fuel pipes

[jim sri]

on the nova i have two pipes coming from the petrol tank to the engine bay, a brown and black one. may sound stupid but which is fuel in and fuel return. the pumps etc are disconnected so cant tell from that. cheers for any help in advance.

[Aragorn]

i seem to recall that one of the pipes is fixed onto the bulkhead, that is the return pipe

the other pipe aint fixed to the bulk head as it normally goes to the pump

dunno if this helps since it might not be attached to the bulkhead anymore :D

u prolly find it doesnt actually matter tbh

[Manta Mad]

Would agree that it doesn't really matter which way round they are since you have to make the connections to the tank/pump/injectors with rubber hose anyway.

What model of Nova is it you have?

[DERTGREMLIN]

its a 2 litre nova (or will be once the fuelling is sorted!)no pipes attached to the bulkhead nemore unfortunately. the black pipe is thicker so im guessing that must be the feed and the brown pipe thinner must be the return.

[brian]

go with the thicker as the feed

[carltoncrazy]

if remeber right,the darker pipe is the feed
cant remeber wot colour

[mikeoxford]

check the internal bore (hole) of the pipe.

generally the thicker the pipe the bigger the bore - but sometimes it aint!!!

also im assumin you have a fuel pump somewhere??? if u r using the one at the rear of the car you WILL have to use the right one as otherwsie the pump at the back will be pumping up the return feed, and ur engine willbe working off the un pressurised line - not good.

[Manta Mad]

Just a thought - are the fuel pipes that are on the car plastic ones? - I had heard that the plastic ones as fitted to the SPi Novas are not suitable for the higher pressure pumps that the GSi etc (and probably your 2L)have. Anyone know if this is true?

[Aragorn]

could be right there

SPi runs 0.76 bar fuel pressure

MPi (GSi anyways) runs 3bar fuel pressure (the gte runs slightly less iirc)

not sure if the SPi hose is rated to 3 bar :/

[Manta Mad]

I am more used to the Mantas fuel injection system which is also around 3 bar and uses steel pipes (oh and how they rust :evil: ) was quite surprised to see plastic pipes on my SPi Nova that is until I took out the tiny fuel pump!

Had a look at mine tonight, it was dark with but I am sure the black pipe is the feed.

[jim sri]

i have got a gsi fiel pump, but its in the engine bay, so the fuel between the tank/pump are under not much pressure. we got the 2 litre running tonight, and its running fine, but after trial and error it is defo the thicker black wire which is the fuel feed.
:D

[Manta Mad]

watch the pressure in your fuel return line as this will be pressurised right back to the tank.

[mowgli]

from various homemade fuel setups (BODGES), I would say that if you are going to fit an injection motor, you should fit a GTE/GSI/SRI tank & fuel pump assy. You get a bigger tank, and the fuel supply is better.

With a 1.2 twin pipe tank, there is no need for a continuous fuel supply, cos the carb bowl always has enough fuel to cope, and the diaphragm fuel pump will always keep pumping. But if you are going hard round a right hand bend, all of the fuel goes to the left hand side of the tank. On a carb engine, this is not a problem, cos not much fuel is actually pumped per second.
On an injection setup, the fuel is pumped at about 3 bar (45psi) & 1 litre per minute. If you have less than 1/4 of a tank, the pump could suck in air causing the engine to cough, and stall (I have had it happen)

The GM Bosch pump does not like being run dry.

The feed to the pump is always a compromise, going from an 8mm pipe on the tank to a 12mm pump inlet causes quite a big restriction, the 8mm pipe will only flow about 40% of the flow of the 12mm pipe, this can cause the homemade inlet pipe to collapse.

With the nylon fuel lines, the 8mm one is the feed, and the 6mm one is the return. Use the 8mm one as a new return, (remembering to swap the ends about) it won't run at very much pressure, as it vents to the tank. Get a new 8mm nylon pipe for the feed. Use High Pressure braided hoses for the joints with good jubilee clips. The best source of high pressure nylon hose is a truck spares shop. Truck hoses run at 8 bar, just make sure that they can be used for petrol, ask for written proof.

Hope this helps, I once got petrol in my right eye, I can assure you that pain isn't a big enough word to describe it, so be careful.

[jim sri]

nt reason. i know the engine is mechanically sound and the wiring etc are all up to scratch, so we kinda guessing it is fuel probs. wud fitting gsi fuel lines from the tank help much because i really cant be bothered to change the tanks. we have a donor gsi, and have tried to get the tank out, but she aint budging at all!
or am i gonna have to get the tank too? :evil:

[mowgli]

if you have undone the straps then you may need to prize it out with a big screwdriver/crowbar, they have tarred felt pads on top to stop them rattling about.

Remember GM only make a different part if it is necessary, I'd still say fit the tank