of glow plug / flame sensor (11) through
heat exchanger and plug grommet.
14. Install combustion and heating air fan (see 9.2.5.2).
15. Install control unit (see 9.2.4.2).
16. Fit insulation collar (15).
17. Refit housing components / covers.

Thanks,now if you only could add the pic's...without them I'm afraid I"m a bit lost...

 

[jonoR]

Is there enough charge in the battery to fire it up ?

 

[Steve Clayton]

Is there enough charge in the battery to fire it up ?

Good point but this doesn't appear to be the issue. If the unit senses either under- or over-voltage then it would crash out flashing fast 5 then 3. It goes past the voltage test sequence and subsequently flashing 2; which means it's had 5 background attempts to fire up with flame failures. It is likely that fuel ain't getting to the burner with manual advising the problem:

Fuel supply (shortage)
Burner
Restriction in fuel system
Plugged fuel filter - replace
Fuel line connections and clamps loose
Type of fuel being used
Clean or replace burner unit

The standard fuel filter is a small sealed canister which you can't fix, or unblock and this could be the root cause. I had this problem and fitted a see-through filter so at least I can validate that fuel is being pushed through the system

As said before I'm told there is also a small thimble filter on the inlet side of the pump (which I can't find any reference to in the fitting/maintenance manual) which could also be the problem.

As the fuel pump is ticking then easiest to check the filters first before taking the unit apart.

Replace the primary filter with one you can see through; it will take a while for the pump to pull the fuel through and the unit may/will crash out whilst it's re-priming the system. If you steadily see the fuel filter filling then it looks like the pump is OK but the secondary filter might still be an issue with fuel delivery to the unit slowed.

If the pump is ticking with no fuel being sucked into the filter then it's likely to be a pump issue.

One last thought; there might be a filter on the end of the fuel draw-off pipe? - could be blocked?

 

[omega2]

I agree, low voltage on the battery, will prevent it starting up, at least that is what happens to our Propex heater.

 

[solar]

As said I'm on shore power & the batts are full.

Still need tips how to open the Webasto unit case and find the burner from those who ever did that.
Can't see any bolts on the case cover???

Thank you.

 

[Stork_III]

As said I'm on shore power & the batts are full.

Still need tips how to open the Webasto unit case and find the burner from those who ever did that.
Can't see any bolts on the case cover???

Thank you.

The case snaps together, press the sides to open. I have exploded parts diagram PDF send PM to me with your email and I will send it.,