Technical Fuel pump doesn't prime with key-on: Mk1 Uno Turbo - why?

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Technical Fuel pump doesn't prime with key-on: Mk1 Uno Turbo - why?

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Well as Jai wrote on another post, we had a great time improving the lights on 'Tippex' - Jai's white Mk1 Uno Turbo.

However, I didn't get anywhere with the other problem: the fuel pump doesn't run when you turn the ignition on. It should give a short 'buzz' for a second or two.

The result is that the engine is slow to start - cranks over for several seconds.

I noticed the oil pressure warning light wasn't working. Thinking that may be an 'engine not running' input to the fuel pump relay, I fixed up the connection to the sender so that the light works. Didn't make any difference to the fuel pump.

I then explored the fusebox, checking all add-on fuses and identifying the add-on relays. One particularly interesting, large Lucas relay turned out to be for the (now-defunct) dim-dip system. That's not shown in the wiring diagrams (it's a UK-market variation).

The Haynes manual incorrectly identifies one of the add-on relays as being for the fuel pump. I'm sure this is wrong because I figured out that one add-on relay is the foglights and the other is the high-speed for the radiator fan. Other than the dim-dip and the two relays that are part of the fusebox (heated rear window and horn) there aren't any other relays there.

At about this time the electric windows stopped working - I fought for ages without success, cleaning and fixing connections.

Anyway - the windows started working, and we found that if we operated the windows (key-on, engine off), the fuel pump buzzes...

So - what is likely to be the problem, please? :)


Thanks,
-Alex
 
Don't know if this is relevant to your problem Alex, but I had a similar problem with my Croma Turbo about 10 years ago. It was fitted with Bosch LE2 Jetronic with the tachometric fuel pump relay which I think is the same as the Uno Turbo.

The fuel pump wouldn't self prime when I turned the ignition on. I couldn't trace the problem but noticed that it would prime if I turned the ignition and heated rear window on. I left it like this, using the HRW switch for a few seconds to prime the pump every time I started the car. A few months later I fitted a tow bar to the car and the pump started self priming again. I assumed I must have disturbed (corrected) the rear earthing point in the boot which was common to the fuel pump and my tow bar wiring.

Strange thing was that I got exactly the same problem again about a year later. I went straight for the rear earthing point again but it was OK. On this occasion I found a 'dry' soldered joint on the PCB inside the tachometric relay. Re-soldered that and I never had the problem again.

Dave.
 
From memory the live for the pump is connected via 10amp fuse to pin 87b on the Speedo Relay.

If that helps :D probably not tho.
 
Hi !

Did you solve the problem ?

If yes, could you tell me how, because I've got exactly the same problem...

It seems to be a ground problem, isn't it ?
 
I don't know if the problem on Jai's Uno (in England) is solved yet, but I had a similar (but not the same) problem on my Uno Turbo just the other night.

On mine, the pump didn't prime with the key on AND the engine couldn't run because the pump didn't run when the engine started. The engine ran for a few seconds and stopped.

Faced with a dead car the night before race-day, I was not impressed and began a frantic search. I found a two-pin plug under the dashboard, instrument-side, which had been disconnected during the refitting of the wiring loom. The two wire colours were red and mainly-white (may have had a black stripe, not sure).

I found the matching plug and connected them - and the fuel pump works again.

I still have that strange symptom where the fuel pump primes with the key on when I operate the driver's side electric window (not the passenger's side window). Just like on Jai's Uno! That must be an earthing problem - I haven't solved that one.

-Alex
 
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