Jump to content


Photo

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


  • Please log in to reply
27 replies to this topic

#1 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 20 July 2020 - 05:57 PM

Mini mpi 1997

when motor fires up, it works fine.
When I stop (usually after a hard brake), it doesnt start.

When it wouldnt work, I noticed that the fuel pump wouldn't make a sound, so I changed it.

After a lot of dissappointment, anger and bad mouthng, I feel that there is problem in wiring.
Anyway, today I got my mini working after I moved the wires. I touched the wire that feeds the fuel pump with electricity, and I noticed that it is becoming VERY hot. Is this a proof that there is a shortcirquit somewhere or its a coincidence?


Edited by rolf, 20 July 2020 - 06:03 PM.


#2 DamoMini

DamoMini

    On The Road

  • Noobies
  • PipPip
  • 40 posts
  • Location: California

Posted 20 July 2020 - 06:02 PM

Hot wire indicates that it is pulling too much current which could be indicative of a short, but if it has shorted I am surprised it hasn’t blown a fuse.

I had a similar issue and found that the wire had lost some insulation in the engine bay on its way to the fuse box. In my case, it blew the fuse (repeatedly) before I discovered the fault (note mine is older and is fed directly from the fuse box, maybe yours has a relay?)

#3 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 21 July 2020 - 01:26 PM

Hot wire indicates that it is pulling too much current which could be indicative of a short, but if it has shorted I am surprised it hasn’t blown a fuse.

I had a similar issue and found that the wire had lost some insulation in the engine bay on its way to the fuse box. In my case, it blew the fuse (repeatedly) before I discovered the fault (note mine is older and is fed directly from the fuse box, maybe yours has a relay?)

yes it has a relay.

I thought of the possibility that it could be pulling too much current because of clogged fuel filter, but I saw my papers, it has been changed about 30.000kms before. and after all, it works fine sometimes for days or weeks. And, when I took out the previous fuel pump, everything in the fuel tank and the little mesh filter at the bottom of the fuel pump was crystal clear. So, I am convinced that its not the fuel filter that is problematic.

About blown fuses:
The problems started because a technician took out the fuel tank, and when he put it back, the fuel pump wire was strangled and caused a short and fuses blown. The strangle was corrected and no problem  appeared for a week.After that, the big party started. Works whenever it wants. The little bugger has an angry soul and is sending me on a goose chase



#4 sonscar

sonscar

    Speeding Along Now

  • Members
  • PipPipPipPipPip
  • 442 posts
  • Location: crowle
  • Local Club: none

Posted 21 July 2020 - 04:43 PM

could be the wire is broken inside the insulation increasing its resistance/Steve..



#5 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 21 July 2020 - 07:53 PM

could be the wire is broken inside the insulation increasing its resistance/Steve..

The wire as far as I could touch (20cm) was hot. Thats how it should be if the wire is broken inside the insulation? Or it should be hot only at the broken spot?



#6 sonscar

sonscar

    Speeding Along Now

  • Members
  • PipPipPipPipPip
  • 442 posts
  • Location: crowle
  • Local Club: none

Posted 22 July 2020 - 08:11 AM

Difficult to say,if there are fewer working strands the higher resistance may cause localised heating.You could run a temp wire to bypass the wire,maybe put an ammeter in series to measure the current draw?Steve..

#7 Ado1379

Ado1379

    Super Mini Mad

  • Members
  • PipPipPipPipPipPip
  • 544 posts
  • Location: United Kingdom

Posted 22 July 2020 - 11:48 AM

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.

#8 xrocketengineer

xrocketengineer

    Rocket Man

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,513 posts
  • Location: Florida, USA

Posted 22 July 2020 - 07:45 PM

 

About blown fuses:
The problems started because a technician took out the fuel tank, and when he put it back, the fuel pump wire was strangled and caused a short and fuses blown. The strangle was corrected and no problem  appeared for a week.After that, the big party started. Works whenever it wants. The little bugger has an angry soul and is sending me on a goose chase

 

 

Was the wire section that was "strangled" replaced?  If not, it must be replaced since where it got pinched created a short to ground that blew the fuse but also it might have broken or melted several strands creating higher resistance that heat up the wire. Additionally, the earth wire for the pump is a black wire (of several) connected on the floor between the fuel tank and left tail light. This must be clean and tight or it will cause problems too. 



#9 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 22 July 2020 - 08:13 PM

 

 

About blown fuses:
The problems started because a technician took out the fuel tank, and when he put it back, the fuel pump wire was strangled and caused a short and fuses blown. The strangle was corrected and no problem  appeared for a week.After that, the big party started. Works whenever it wants. The little bugger has an angry soul and is sending me on a goose chase

 

 

Was the wire section that was "strangled" replaced?  If not, it must be replaced since where it got pinched created a short to ground that blew the fuse but also it might have broken or melted several strands creating higher resistance that heat up the wire. Additionally, the earth wire for the pump is a black wire (of several) connected on the floor between the fuel tank and left tail light. This must be clean and tight or it will cause problems too. 

 

Hi xrocketengineer,

 

no the strangled wire was not replaced, just insulated. The heated wire problem appears in the front of the car, in the drivers place next to the the diagnostic plug. The strangled wire was in the fuel tank area, 2 metres away. You think that after two meters it would cause this problem?
Anyway, I found something interesting. I will upload 2 photos of this soon.
About this earth connection between the fuel tank and left tail light: That thing has tortured me in the past, so I cannot forget it...


Edited by rolf, 23 July 2020 - 05:17 AM.


#10 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 22 July 2020 - 08:15 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?



#11 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 22 July 2020 - 09:37 PM

here is the condition of the plug in from of the drivers knees (Left hand drive). The plug is next to the diagnostic plug.

 

 

The red letters are not that visible, so I write them here:

The small text on top says:

"Made 2 mistakes:
1)Connected in parallel

2)Did it AFTER the plug and not before

I just discovered thet the plug connection is burned. See next photo"
 

The lower text at the bottom says:

"Heat starts from here. The wire comes from the front (A) and after the plug (B), goes © to the fuel pump in the fuel tank"

 

Attached File  Fuel pump problem - Parallel connection.jpg   44.67K   0 downloads

 

In the next photo, its visible the burnt connection of the fuel pump wire.
The question is:
This burnt connection is the cause or the symptom?

 

 

Attached File  Fuel pump problem - burned connecton.jpg   47.34K   0 downloads


Edited by rolf, 23 July 2020 - 05:18 AM.


#12 rolf

rolf

    Stage One Kit Fitted

  • Noobies
  • PipPipPip
  • 62 posts
  • Location: Western Macedonia, Greece

Posted 22 July 2020 - 09:52 PM

Difficult to say,if there are fewer working strands the higher resistance may cause localised heating.You could run a temp wire to bypass the wire,maybe put an ammeter in series to measure the current draw?Steve..

Tried to do this, but not bypassing the wire. I did a parallel wiring. And I did it AFTER the burned plug and not before. Probably tomorrow I I will do it before the burned plug to see how it goes.
We are at a good stage I believe!  :-)



#13 Ado1379

Ado1379

    Super Mini Mad

  • Members
  • PipPipPipPipPipPip
  • 544 posts
  • Location: United Kingdom

Posted 23 July 2020 - 09:23 AM


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....

#14 mini13

mini13

    Up Into Fourth

  • Members
  • PipPipPipPipPipPipPipPipPip
  • 3,433 posts

Posted 23 July 2020 - 12:21 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.



#15 xrocketengineer

xrocketengineer

    Rocket Man

  • Members
  • PipPipPipPipPipPipPipPip
  • 1,513 posts
  • Location: Florida, USA

Posted 23 July 2020 - 08:22 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.      


Edited by xrocketengineer, 23 July 2020 - 08:26 PM.





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Mini Spares