15 replies to this topic

[elguapo]

Hi all

 

chasing down an intermittent fault on a 1994 SPi.

 

I have changed the relay pack for a new one as the old one finally had corroded away, unfortunately whilst this now engages the stepper motor and everything correctly I am still getting no start for the fuel pump.

 

Before I do any more costly changes such as the ECU I figure it is more than likely a faulty earth. The inertia switch appears ok.

 

I know a simple test will be to wire a new/temp earth to the fuel pump and check the circuit but the question is where does the fuel pump originally get earthed to as I would like to retain the circuit incase it is used for other systems.

 

Does the wire go back to the engine bay?

 

thanks

 

Mike

[xrocketengineer]

All the earth connections are located by the left tail light next to the fuel tank. That includes the pump, gauge sending unit, alarm boot switch and all rear lights.

[100ev8]

now i got a strange idea the pump earth is on the right rear light. seem to remember trying to start one without the o/s/r light in with no joy till the right was earthed

i know the n/s makes more logic .but check o/s

[elguapo]

cheers! Will take a look tomorrow if I am sober enough!!

[xrocketengineer]

now i got a strange idea the pump earth is on the right rear light. seem to remember trying to start one without the o/s/r light in with no joy till the right was earthed

i know the n/s makes more logic .but check o/s

It is possible. The factory manuals only show an earth connection on the right side for the Cabriolet with no detail for the SPI saloon. The pre SPI manual show the earth on the left side only and the MPI manuals show the earth on the left too.

[elguapo]

The problem seems to be the lack of documentation for the SPi's as even part life cycle things changed.

 

Just so I know I am looking at the right thing!! The fuel pump is the bit that's in the tank facing in towards the boot near the bottom quarter of the tank and not the bit at the very top that's almost impossible to reach?

[FlyingScot]

The problem seems to be the lack of documentation for the SPi's as even part life cycle things changed.
 
Just so I know I am looking at the right thing!! The fuel pump is the bit that's in the tank facing in towards the boot near the bottom quarter of the tank and not the bit at the very top that's almost impossible to reach?

No that's the fuel level sender, the pump is the bit at the top

See here http://www.minispare...s.aspx?2~18~176

FS

Edited by FlyingScot, 18 December 2013 - 06:30 PM.

[elguapo]

thanks! so its the pain in the arse bit to get to then ;)

[FlyingScot]

Yup sorry about that

FS

Edited by FlyingScot, 18 December 2013 - 08:22 PM.

[elguapo]

Well the earth is good! the weird thing is we see power to the pump but it does nothing, we get around 3 volts that quickly drop off. We have hard wired the pump and it starts and car runs fine.

 

The question is, could this be an imobilisor or other issue? The car does appear to have some sort of black box behind the dash that looks like a rover module of some kind but I never had any fobs and the car has always started. Off to an auto electrician now so fingers crossed its a simple fix. I'd be happy to actually put my own little switch circuit at the front so I can forget about all the other components!!

[FlyingScot]

Sounds like bad connection wiring. The pump should run for a few seconds to pressurise the line, but would be more than 3V.

Anyway an auto sparks should be able to chase this down for you.

FS

[elguapo]

aye so left it with them. Give me a carburettor any day!!!

[xrocketengineer]

It is probably that the wire from the relay to the pump has developed high internal resistance due to corrosion, it is about to break or a bad connection somewhere. I had the same situation with the radiator electric fan. It would not run. If I disconnected the connector from the fan motor and checked for voltage, I had 12VDC. But if the connector was connected the voltage would drop to 0VDC. The fan would run fine if hot wired or if the relay was directly fed from a 12VDC source. So I ended up having to replace a section of wire from the fuse to the feed for the relay. 

[100ev8]

check the power at the multi plug on the left behind the dash and see what power is there to the pump

[elguapo]

do you mean the plug that connects to the wiring loom for the rear of the car?