Injection fuel pipe HAS to be metal?

[Ian Macquarie]

I'm thinking of changing from Carbs to injection. It would be much easier to get the new fuel pipe in if it was plastic, (Nylon?)like the original. Is there anyreason why it shouldn't be? After all the flexible bits from the pump to the filter and main pipe to injection rail will be hose, why not all of it?

[EFA]

It needs to be rigid and strong to hold the injectors in place.

 

When the fule rails break on the Jenvey throttle bodies (as they did on the early versions), squirting fule over a hot engine at 60psi is not a good thing.

 

I got away with this twice!

 

 

 

Arnie Webb

Organiser- L7C Le Mans Trip

To book for this years Le Mans Trip see The Le Mans Trip Website

It really is very very very very full now!!!

[Ian Macquarie]

You do know haw to make me worried! Are the current fuel rails (the cast ones with push on connectors) still prone to this? I'd anticipated using rubber (injection) hose for the final connection from the fixed pipe above the gearbox to the fuel rail.

 

Ian

[Ian Macquarie]

Sorry, I also meant to ask - Where did they break? the fuel pipe or the "bracket" that holds them onto the throttle body?

 

Ian

[EFA]

Ian

 

They broke on the bracket, where it welds to the rail.

 

The whole rail was re-designed to stop torsional loading on the bracket when it was fitted, so the new ones are OK.

 

Incidently, I think most cars with the Jenvey setup fitted to replace carbs will use -8 fittings on braided hose.

 

 

 

Arnie Webb

Organiser- L7C Le Mans Trip

To book for this years Le Mans Trip see The Le Mans Trip Website

It really is very very very very full now!!!

[Chelspeed]

I would think it's not good to use solid metal pipe all the way to the injectors because the vibration of the engine relative to chassis will fatigue the pipe. Nearly everyone uses flexible pipe for the last bit from the chassis to the engine.

 

I use -6 aeroquip stainless braided hose for the whole lot from the tank to the engine and back as a couple of metres of pipe is cheaper than the fittings to go from solid to hose at each end.

 

All 4 Jenvey fuel rails that I have used on my engine over the years have had -6 fittings on the ends.

[Chelspeed]

Oh yeah, forgot to say Arnie, I had the same type of fuel rail break on an old Jenvey fuel rail.

 

Did the injectors stay in the engine and cause a constant high pressure leak? My injectors are push fit into the manifold but securely clipped onto the fuel rail. If the fuel rail mountings break the injectors will come away with the rail and will only leak when the ecu asks them to open. Mind you this just means a nice spray pattern for the fuel across the engine rather than a single spurt so probably just as bad.

 

My worst Se7en moment was the first sprint after doing the injection mod. Half way down the first 400m sprint from the start line the small bore manifold vent water pipe to the expansion tank blew off (my fault I used a tyrap as I didn't have a jubillee small enuff). This caused a spray of greenish colour liquid to spray out of the bonnet vent by the inlet manifold (and fuel rail area)straight at my helmet. I thought petrol and was half out of the car before thinking perhaps I should brake first, 200m skid to a halt and I was half way across the field before stopping. My mechanic and missus were stood on the start line in hysterics.

[Mike Bees]

Ian,

 

Arnie's & co are talking about the fuel *rail* which holds the injectors in place. I think you're talking about the piping from the tank to the rail? Whatever you get, make sure it can handle the high pressures associated with fuel injection. Flexible fuel hose comes in low pressure types for carbs & high pressure types for injection.

 

Mike

[Ian Macquarie]

Mike,

 

Yes it is the fuel pipe from the tank to the front of the car that I'm talking about. I was wondering if I have to try to get metal one along the tunnel (that has a differential and prop shaft in the way) or whether i could use one similar to the plastic one that Caterham use for the low pressure system. In air applications Nylon tube of about that size is probably good for a couple of hundred psi. so the 30 to 40 used by the injection system shouldn't be a problem - I was just wondering if there were any other reasons why it would be unsuitable (regulations?) I've read in one or two places "you need a metal fuel pipe to the front of the car" but never an explanation as to why.

[EFA]

Graham,

 

You're right its -6 connectors. As the girl on the Renault ad says..."size matters"

 

I didn't have the clips on the tops of the injectors so it was the top seal which broke.

 

I was out of the car even sooner than you. Funnily whilst I was waiting for the evaporation process I was mentally calculating the insurance claim if it went up....

 

According to my wife, it sadly didn't.

 

Ian, for the long pipe runs you want braided aeuroquip type hose. Its a real pig to get down the tunnel, but at least you know that a UJ failure on the prop means you'll only get a dneted tunnel, not burnt alive!

 

Arnie Webb

Organiser- L7C Le Mans Trip

To book for this years Le Mans Trip see The Le Mans Trip Website

It really is very very very very full now!!!

[Mike Bees]

Ian,

 

As Arnie says, I wouldn't use the plastic return pipe stuff for the pressure feed. For all you know it could be a different type of plastic to that used in air applications (in fact I've got a roll of the latter at home and it is quite different).

 

Mike