Fuel pump and starting issue

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dougie
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Fuel pump and starting issue

Postby dougie » Mon Mar 23, 2020 9:15 pm

I've bought a bit of a project 8v gti pb. (non running due to needing a fuel pump and battery being dead) It was last started in September 2017 by a garage who advised it needed a fuel pump. (I have the paperwork for this) anyway I thought I'll change the cambelt, plugs, leads, oil etc new battery and fuel pump and try to start it. Done all that and turned the key this evening. I can now hear the fuel pump prime when the ignition is on (a lot louder than I remember) but when I turn the key again to fire her up the fuel pump primes again and nothing else happens. No starter motor. It seems to prime for along as I hold the key turned. I don't remember my last one ever priming again on the 2nd turn of the key. Any got any ideas?
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sly_gti
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Re: Fuel pump and starting issue

Postby sly_gti » Mon Mar 23, 2020 10:13 pm

I could be wrong with this, sure I read it somewhere.
Check the light relay is correct way round.

There is a hack the runs the fuel pump continuously on turn of key when relay is upside down
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dougie
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Re: Fuel pump and starting issue

Postby dougie » Mon Mar 23, 2020 10:32 pm

Thanks. I'll have a look 2mos.
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Monkey
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Re: Fuel pump and starting issue

Postby Monkey » Tue Mar 24, 2020 7:52 am

If the starter motor isn't turning, I'd look there first.
Basically, there is a wire, going from the battery, to the ignition switch, back out to the starter solenoid.

If you are getting a click from the engine bay when you turn the key, you are getting power to the solenoid and it's probably either the big wire to the starter, or the motor itself has failed.

If you're not getting a click, have a look at the connections on the starter motor:
You'll have two, one big wire, that will be held on with a 13mm nut, the other is a smaller one, on a connector.
The big is the main power to the motor, the small is the solenoid.

The pump will prime while you're trying, there is a circuit that holds the fuel pump on when the engine is running.
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dougie
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Re: Fuel pump and starting issue

Postby dougie » Tue Mar 24, 2020 9:37 am

Thanks monkey. I will check this later 2day. Got a couple bits to finish at work 1st. I didn't hear any noises other than the fuel pump. So it's normal for the pump to prime / buzz whilst trying to turn over after it's primed on the 1st turn of the key?
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dougie
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Re: Fuel pump and starting issue

Postby dougie » Tue Mar 24, 2020 3:46 pm

I've been out n cleaned up the connecters on the starter motor n it's now turning over. It's does fire n start running for about 3 seconds sometimes (bit rough) but then dies. I stupidly ordered a distributor cap n rotor arm for a EV engine code so I haven't fitted them. PB ones are ordered now. Could this be the issue now? Or should I look at summit else? I have changed oil, oil filter, spark plugs, ignition leads, air filter, fuel pump, cambelt and tensioner but I'm sure it's all lined up. The fuel that's in it is nearly 3 years old n I've put about 15quids worth in with it. Cheers
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Damien.wrl
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Re: Fuel pump and starting issue

Postby Damien.wrl » Tue Mar 24, 2020 4:34 pm

No expert but old fuel is not good, have you checked the fuel filter and heard both fuel pumps working ?
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dougie
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Re: Fuel pump and starting issue

Postby dougie » Tue Mar 24, 2020 5:55 pm

I haven't checked the filter but have bought a new 1. Only thing is I ordered it with the cap and arm which were for an EV engine code. Do you know if the filters are the same across the board? Now I've put new fuel in on top of the old will that make the new stuff bad of just dilute it a bit? I haven't checked the other pump either but I did undo the end of the injector rail and primed it a few times and fuel pumps out. I was told this would get any air out?? How would I check the other pump? Thanks and sorry for the essay!
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T2000
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Re: Fuel pump and starting issue

Postby T2000 » Tue Mar 24, 2020 8:38 pm

Which pump did you change, the lift pump in tank or the one under the car?

In my experience, the lift pump fails first and is easy to change.
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dougie
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Re: Fuel pump and starting issue

Postby dougie » Tue Mar 24, 2020 8:41 pm

I changed the one under the car
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