Hi All,

Bit of background info here... I have a MY 1999 which has a Link G3 Ecu. Driving along the other day and the car just died. would turn over but wouldnt fire up. Then I realised I couldnt hear the fuel pump priming as it used to. I always had to wait for the fuel pump to fully prime before starting it. so I checked and there was no power getting to the fuel pump. since then I have followed guides and fed a constant power feed to the fuel pump and yes when you turn the ignition on you can hear the pump pumping etc... but sometimes it wont start, and it seems the same as if I tried starting it before the pump was primed before all the issues, but sometimes it is perfectly fine.just wondering if anyone has any ideas? dont claim to understand the fuel system fully.

 

 

Thanks mate, appreciate the reply, although a fuse would make me wonder why it sometimes did and didn't start

 

Are you saying it's failing to start despite a permanent feed to the fuel pump? If you've removed the permanent feed and now it intermittently fails to start it could be the fuel pump relay, mine did this and a new relay sorted it, you can swap the one from the heater fan as they're the same, both are up behind the fuse box on the drivers side, it's probably easier to remove the lower dash panel to get to them. Alternatively it could be relay contacts in the immobiliser, bit more difficult to resolve but worth re soldering all the pins on the relays before you rip it out.

Shane

 

Hi Shane,

Nope... It always started fine on a standard setup as long as I let the pump prime first. Then something died and there was no power to the fuel pump so I hard wired it. Since hardwiring I can hear the fuel pump working and hear what I imagine is fuel whooshing around under the bonnet around the fuel rail etc... But sometimes it won't start despite cranking over fine.

 

If it's still on the original 19 year old fuel pump I would be looking to replace that,if it's not that old I'd check wiring,but as you have a direct live feed and it's still failing then my money's on an old worn pump.

 

Tried 2 X new fuel pumps...

 

soon lost mi money there then!
You got a data cable with your link g3?

 

Haha yup... So did I buying fuel pumps lol.
Yeah got a USB cable that connects to the G3 but no laptop to connect it to. Why's that?

 

You could do some data logging to help look for a fault?
When it 'sometimes doesn't start' is it from cold or always when warmed up?
When you fitted the new pump/s did you try wiring back as Standard or keep the direct feed?
Checked for any fuel leaks?
Guessing you've replaced fuel filter?
Next check would be fpr or the pipe running to it for splits.

 

Definitely seems a lot worse from cold, first thing in the morning etc. Can't find any leaks anywhere but will take another look. Also not replace fuel filter.

 

Just check the vacuum pipe to fpr while you're in there.
Can be a pita finding a fault like this!

 

You say you've bought 2 pumps but not which brand / model.
Having been through a similar escapade and spending weeks swapping bits over on my car to no avail I finally identified a crap fuel pump - a 290lph one from a "bad batch" which the supplier immediately admitted to when I rang them. Until this point my car had been pulling timing at around 410bhp and kept losing power.
I remember me and Simon (late JGM bless him) pulling our hair out over it.

A mate with the same pump had the same issue so if you've bought from the same supplier and it's cheap I'd suggest putting your pump in another car and testing it, and if it fails / cuts out as obviously as you say I'd be straight on the phone to the supplier.
Unsurprisingly I opted for a refund and instead went for an RCM alternate which was fine after that and the car went on to make 440bhp.

 

 

Ive got 1 X Walbro 255 and 1 X HRC 255 equivalent.

 

What alarm/immobiliser do you have ?

 

Just the standard sigma one, normal blue fob. I know they can have problems which was why I hardwired the pump. Does it do the same with the ignition side maybe?

 

Just thought id throw it in there as something to check, not that hard to trace the wires and temp disconnecting the immobiliser out of the question, see if the issue goes away.

 

Id be happy to completely bypass the immobiliser if I knew how. But my knowledge is not so great in this area.

 

It'll be the sigma alarm. The relay for the fuel pump circuit burns out. The relay is in the sigma and not replaceable just follow the wiring from sigma to fuel pump wiring and remove/bridge it.

the immobilizer will still function and cut the starter

if you search on here I've spoke previous about it

 

If you've run a permanent 12V (not from the fuel pump relay) then it shouldn't be the immobiliser. If you're handy with a soldering iron the relays are replaceable in the Sigma, my post here might be useful:

https://www.scoobynet.com/lighting-and-other-electrical-14/1055157-sigma-alarm-issue.html#post12017611

All the relays are available from the likes of eBay if you search for the part numbers printed on the top of them.



The larger relay in the image above is a dual 5A relay so I'd assume this is the one that flashes the indicators, the 3 smaller ones are single 10A relays, I guess one is for the fuel pump, one for the ignition circuit and one other, probably for the central locking.

 

Thats good info Shane - was always under the impression the relays in the immob unit where not replaceable