2019 4rt has died on me, cut out and would not start

[Rollox]

One more thing: check the ecu plug to make sure that all pins are vertical and not bent. I have already had a machine with starting difficulties and poor engine running and the reason was that the pin for the radiator sensor was crooked and had not made any contact.

[thall1]

I suppose it could be the fan motor drawing excessive current ?

You could either borrow another fan or just park a bike next to yours and wire the slave fan into your loom and see if your bike still dies with the slave fan... obviously your fan won’t be working so don’t run the bike for too long!

[on it]

15 hours ago, thall1 said:

I suppose it could be the fan motor drawing excessive current ?

You could either borrow another fan or just park a bike next to yours and wire the slave fan into your loom and see if your bike still dies with the slave fan... obviously your fan won’t be working so don’t run the bike for too long!

imho why i said  fan drawing excessive current  as  montesa 4rt needs lights to be switched off to start /and a fan relay to cut fan off +3 kicks for starting that tells me there is no spare current in the system  --- as the bike starts cold that says everything is working ! the only thing that then gets added to that system is  the the FAN   as the fan cuts in and out  the fan motor  gets hot ,drawing excessive current to turn until it draws too much current and  cuts the bike out .  Why not the fuel pump drawing to much current ? well the bike would cut out when the fan cuts in for the very first time- ---due to the fuel pump running constantly ,the highest  current pull from the fuel pump is at start up to get the pump to turn thus the need for  lights off and fan relay +the 3 kicks to charge the system fully up .   

[jonnyc21]

14 hours ago, on it said:

imho why i said  fan drawing excessive current  as  montesa 4rt needs lights to be switched off to start /and a fan relay to cut fan off +3 kicks for starting that tells me there is no spare current in the system  --- as the bike starts cold that says everything is working ! the only thing that then gets added to that system is  the the FAN   as the fan cuts in and out  the fan motor  gets hot ,drawing excessive current to turn until it draws too much current and  cuts the bike out .  Why not the fuel pump drawing to much current ? well the bike would cut out when the fan cuts in for the very first time- ---due to the fuel pump running constantly ,the highest  current pull from the fuel pump is at start up to get the pump to turn thus the need for  lights off and fan relay +the 3 kicks to charge the system fully up .   

Good theory... I have never needed more than 1 kick to charge the capacitor/system and 1 to start the bike for any of the Montesa's I have or have ever been on.  (currently have an 07 250 and a 17 300RR) So a low charge output from the system is a possible cause. 

That theory makes me think a bit more about the capacitor making me think it isn't keeping enough of a charge.  The initial fan startup could be putting to much drain on the capacitor and as a capacitor heats up, assuming its on its way out but not dead, they loose some of there ability to work and even stop working completely if they get hot enough in a part way failed state. 

With that, I still vote, check it (preferably when hot) and even consider a replacement even if it seems good. 

Good luck!

Edited August 24, 2020 by jonnyc21

[54tphill]

Ok I’ve spoke to a few people and considered what you guys on here have said, 

I was told that the rpm needs to be 1850 when fan is on. It is. Still coughs, in fact just pulling the bike out the garage this evening and running it again it cut out twice in first 6 minutes

i noticed the Revs started off a bit lower like 1740, is that normal? The revs do go up and down a bit on start up 
 

ive taken the fuel cap breather off 
so that’s ruled out 

I’ve disconnected the landyard as people have said they can be an issue But it cut out and after a few minutes

so that is ruled out

Any other ideas ? 
 

 

Edited August 26, 2020 by 54tphill
Spelling mistake

[jimmyl]

Last simple thing - did you check bank angle removal link? Can’t remember if you said you had ?

 

[54tphill]

1 hour ago, jimmyl said:

Last simple thing - did you check bank angle removal link? Can’t remember if you said you had ?

 

I haven’t no, it had a proper job done on that though when it was removed, inch perfect did it so I’d of thought it’d be fine but I’ll inspect it, 

[thall1]

If it’s ‘coughing’ at the same time as when the fan kicks in then I’d be checking the fan. 
Run the bike up to get it warm, disconnect the fan and run it again, if it doesn’t cough or cut out  with the fan disconnected then try a new fan motor or just borrow one from another bike to double check. 4rt fans come on pretty quick so don’t leave it running too long without a fan connected.


The ‘cheapest’ check would be checking for corrosion in all the connectors and check for good clean earth points..I’d then be looking for corrosion ( and therefore high resistance) in the loom earth wires.

Under the tank, there was on earlier bikes, a yellow connection block with a bundle of earth wires coming to one point so check this. You can prise open the block to get inside to see the earth rail and connectors.
From experience I would also be checking from the capacitor back into the loom for black wire corrosion.. you’ll have to remove the loom and unwrap it to be sure. It looks like a nightmare getting it out but once the tank and Throttle body/ecu is off it doesn’t take too long.
From the capacitor the earth wire extends back into the loom by about 12” then it joins into a ‘crimp’ connector with other loom earths from the rear part of the loom.. These earths then go forward to the yellow block under the tank where earths from the forward part of the loom all come together. You’ll need to get to this lower crimp to be sure that any ‘black wire corrosion’ from the capacitor hasn’t got past this point. Cut back the insulation on the capacitor earth until you find good clean copper, cut off and replace any that’s gone black. If it’s gone past the crimp point then just keep cutting until you get good copper and replace as necessary. Personally I’d solder new wire in rather than add anymore connection blocks. Don’t forget to heat shrink over the joints. If you do have black wire corrosion then I would probably replace the capacitor... from memory the genuine ones aren't that expensive (£40 ish I think) or I expect someone on here will know the values and you could buy from a electrical component supplier. 
There is also a temp sender in the radiator. You could try replacing this...Again I think they are about £25...On non ECU bikes the radiator Temp sender acts like a switch when the rad gets to temp to switch the fan on, however, on the 4rt it sends a signal to the ecu that then switches the fan on via the relay so the relay could be giving a high load?.. again try and borrow a relay to try or just buy one?
After this, if it still coughs and dies I’d be trying to borrow an ECU to try. 

Good luck!

 

[thall1]

Just for your info , mine used to cough every now and again .. eventually it stopped and no amount of kicking would get it to start. It would start if I disconnected the fuel line to the injector and manually fed the injector but it would run very rich as if ‘choke’ was on.. hence why I later replaced the temp sensor.

i got the ecu ‘read’ and it said there was a temp fault... so despite already fitting a new temp sender I fitted another from a good bike... still wouldn’t start or if it did it took 20-30 kicks and wouldn’t keep running. A loom was fitted from a donor bike and we thought that had fixed it but 24 hrs later the bike once again refused to start... ecu was swapped again (this had already been done a few times previously) and that sorted it.. I bought the 2nd ecu that was fitted and the donor bike had a programmable ecu fitted at a later date. 

[54tphill]

2 hours ago, thall1 said:

Just for your info , mine used to cough every now and again .. eventually it stopped and no amount of kicking would get it to start. It would start if I disconnected the fuel line to the injector and manually fed the injector but it would run very rich as if ‘choke’ was on.. hence why I later replaced the temp sensor.

i got the ecu ‘read’ and it said there was a temp fault... so despite already fitting a new temp sender I fitted another from a good bike... still wouldn’t start or if it did it took 20-30 kicks and wouldn’t keep running. A loom was fitted from a donor bike and we thought that had fixed it but 24 hrs later the bike once again refused to start... ecu was swapped again (this had already been done a few times previously) and that sorted it.. I bought the 2nd ecu that was fitted and the donor bike had a programmable ecu fitted at a later date. 

It does make me think I should swap my ECU, how old was your bike at the time, mines 20months old! How much was the ECU to buy? I assume it’s an easy plug in job I could do myself ? 

[thall1]

Mine was a 2006/7 bike but I have heard of newer bikes with ecu faults .. I think a new ecu is around £400... I think I paid about £250 for the one that was fitted on mine to test. The ecu is part of the throttle body. It’s all a bit tight but it does come out. 

[thall1]

I think you need to try and borrow one first.. it’s a lot to pay out for if it’s not the issue. If the bike came from a dealer have a chat with them and see if they can help?

[jonnyc21]

With how quick you seem to see the issue an ECU swap/test should provide a lot of good information... If it still happens try swapping other parts, the capacitor, the throttle body, the injector... really could be a number of things at this point... good luck.  

[thall1]

I did try all the swapping all the above parts when mine played up, fuel tank, injector, ecu, loom, temp sensor and a few times over but chasing an intermittent fault is tricky... 

[jonnyc21]

35 minutes ago, thall1 said:

I did try all the swapping all the above parts when mine played up, fuel tank, injector, ecu, loom, temp sensor and a few times over but chasing an intermittent fault is tricky... 

Sorry if there was any confusion, my comment was intended for 54tphill as he indicated his issue shows up inside 6 min or so.