69 replies to this topic

[Horace]

Not checked the fuel pump relay yet. Gonna do that tomorrow. FLD: Thanks for the offer. Could be of use. Normally, I could hear the fuel pump priming, then it would stop. Now the whirring noise seems to be constant, and doesn't stop. This coupled with no pressure at the rail seems to point to fuel pressurisation issues? However, the constant whirring noise must mean that the fuel pump relay is powering the fuel pump, does it not? Would a Tech2 diagnostic pick up internal valve failure on the fuel pump?

Edited by Horace, 23 March 2011 - 08:31 PM.

[Horace]

This sounds familiar! I had starting issues ages ago. When you press the fuel rail valve you should have a good metre jet! Mine cleared the car and went up the wall of the house! What I was finding was that the internal valves in the pump had failed. The pump primed but the pressure went straight away. Was a slag to start. Have a try at this....turn on the ignition and listen for the pump priming. DO NOT TRY TO START IT. Turn it off. Do this on / off routine several times and hopefully it should retain enough pressure. Then try to start it. If it starts the pump will run continuously and you'll be fine. Let us know how you get on. After swapping my pump its been fine. I also noticed how loud the old pump was compared to the new one. If it is your pump let me know as I have a cliffie pump to fit (been on the to do list for ages) so my old one will be going spare.

Did you have the metre jet with the knackered fuel pump? Or was that after the fix? How did you diagnose the internal valves?

Will try your method tomorrow. Thanks.

[FLD]

1 metre jet with the engine (and therefore pump) running. When the valves were knackered there was no pressure as soon as you turn it off. The pressure should remain for at least a week. New pump and I get a good jet even if stood for weeks. EDIT: if the pump is running the relay is working!

Edited by FLD, 23 March 2011 - 09:09 PM.

[Horace]

How easy is it to change the fuel pump?

[techieboy]

How easy is it to change the fuel pump?

Not very much fun, I'm afraid.

[FLD]

Depends if your car has been modded for it. TIS route is a ball ache. Pikey route is easier. Seats out, Shelf out, Pump cover off (4 bolts) Disconnect pump Move wiring etc the hell away from the hole and protect the area from filings Jigsaw in a larger hole (access hole is too small for the pump) Pump is held in by a big circlip Pull out the pump section Pump is a small bit in the middle Replace pump and reassemble Note, your fuel guage will read differently! Give me a shout if you want some pics, I've got the shelf out of mine at the mo.

[Horace]

Jesus! Is there a definitive way of proving the pump is knackered? Pics would be appreciated, but only if all else fails then! Best to take the piccies whilst the shelf is out eh? Why will the guage read differently? Just read the TIS! I ain't doing that! And I ain't paying anyone to do it either!! Just a case of removing the undertrays, disassembling the whole gear linkage, disassembling the handbrake assembly, disassembling the wishbones, disassembling the engine mounts, removing the fuel lines and fuel filler pipe, then dropping the fuel tank!!

Edited by Horace, 23 March 2011 - 09:48 PM.

[techieboy]

Jesus!

Yep, it's not a job to undertake just for the fun of it.

Why will the guage read differently?

I'm not sure it will. As long as you don't mangle the float for the fuel level sender, it should make no difference. Mine has been fine with the upgrade to the ProAlloy long range tank and the later fuel pump upgrade. At least I think it has, I haven't run out of petrol yet.

[Horace]

Just a thought (in desperation): If my battery is on its last legs, and it's the only thing that powers the fuel pump when priming the system, could it be that there's not enough juice (power) to properly pressurise the system?

Edited by Horace, 23 March 2011 - 10:00 PM.

[Mangham54]

Just a thought (in desperation):

If my battery is on its last legs, and it's the only thing that powers the fuel pump when priming the system, could it be that there's not enough juice (power) to properly pressurise the system?

I would doubt it as the cranking the engine is where I would expect the largest battery load to be... So if the engine is turning then surely there must be enough charge to prime the fuel rail.

[techieboy]

I'd have thought the battery wouldn't have the oomph to turn the engine over if it's was that fubar'd. Starter will definitely need more power than the fuel pump.

[FLD]

Some excelent pictures in Vocky's guide to fitting a cliffie pump. Its on page 2 of the guides section. The fuel level indicator in mine isn't/wasn't the most reliable. Ran out when it was showing 6L left. Having swapped it it now seems to read high. I always err on the side of caution now and keep it full!

[techieboy]

Having swapped it it now seems to read high. I always err on the side of caution now and keep it full!

Maybe mine has taken to under-reading then and that's why I've spent the last 3 trackdays watching fuel cascade out of the filler on left handers, in the side mirrors. A little more worrying now I've got a de-cat and the possibility of flames coming out of the exhaust. Rear clam was absolutely dripping in fuel at Snetterton after a top up (too theoretically about 36 litres of the 48 litre tank).

No idea why it's suddenly started doing it.

[Mangham54]

Having swapped it it now seems to read high. I always err on the side of caution now and keep it full!

Maybe mine has taken to under-reading then and that's why I've spent the last 3 trackdays watching fuel cascade out of the filler on left handers, in the side mirrors. A little more worrying now I've got a de-cat and the possibility of flames coming out of the exhaust. Rear clam was absolutely dripping in fuel at Snetterton after a top up (too theoretically about 36 litres of the 48 litre tank).

No idea why it's suddenly started doing it.

Be careful Matt... One VX has already been lost to a fire in the last 12months (RIP Kerry) and we don't need another going that way.

Coincidentally mine always under reads by 2 litres - but other than the effect of petrol sloshing in the tank on corners it is always bang on right (when you add the missing 2litres to the digital read out).

[Horace]

Quick update:

Here's a piccy of the 2 multicore plugs behind the header tank. They look manky but they were clean and dry inside.




Here's a piccy of the ECU earth strap. I cleaned the connection up, but it really wasn't suspect




So I decided to have a look at the relays in the boot. I had a peer inside and saw the relay cover. The screws were a right pita to get out and the rubber inserts just spun round in the wheel arch. After much swearing and pissanting about, I managed to get the cover off..... and was presented with a small motorcycle battery! Doh!!

So I started taking the right cover off this time, but had to take the boot carpet and liner out for access. Here's what I found (boot floor)




And the relays and cabling were looking decidedly damp




Notice how the relays are marked up to match the coloured stickers. Has this been worked on before?


Took the relays out. Some of the relay sockets were showing signs of oxidisation. I'll need to clean these up somehow.




One of the grey relays was a little oxidised on the main contacts, but not major. The others were all okayish. I took the relay covers off just to be sure, and all looked clean and dry in there.







I cleaned all the contacts up with emery paper no problem.

[Horace]

Went back to the car to position a hair dryer to blow warm air into the relay sockets, and to generally dry out the loom, when I noticed the fuses!





Those two yellow 20A fuses look in very bad shape. They haven't blown, but the plastic has melted and bubbled, and one of the contacts in particular has a thick coating of melted crap and oxidisation on it.

The main 50A fuse had oxidisation of one of the contacts, but looked healthy otherwise.




This is my prognosis (fingers crossed): I suspect that these fuses have been shorting out due to dampness. The heat generated has melted the plastic. Because they've been shorting before the actual 'fuse' element, the fuse hasn't blown. The shorting out of these fuses has lead to not enough power being fed to the fuel pump, so the fuel pump hasn't enough juice to pressurise the fuel rail. The deterioration of these fuses would coincide with the gradual onset of my issues (rather than a fuse blowing and the issue becoming immediately apparent).

I've got replacement fuses. And tomorrow I'm back in the boot.

Wish me luck!

[techieboy]

Fingers crossed that's the root of your problem. The 20-amp fuses certainly don't look too healthy - have you been running anything with hefty current demands from the cigarette lighter circuit?.

[Horace]

Err... Why would you ask that? These fuses are not connected to the the cigarette lighter circuit surely?

[Darcini]

So I decided to have a look at the relays in the boot. I had a peer inside and saw the relay cover. The screws were a right pita to get out and the rubber inserts just spun round in the wheel arch. After much swearing and pissanting about, I managed to get the cover off..... and was presented with a small motorcycle battery

That is exactly the sort of thing I would do

Those fuses look promising........

[Horace]

Hey Nige, You can see your green waitrose box in the background of the yellow relay