Webasto Thermotop 90 Help Please

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Dave100456

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I have a Webasto Thermotop 90 which is 18 months old. Professionally installed but 3000 miles away from the boat’s current location.
Heater is not working and suggestions called for pls.
Symptoms: I have done a reset by turning on then isolating then turning off then switching supply back on.
When I try to start it, the motor “fan” turns the glow plug warms and water flows. However, the diesel pump never clicks and after 7 mins when the “fan” starts to speed up the unit then shuts down. I think there’s a programmed delay in firing up.
The switch for the unit is an illuminated one and it flashes one long and 5 possibly 6 fast times, presume a fault code but what?
Im resaonably technical but there’s little/ no info in the handbook and I’m in a remote location with limited WiFi.
I will respond to suggestions but there’s a 4 hr time difference to UK and internet only when I’m ashore.
Any help gratefully received.
Thanks
Dave
 
Flash codes below so f5 or f5?

Thermo 90S/90ST
F01​
No start-up (after 2 start-up attempts)​
F02​
Flame extinguished​
F03​
Undervoltage or overvoltage​
F04​
Premature flame detection​
F05​
Flame detector interruption or flame detector short-circuit​
F06​
Temperature sensor interruption or temperature sensor short-circuit​
F07​
Metering pump interruption or metering pump short-circuit​
F08​
Fan motor interruption or fan motor short-circuit or incorrect fan motor speed​
F09​
Pencil-type glow plug interruption or pencil-type glow plug short-circuit​
F10​
Overheating​
F11​
Circulating pump interruption or circulation pump short circuit​
 
You say the fuel pump does not "click". My first thought would be check the connections to the pump and then with a multimeter set on say 20v dc check to see if there is voltage. If you use a meter with a needle rather than digital readout you should see the needle move across the scale then drop back quickly and repeat its self.

If the needle moves back and forth a good sign there is the signal to activate the pump but if the pump does not click suggest the pump faulty. Possibly jammed.

If you do not see the needle move back and forth follow the pump wire back to the heater to see that the cable has not been cut or damaged. Check connection at the heater.
 
wiggy said:
If you disconnect fuel line from pump then put 12v across pump and tap wire on and off terminal fuel should flow from pump.
Click to expand...
Please remember before you put an external 12vdc across the pump connections you disconnect the feed wires to the pump from the heater first. If you do not you will damage the ECU in the heater. It will not matter, once you have disconnected the feed wires, the polarity of the external 12v that you connect to the pump. As Wiggy says just tap the wire on and off to simulate the heater ECU.
 
Just got internet.

Thanks for the suggestions will give these a try when back on the boat and get back to the forum with results.

I think the unit should still be under warranty as Caladh suggests but its a long sail from nearest dealer.
 
vyv_cox said:
Be careful with applying 12 volts to the pump. Your advisers may be correct, but if you do this to a Planar you will burn it out, it runs on 7 volts.
Click to expand...
Thanks for that info as I let the fuel level get to low and my Planar 44 stopped working and mostly air in the fuel lines and I was planning to re-prime the system using that method.
 
1581870444504.png
Y is the fuel pump. One side goes direct to the ECU (A2) via socket C pin (2). The other side pin (1) goes via B3 - Temperature limiter on pins 2 and 11 on (A1 circuit) Socket X1. The Vi wire (pin 2)then goes to the main ECU(A2) via contacts on relay K1 and then fuse F3. You say that most of the heater starts up "the motor “fan” turns the glow plug warms and water flows". So I would rule out F3 and K1.

Apart from the other information already given you could have a faulty B3. With the power OFF check to see you have continuity (a short no resistance) between pins 2 and 11. If you have an open circuit that could be your problem. If you have an open circuit and you have the SKILL you could bypass the temperature limiter and see if the pump starts up when you carfully put everything back in place and power up.

The signal to switch the pump on and off to pump the fuel comes via the Mosfet V106.
For more details on the Websto 90 go to their web page Webasto Thermo 90S Manual, Parts List & Troubleshooting
1581870753049.png
 
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Okay, back on land and on-line, I'm 4 hrs behind GMT.

Thanks for all the suggestions and tech info. Looked at the manuals and good to see its a 36month warranty so I don't want to invalidate that by stripping too far.

However, I disconnected pump from the loom and tested with an independent 12v supply - tap, tap and nothing. (should the pump click even if it has no diesel in it?) So can I conclude its the fuel delivery pump which has failed? I have someone coming to the boat from UK and they could bring a replacement pump.

Thanks for all the help especially the links to the technical manuals.

Cheers
Dave
 
yes there should be a 'click per tap'. make sure the pump is ( more or less) upright when you do this as it is a ball bearing that jumps up and down to open then seal the pipe.
If there is no joy then you could try tapping the pump and turning it up and down while doing so to see if you can free the bearing.
If all fails then you can unscrew the top pipe ( careful as the bearing has a spring!) and see if it is gummed up.
I have had hundreds of these pumps through my hands including some absolutely rusty/manky ones and never had a failure!
I may have a webasto pump 'lying around' which I can send to your chum. It will cost you a £30 donation to my Sally Army charity though!
Good luck

oops oops edit required. Just checked back and note this is the 90 series ( 9kw I guess) I dont think my webasto pumps will suit that output. I'll check them out but didn't want to get you excited!
 
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Once you get the pipe off try squirting a little carb cleaner and giving it a good shake. It sounds like it is jammed with sticky fuel.
 
Big John said:
Once you get the pipe off try squirting a little carb cleaner and giving it a good shake. It sounds like it is jammed with sticky fuel.
Click to expand...
Will try this when I get back to the boat. I have a vacuum oil change reservoir if I connect to the pipe at the heater end will this help free it and draw fuel along. The distance from tank to heater is 8+ metres
.
 
Hard to say. As the installation is so young it seems hard to believe the pump has an electrical fault. My gut feeling is that the mechanism inside has siezed. You said previously that you were resaonably technical so I would suggest you very carfully strip the pump down. Do this over a tray covered with a cloth so if any small item should drop out you can easily find it and it wil not roll off the work table. The pump works by a solenoid energised by the 12v and the electrical energy in the form of magnatism operates a plunger inside with two valves (balls) which are sprung loaded. By the reciprical action the plunger and valves move fuel along inside the body of the pump. I would check the plunger is free to move. There should be a very small filter at the input end. Check it is not blocked with crud from the tank. Other wise good luck.
 
Dp42 pump is only on the newer thermo Pro 90. (Not the 90 s or St.) Which runs around 7 volts. The voltage to the fuel pump is regulated by the ecu there is a chance you have damaged the pump by putting it directly to 12 volts.
 
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