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Wire Of Fuel Pump Heats Up - Mini Mpi Sometimes Work, Sometimes Doesn't


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#16 rolf

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Posted 23 July 2020 - 09:44 PM

 

 

If you have a multimeter, do a resistance check from the fuel pump wire to where ever it goes in the fuse box. If it has continuity move the wire around and observe the multimeter.

Good idea!
You mean that I should check the wire in parts, like for example every 20cm?

Check the whole wire first. Put one end on the fuel pump side and one end in the plug that you found burnt. Then wiggle the wire around in as much of the wire as you can get your hands on.


That burning pin is almost certainly a symptom and not a cause. Although I would be very worried at how hot that is getting. I would not drive this until this issue is fixed, as that wire is getting hot enough to potentially melt plastic and cause a fire. And the other end of that wire is almost in the fuel tank....

 

Im not driving this for many reasons.
First is that now its not reliable at all.
Second is that I discovered the heating wire problem, and I dont want bigger damage.
Third is that I am waiting a friend with a thermal camera for android! A unique invention!

 

Anyway, today I tried to clean the connection so I try later to see what is happening.
I discovered that the heat starts from the burned connection and "walks" through the wire. I believe that this is good in comparison to everything else that could be happening.
I was not worried about the hot wire in the fuel tank untl you mentioned it!   :lol: :lol: :lol:



#17 rolf

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Posted 23 July 2020 - 10:08 PM



as you say this started after the tank was removed I wouyld say theres two possible causes,

 

either disturbed debris has gotten into the pump causing it to jam/be restricted and draw more current, or the wire got piched between the tank and body. either way if the p[in has got that hot the wire could be comopromised by loss of insulation, in which case its a fire risk.

 

I would suggest replacing that entire wire, checkign the ones next to it for heat damage, and also check the current loading being drawn.


I examined the visible part of the wire and it is fine, except 1cm in front of the plug that is a bit burned. But, because of what has happened before with the strangled wire, I have already prepared and installed a wire (the one I made a parallel connection). We ll see how it goes and bypass it if needed.



#18 rolf

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Posted 23 July 2020 - 10:14 PM

The way I see it, what probably happened was that the pinched wire shorted to ground and increased the current on the wire to the point of blowing the fuse. Just before the fuse blew the portion of the wiring trace with the highest resistance overheated the most. That turned out to be the pins on the connector. After they got hot, they got oxidised and the resistance at the connection became even higher. After that, just the normal current of the pump motor running was enough to heat up the connector pins and that would made the connection unreliable.

Like mini 13 suggested the wire should be replaced but also the male and female pins on the connector halves that look damaged/oxidised. If you can not replace the pins, cut the wires from the connector halves and use a separate connector for the new wire.      

Thats exactly what I believe that has happened! I tried to take the pin (the female one) out, I didnt manage to do it. It has a kind of security pin that I could not access. Probably I will cut the wire. In the next days I will try a friend's thermal camera to see what is happening


Edited by rolf, 24 July 2020 - 02:51 PM.


#19 rolf

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Posted 24 July 2020 - 07:25 PM

Hi all,

 

I managed to take out the connectors from the plug. Improved the contacts and now it is not becoming hot in 10 seconds as before. Its warming up a bit, like 40 - 45 Celcious (104 to 113 degrees Fahrenheit), even after 5 minutes.

Also, IT SEEMS that there is a tiny rise in temperature at the same wire at the other end where it connects with the fuel pump on the fuel deposit.

 

Any comments?

 

 

 

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#20 xrocketengineer

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Posted 24 July 2020 - 09:56 PM

My main concern would be that the connector pins lost their protective plating when they overheated, therefore they will corrode quicker than healthy pins, when the corrosion comes back, the resistance goes back up and the overheating will occur again on them. Did you check the temperature where the wire was originally pinched?  You might have a similar situation there where the oxidation might accelerate on the wire creating problems later on.   


Edited by xrocketengineer, 25 July 2020 - 01:24 AM.


#21 rolf

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Posted 25 July 2020 - 08:23 AM

My main concern would be that the connector pins lost their protective plating when they overheated, therefore they will corrode quicker than healthy pins, when the corrosion comes back, the resistance goes back up and the overheating will occur again on them. Did you check the temperature where the wire was originally pinched?  You might have a similar situation there where the oxidation might accelerate on the wire creating problems later on.   

I was afraid of this answer to my question...
About "the wire was originally pinched", I have to take out the fuel tank to check.
I prefer to bypass the wire and the pins so I can have my peace of mind... Since the new wire has been installed as a backup before 2 months, bypassing it will be an hour's work. I wanted to avoid cutting the original wire in case its not the real cause, but since I saw that the heating wire has improved, I will do it


Edited by rolf, 25 July 2020 - 08:30 AM.


#22 mini13

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Posted 25 July 2020 - 01:22 PM

temerature is a sign of volt drop, and often once the voltage starts dropping the temp goes up stuff gets hotter etc etc,

I think getting the correct crimp connectors is likly to be an issue, so I would get some crimp bullet connectors, and chop back the wire the other side of the connector a little to remove any over heated wire and leave that conenection external to the multi plug. if you find that your a bit short on cable, you could splice in a fuse to extend, the fuse may be a good idea anyway given the cirrent situation.

 

https://www.12voltpl...use-holder.html

 



#23 rolf

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Posted 25 July 2020 - 08:06 PM

temerature is a sign of volt drop, and often once the voltage starts dropping the temp goes up stuff gets hotter etc etc,

I think getting the correct crimp connectors is likly to be an issue, so I would get some crimp bullet connectors, and chop back the wire the other side of the connector a little to remove any over heated wire and leave that conenection external to the multi plug. if you find that your a bit short on cable, you could splice in a fuse to extend, the fuse may be a good idea anyway given the cirrent situation.

 

https://www.12voltpl...use-holder.html

Thats a clever way to extend a cable!
Making an external connection was my last thought yesterday, but I would include a bypass wire to the fuel pump.


Edited by rolf, 25 July 2020 - 08:55 PM.


#24 rolf

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Posted 25 July 2020 - 08:49 PM

Possibly we have a solution!
My friend with the thermal camera is a mad scientist in electronic cirquits, and insisted that by sandpapering and tightening the hole of the pin connector (which was VERY loose), the problem will disappear. He soldered the pin to make in thicker (!), sandpapered the connector and  everything seems to work fine. Temperature of the wire at the plug reached 37 celsius and at the fuel pump was insignificant . We made a parallel connection, the temperature of the wire (its thicker that the original) went 35 and at the fuel pump was still insignificant. In both cases the fuse went high at 55 celsius which made me a bit sceptical. I tried to open the big scale of the headlights to check on the headlight fuse, its temperature went up to 45-50. I dont know... We will see...

 

Anyway,
 

mini13,

Ado1379,

DamoMini,

mini13,

sonscar,

xrocketengineer

 

thank you all!
Next mission is to find a cheap diagnostic device that is compatible with my mini!
 

 

 

 

 

 

 

 

 

 

 



#25 Alice Dooper

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Posted 27 July 2020 - 09:08 AM

Had the same issue.  Engine started cutting our when we were on along run in the middle of nowhere!!

 

What had happened was that we had changed from the original fuel pump to a mini sport item grafted in.  Old one broke after a pretty vicious landing. 
 

Wires started overheating, especially around the big relay, when the wires and the relay heated up the car died.  We had to stop about 9 times to let it all cool in the 50 miles to home.
 

To repair, we replaced the relay - inspection of it showed heat damage on the fuel pump relay, most likely started when the original fuel pump was killed.

 

the wires and one of the relay plugs had overheated and showed the same kind of damage so they were cut back and a new plug fitted. Wasn’t much give in the wires but thankfully didn’t end up grafting more on.  The quality of the cable Rover used wasn’t great. Heat damage affects the conductive ability of the copper never mind the degradation of the insulator.

 

That was spring 2019 and a few thousand hard miles later we’ve had no issues and the wiring is staying at normal temps.



#26 rolf

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Posted 29 July 2020 - 09:55 PM

Had the same issue.  Engine started cutting our when we were on along run in the middle of nowhere!!

 

What had happened was that we had changed from the original fuel pump to a mini sport item grafted in.  Old one broke after a pretty vicious landing. 
 

Wires started overheating, especially around the big relay, when the wires and the relay heated up the car died.  We had to stop about 9 times to let it all cool in the 50 miles to home.
 

To repair, we replaced the relay - inspection of it showed heat damage on the fuel pump relay, most likely started when the original fuel pump was killed.

 

the wires and one of the relay plugs had overheated and showed the same kind of damage so they were cut back and a new plug fitted. Wasn’t much give in the wires but thankfully didn’t end up grafting more on.  The quality of the cable Rover used wasn’t great. Heat damage affects the conductive ability of the copper never mind the degradation of the insulator.

 

That was spring 2019 and a few thousand hard miles later we’ve had no issues and the wiring is staying at normal temps.

The problem with mine sterted before changing the original fuel pump. Misdiagnosed as broken. It was fine finally, but too late - I hade made modifications to install the new one. And the funny thing was that after changing the pump everything worked for a week or so. The damn connection was playing up. PLayed up many times and all this joke lasted months! Now that electricity flows correct (or just better than the problematic months, acceleration is fine, and sound too.
By saying "fuel pump relay" you mean this?
http://www.minispare...|Back to search

 

 

 

"
 


Edited by rolf, 29 July 2020 - 10:30 PM.


#27 Alice Dooper

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Posted 31 July 2020 - 08:09 PM

 

Had the same issue.  Engine started cutting our when we were on along run in the middle of nowhere!!

 

What had happened was that we had changed from the original fuel pump to a mini sport item grafted in.  Old one broke after a pretty vicious landing. 
 

Wires started overheating, especially around the big relay, when the wires and the relay heated up the car died.  We had to stop about 9 times to let it all cool in the 50 miles to home.
 

To repair, we replaced the relay - inspection of it showed heat damage on the fuel pump relay, most likely started when the original fuel pump was killed.

 

the wires and one of the relay plugs had overheated and showed the same kind of damage so they were cut back and a new plug fitted. Wasn’t much give in the wires but thankfully didn’t end up grafting more on.  The quality of the cable Rover used wasn’t great. Heat damage affects the conductive ability of the copper never mind the degradation of the insulator.

 

That was spring 2019 and a few thousand hard miles later we’ve had no issues and the wiring is staying at normal temps.

The problem with mine sterted before changing the original fuel pump. Misdiagnosed as broken. It was fine finally, but too late - I hade made modifications to install the new one. And the funny thing was that after changing the pump everything worked for a week or so. The damn connection was playing up. PLayed up many times and all this joke lasted months! Now that electricity flows correct (or just better than the problematic months, acceleration is fine, and sound too.
By saying "fuel pump relay" you mean this?
http://www.minispare...|Back to search

 

 

 

 

Yes, thats it.  Shop around as they seem to be a big difference in prices.  Same one was used in a few other Rovers.



#28 Ado1379

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Posted 03 August 2020 - 11:46 AM

You are welcome, looks like we all need a mad scientist every now and then! As for diagnostics.... have you looked a memsdiag or MEMS Rosco? There are lots of other third party apps for androids or windows laptops. These involve making a cable up yourself (plenty of info on this online) but they are handy! I keep an old android phone and the cables in my boot. The whole thing cost about £40 including the cheap and phone




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