Since the rebuild of my R8 Gordini, I'm unable to get fuel flow from the rear fuel tank i.e. the car only runs on the front fuel tank. When I switch to the rear tank, the car conks out after about 60 seconds. During resto, the rear tank was removed and cleaned, and every fuel line is brand new. The rear tank is almost full of fuel, but it just ain't flowin. Any ideas what may be causing this? Suggestions would be appreciated. Really don't want to have to pull engine out again to get to rear tank.
Rear fuel tank on R8G not working - any ideas?
- Thread starter bgbiteme
- Start date
G'day. If you have 2 tanks do you also have 2 filters? When I was a grasshopper (10 years ago) I over tightened a fuel hose clamp at the filter and closed off the fuel system without it becoming apparent. Also if your new fuel line is over sized (like 12 mm) it might be an issue getting suction. 
work your way back from the tap ,have a clamp handy ,for when it eventualy starts to flow ,could be sucking air or pipe blocked ,if you are going to send some air down the pipe make sure the cap is off the tank ,i tried to clear the pipe this way on an old bedford van i had without removeing the cap ,blew a rust hole out of the bottom of the tank ,on a servo for court ,had to get creative with a self tapping screw , in a hurry ,lying on my back in a pool of fuel ,hopeing there were no smokers close by ,the things you get away with when you are young ,the tank was full !
It is very easy to mix up and confuse the rear fuel lines.
First of all confirm that the fuel outlet of the rear tank is free to flow.
Connect a temporary hose to this and blow. should hear bubbles etc at the filler.
Carefully follow the pipework from the tank to the tap . this should enter the tap from the rear.
The front tank fuel line should enter the tap from the front. Simples really...
The bottom outlet from the tap should then feed the fuel line running to the fuel pump.
No filters were originally used, but one between the pump and carbies would be wise.
First of all confirm that the fuel outlet of the rear tank is free to flow.
Connect a temporary hose to this and blow. should hear bubbles etc at the filler.
Carefully follow the pipework from the tank to the tap . this should enter the tap from the rear.
The front tank fuel line should enter the tap from the front. Simples really...
The bottom outlet from the tap should then feed the fuel line running to the fuel pump.
No filters were originally used, but one between the pump and carbies would be wise.
Those rear tanks in theR8/10 are notorious for having blocked internal mesh filters. The mesh filter is internal and impossible to get to are its at the base of outlet/draw tube and even with careful cleaning of the tank, the mesh filter may still be blocked.
As suggested by Steve K, (and I had to do this a few times) run a compressor line in the outlet tube and execute a few short blows, you will hear the bubble, but ensure the filler cap is off first.
I would do this the R10 and run for a few minutes and then it would conk out repeatedly, as the gunk in the tank was too heavy.
Finally I swapped out the tank with a better clean one, and have not had a problem since.
As suggested by Steve K, (and I had to do this a few times) run a compressor line in the outlet tube and execute a few short blows, you will hear the bubble, but ensure the filler cap is off first.
I would do this the R10 and run for a few minutes and then it would conk out repeatedly, as the gunk in the tank was too heavy.
Finally I swapped out the tank with a better clean one, and have not had a problem since.
Can you get rid of the mesh filter and just rely on filters at the carby end?
The mesh is soldered/welded to the base of the steel outlet pipe that sits in the bottom of the tank and solder/welded at the top of the tank forming the fuel outlet.
The only access to the mesh filter - without splitting the tank in half - is to through the petrol filler hole (probably 50mm dia).
The other option is to cut a new hole in the top and install a new pipe into the tank and outlet at the top, but all work must be done with the tank out of the car and empty of fuel.
Having said all the above, bgbiteme's issue may or may not be the mesh, but I just mention the above just in case the cleaning may not have be thorough enough (I went through this and its very frustrating and hope it would help someone).
The only access to the mesh filter - without splitting the tank in half - is to through the petrol filler hole (probably 50mm dia).
The other option is to cut a new hole in the top and install a new pipe into the tank and outlet at the top, but all work must be done with the tank out of the car and empty of fuel.
Having said all the above, bgbiteme's issue may or may not be the mesh, but I just mention the above just in case the cleaning may not have be thorough enough (I went through this and its very frustrating and hope it would help someone).
Why not just poke some hard stick through the outlet and hope the mesh is destroyed enough that it will not get clogged in the future? All you need is one hole big enough that rust flakes will come out. Some suitably thick piano wire might do it.
Have you looked at the breather is working and not Causing a vacuum