Electric fuel pump wiring (Novice alert!)

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bigherb
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

Yes if you have eliminated all the power feeds then only leaves the relay
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

Cheers for all your help dude, new relay ordered so fingers crossed!
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

New relay arrived today (the one linked to earlier in this thread it's got a different pin layout so I've had to prise the spade connectors out of the relay socket to connect the cables to the terminals on the new relay. All connected up, but still no joy.

On turning the ignition to the first point the fuel pump runs for maybe 3 seconds then stops, then when turning the engine over the fuel pump doesn't run and the engine won't start.

I'm not sure where to go from here ;o(
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bigherb
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

Has it got an ignition spark?
It needs a trigger signal from terminal 1 of the coil.
Which would have been this test. "If you have a 12v test lamp probe it into the 31b terminal of the relay socket the light should pulse on and off when you crank the engine".
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

Okey doke, I thought I'd ruled that out with the multimeter, I'll try and get hold of a test lamp tomorrow unless can I use a domestic screwdriver lamp tester?
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

bigherb wrote:Has it got an ignition spark?
It needs a trigger signal from terminal 1 of the coil.
Which would have been this test. "If you have a 12v test lamp probe it into the 31b terminal of the relay socket the light should pulse on and off when you crank the engine".

Right just back in from testing with a test lamp. when cranking the engine the light is on constantly rather than pulsing.

Does that indicate a faulty coil or something a lot more expensive?

Cheers,

Ben
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bigherb
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

ben50 wrote:
bigherb wrote:
Right just back in from testing with a test lamp. when cranking the engine the light is on constantly rather than pulsing.

That's your problem
Was the engine running before you fitted the pump?
Did you remove any wires from the coil are they all back in place?
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

Hi, yeah the engine was running before fitting the pump - well until the mechanical fuel pump gave up the ghost and left us on the side of the M5!
I've not taken any of the wire off the coil except to plug one into the back of a piggyback connector on the terminal 1
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

have you got a picture of the coil connections?
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

here you go:

Image

Image

Image

Image

Image

Image
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

There should only be two wires to terminal one on the coil the green one to the ignition amplifier and one to 31b of the relay. Where does the other one go?
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

That one connects to a rev counter
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

I can only see three wires to terminal 15.
You should have one from the connector box behind the coil. one to the ignition amplifier, one to the carbs (all black) and the red one to 15 on the relay.
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ben50
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Re: Electric fuel pump wiring (Novice alert!)

Post by ben50 »

I don't have a connection to the carbs, it's got dellortos which don't seem to have any electrical terminals - the dellortos were fitted about 2 months ago (by a garage) and it's all been fine until now - although the RAC chap that attended thought the new carbs may have put extra strain on the mechanical fuel pump and added to its failure?
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Re: Electric fuel pump wiring (Novice alert!)

Post by bigherb »

Has it still got the electronic ignition or has that been changed as well?
If it has. Check the brown earth wire from the ignition amplifier is connected to a good earth. It looks like the idling stabiliser has been removed are the two plugs connected together properly?
Otherwise check the ignition system remove the centre HT lead from the distributor and wedge the end about 6mm away from a metal part of the engine (not the carbs) remove the three pin plug from the distributor and insert a paper clip or something in the centre terminal. Turn the ignition on then scrap the paper clip along a metal part of the engine you should get spark from the HT lead. If you do get a spark then it is a distributor fault. No spark then it is an ignition amplifier/wiring fault.
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