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 Post subject: Starting / Fuel problem
PostPosted: Wed Nov 06, 2019 12:50 am 
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Joined: Wed Dec 01, 2010 7:52 pm
Posts: 140
Location: Cartoontown, Oxon
Model: 924 n/a
Hi all, I’ve just bought myself an ‘81 924 N/A after a few years without, and am having a bit of an issue with the car......

It’s happened twice now that after filling up with fuel, the car has refused to start - at all other times it’s absolutely fine - the first time it happened I managed to bump start it, but this morning absolutely nothing worked.

Had the RAC out, and while we got the car to start, we found some anomalies that someone may be able to help with.
1. There’s no Fuel Pump Relay in the No2 relay position - it not just missing the relay, but there’s no socket in that position either!
2. The Fuel pump only receives power when the starter motor engages..... I seem to remember that on my last car (an ‘84), the pump energised on turning the ignition key on, at which point it ran for about 4 secs to prime the system.

We got the car running today by jumping, via the aux fuse box, power from the elective windows, to power up the pump prior to starting, in order to have the correct pressure.

Obviously, I’d like to effect a proper fix for this (there’s already a load of bodges I’ve got to sort on the car, without creating a new one myself), so any thoughts and advice would be gratefully received...

Cheers, Jon


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 Post subject: Re: Starting / Fuel problem
PostPosted: Wed Nov 06, 2019 3:15 am 
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Joined: Wed Sep 08, 2010 8:44 pm
Posts: 9061
Location: Birkenhead (UK)
Model: 924 na
It sounds like the fuel pump relay exists, just not where it should be. Have you pulled the panel forward to check it hasn't just fallen down the back?

If bump starting worked, the fuel pumps must be getting energised so it may indicate that the problem isn't you relay but you may have the hot start problem. There is a bodge to help that by fitting a switch to earth on the cold start valve.

_________________
Andy
1983 Silver(ish)/rust n/a manual - Project Candy, SCRAPPED
1982 Guards Red n/a manual - Project 66, SOLD.
1982 Garnet Red n/a manual - Project XLE (506 licensed, 1421 sorn'd)
1983 White n/a manual - Mr White Returns


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 Post subject: Re: Starting / Fuel problem
PostPosted: Wed Nov 06, 2019 8:06 am 
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Joined: Wed Dec 01, 2010 7:52 pm
Posts: 140
Location: Cartoontown, Oxon
Model: 924 n/a
Thanks DD, the RAC man dropper the fuse box down, so I assume (I know what that makes.... lol) that we’d have seen it.
I’m beginning to wonder if the problem lies with the fuel accumulator...... could the process of refuelling allow pressure to drop from the accumulator, meaning there’s insufficient to allow for starting?

The hot start problem could be it, but the issue has only arisen immediately after refuelling, absolutely fine at all other times, hot or cold.

Can I just check when the pump get energised on other cars - is it when the starter motor engages (like mine), or before that ?

Cheers, Jon


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 Post subject: Re: Starting / Fuel problem
PostPosted: Wed Nov 06, 2019 9:46 am 
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Joined: Sat Jan 30, 2010 11:13 pm
Posts: 15583
Location: Somerset
Model: TheOnly Way Is Turbo
The FPR sometimes triggers on turning the key and sometimes when turning on another electrical item such as lights and/or the starter motor. It does not automatically energise the fuel pump simply by turning the key to on but not cranking.

I sometimes turn the key a few times or switch on something so I hear the fuel pump prime before cranking a cold engine stood for a few days just to get some fuel pressure.

_________________
Steve
1980 924 Turbo Series 1 - Alpine White & Guards Red
Omega forged pistons, lightened and balanced bottom end, ARP studs + Cometic MLS HG, Piper fast road cam, K27/26 3257 hybrid turbo, 951 ducted FMIC, Custom intake manifold, Mittelmotor dizzy & cam pulley, Adj boost - dyno’d at 225bhp @ 1.0bar on previous CGT turbo, Engine datalogged and on boost fuel enrichment managed with Zeitronix ZT2 & Phormula KS4 knock sensor, 944 turbo all alloy radiator, Hayward & Scott custom tapered race exhaust, GAZ Gold coilovers, Fuch'ed up, Quaife LSD
2017 VW Passat Variant GTE Advance - the daily load lugger and mile muncher
2015 Nissan Leaf Tekna - it builds trees when we drive it


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 Post subject: Re: Starting / Fuel problem
PostPosted: Thu Nov 14, 2019 2:02 pm 
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Joined: Wed Feb 13, 2019 11:42 pm
Posts: 65
Model: 924 Lux
bootscooter wrote:
Thanks DD, the RAC man dropper the fuse box down, so I assume (I know what that makes.... lol) that we’d have seen it.
I’m beginning to wonder if the problem lies with the fuel accumulator...... could the process of refuelling allow pressure to drop from the accumulator, meaning there’s insufficient to allow for starting?

The hot start problem could be it, but the issue has only arisen immediately after refuelling, absolutely fine at all other times, hot or cold.

Can I just check when the pump get energised on other cars - is it when the starter motor engages (like mine), or before that ?

Cheers, Jon


I am still chasing the poor hot start problem, not sure if your problem is quite the same but it's all in the same area... I hear a click or "bump" from the (new) fuel pump on turning the ignition key one position but before turning it to actually start which should mean the (new) accumulator is primed, there is also a non-return valve between the pump and accumulator which is part of the chain as it can fail. I have also replaced the relay (in P2 on my '84 car). There is a secondary fuel pump inside the fuel tank, have you check that is ok?

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1984 Lux, alpine white.

In the distant past:
1980 Turbo JFC 212 W, guards red.
1979 Lux EEP 267 V, minerva blue.


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 Post subject: Re: Starting / Fuel problem
PostPosted: Thu Nov 21, 2019 10:01 pm 
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Joined: Wed Dec 01, 2010 7:52 pm
Posts: 140
Location: Cartoontown, Oxon
Model: 924 n/a
Thanks all for your assistance.

Took the car to my local trusted garage and the main culprit was the Fuel Pump Relay that was knackered. I also got them to change the fuel filter as well as plugs and HT leads as there was some dodgy sparking visible.
After week of trouble free local driving I set off on a cold wet Friday night for a weekend in Norfolk but only managed to get as far as Northampton before it stopped combusting and I RAC’d back home.
Investigated on the Monday and eventually found that previous owner had fitted 8A (white) fuses to fuel pump and electric windows- changed these to the correct 16A (red) fuses and now it runs perfectly.


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