Fuel Lines - Refitting

[Boatbuoy]

So, my new fuel lines are now fitted and my next task is to re-prime the fuel rail system. Is there any kind of proceedure for this such as bleeding? I intend to pressurise the system several times and check all of the fittings/joints for leaks before starting the engine.

Regards,
Oliver

[optimax sniffer]

I just started it up, then looked for leaks.

Went out for a drive and got everything hot, then a week later retightened most of the hose clips as the hoses has relaxed a little and some were weeping

[ukkid35]

If I were being cautious I would bridge the fuel pump relay and look for leaks, much safer than having the engine run.

[Tanguero]

ukkid35 said:

If I were being cautious I would bridge the fuel pump relay and look for leaks, much safer than having the engine run.

This!!! Many, many times this!

[good40]

optimax sniffer said:

I just started it up, then looked for leaks.

Went out for a drive and got everything hot, then a week later retightened most of the hose clips as the hoses has relaxed a little and some were weeping

If the the above is not a joke then great name Bud Lol
Optimax sniffer

[ukkid35]

good40 said:

If the the above is not a joke then great name Bud Lol
Optimax sniffer

Simply misread as coolant hoses I expect.

[ridds]

Or just switch the ignition on and off a few times. That will pressurise the fuel system enough to spot any weeping fuel.

[Boatbuoy]

OK, cool. Thanks guys.

So what about bleeding. Any requirement to bleed from the highest point, or is the pressure of the system enough to push any air out?

[Tanguero]

It is a recirculating fuel system, unused fuel is returned from the rail to the tank therefore it needs no bleeding.

[jr6yam]

In theory any air bubbles would be forced out of the injectors
It's not like coolant which just goes round & round & round (fuel is at higher pressure too)

[Boatbuoy]

Marvelous! Thanks (as always) chaps.

[Tanguero]

jr6yam said:

In theory any air bubbles would be forced out of the injectors
It's not like coolant which just goes round & round & round (fuel is at higher pressure too)

In fact it pretty much does go round and round. The circuit is pressurised from the pump, through the feed line to the fuel rail & injectors. The pressure regulator on the back of the rail maintains a constant pressure in the rail by bleeding off excess fuel into to the return line which takes it back to the tank at atmospheric pressure.

When you turn the fuel pump on air in the line will go straight through the regulator into the return circuit until the fuel rail fills with fuel, then a steady dribble of fuel will be returned to the tank. No air will come out of the injectors - they wont even open unless there is adequate fuel pressure.

[Mr Cerbera]

Tanguero said:

In fact it pretty much does go round and round. The circuit is pressurised from the pump, through the feed line to the fuel rail & injectors. The pressure regulator on the back of the rail maintains a constant pressure in the rail by bleeding off excess fuel into to the return line which takes it back to the tank at atmospheric pressure.

When you turn the fuel pump on air in the line will go straight through the regulator into the return circuit until the fuel rail fills with fuel, then a steady dribble of fuel will be returned to the tank. No air will come out of the injectors - they wont even open unless there is adequate fuel pressure.

Thanks Peter, always wondered what went on there.

[Boatbuoy]

So, it's all done. I simply cycled the fuel pump by repeatedly pressing the black and red buttons. I'm glad I did as it highlighted 3 leaks which were fettled until it was sorted. I then pressurised the system several times over until I was absolutely sure all was good. Thanks once again all.

Olly