Rover V8 fuel pump feed

She is running, turned out to be the fuel pump was not running and nothing to do with the tappets or a flooded engine!

It threw me as the fuel pump never used to run on the ignition switch anyway, but obviously ran when the engine was running (engine/exhaust too noisy to hear it!).

I connected the pump directly to the battery and she started and ran like a dream!

I have a question, anyone know how the pump is connected normally?

As I say it's not connected to an ignition feed as it didn't used to run with the ignition on; only when the engine itself was running and I presume during cranking. I can't find a feed which is only live when the engine is running and not live with just the ignition on. I've checked all the fuses and they are fine, although none are specifically marked as fuel pump.

The car looks reasonably well wired (although it's a Rover V8 into a TR7 so could be anything!) how would you guys wire it in?

I am tempted to wire it to ignition but there isn't a return feed for fuel back to the tank, at least not from the carbs themselves (twin SU's) you can hear the pump struggle when the pressure builds up if I don't start it. Can you flood SU's like this?

At the moment I have installed a single wire from the battery to the pump to get me to the MOT on Saturday. I assume it will fail on that? If that's the only thing I will be a happy man!

Keep well all,

Will

Reply to
Will Reeve
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I think you will find the fuel pump is switched via the oil pressure switch.

Regards, Graham L

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Reply to
Graham

That'll do it :->

I can't recall which fuse is normally used. However, mine has been wired in to a switch that is powered from the Accessory position on the ignition switch, so my wiring is also non-standard.

Dunno about SU's per se, (mine has a Holley on it :-)[1], but it starts better if you allow the system to pressurise, wait a couple of seconds (regular tick-tick-tick from the pump) and then start with a pump on the gas. It's fine in the time it takes me to fit the fascia of the radio.

[1]Showing off, it's hidden under the pancake at
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Cheers,
Reply to
James Dore

On the injection ones it runs when cranking, and then a switch inside the AFM takes over.

On carb ones it runs when cranking and then on a feed from the oil pressure switch.

Reply to
Dave Plowman (News)

The fuel pump only pumps when the engine is cranked or there is oil pressure, I think the oil pressure switch is on the offside of the engine and it has a three wire plug running to it, if you bridge the two terminals [1] that are furthest apart you should hear the pump work and the engine will start. You either have no oil pressure or the switch ( common fault ) is trucked.

[1] The last time is did this was about 15yrs and many Lagers ago, so I am not completely sure about which two wires you bridge!
Reply to
Mill Autos

Thanks Graham, Dave and everyone else, you have got me a little worried about oil pressure now, but as the car was running in the garage for about 20 minutes yesterday I think it would have seized by now !-) The light on the dash goes out so I guess there is a relay fitted or maybe it's a simple wiring problem.

I'll have a look under her at MOT time. I can see at least one spade connector join in the wire run to the fuel pump under the car!

There is also a mystery toggle switch under the instrument binnacle, it's sole purpose as far as I can see is to extinguish the oil pressure light!!!!!! With the ignition on (engine not running) the oil pressure light is correctly on, flick this switch and it's off! I have always left it in the "on" position and the engine oil pressure switch seems to switch it off OK. It doesn't effect the running of the engine at all and doesn't switch the fuel pump on/off so I am at a loss to it's purpose!

All a little strange, but to break a habit of a lifetime, I worked on the "if it's not broken don't fix it" approach and left it alone. I don't think this switch is a standard fit but it looks a period early 1980's item, nice and solid! I had forgotten about it until you mentioned oil pressure.

I'll get her through the MOT first and get to the bottom of it on Sunday. I now know where to look, first stop the oil pressure switch and buzz some wires out back to the fuel pump.

I will thinking of seller her next year (only managed 1k miles this year) but starting her and watching the engine rev and rock side to side and the exhaust note usually puts it off another 6 months :-)

Keep well,

Will

Graham wrote:

Reply to
Will Reeve

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