carb bowl still emptying

[tubbyG]

Last night I drilled out the needle jet to 2mm. Went for a little run, and although a little better, the carb bowl was still emptying http://www.renault5gtturbo.com/forum/images/smilies/icon_cry.gif

so I took apart a spare carb and did it again on another jet, this time drilling a bit further than before. Again it was better, but still emptying when on a long pull, 1st through to 5th. It happens about 5.5-6k rpm in 3rd, and again in 4th about 5k and 5th at 4-4.5k.

I have (apparently) an uprated/phase1 fuel pump bought from CGB last year. So where do I go from here? FPR?

is there a way to tell if the FPR is operating as it should or do I just need to buy a new one?

[5teve L]

You need to drill it all the way through, ideally you need a bit with a flat end & not a point, then reseat the valve by holding it tight & twisting the valve part back & forth till you get a good seal, it's no good just drilling it halfway as you gain nothing....

[tubbyG]

good info there 5teveL, thanks.

Is there a way to remove the valve bit?

[5teve L]

good info there 5teveL, thanks.

Is there a way to remove the valve bit?

I think there is but I never managed it.
I pulled the valve down & drilled it through, if you do it slow the swarf shouldn't end up in the valve, you should have a 2mm hole all the way through. You are doing well on a T2/25 to run out of fuel though @ 18psi.

Also you need to run a gauge in the fuel line to determine if you are running out of fuel before the carb due to poor fuel pump, FPR or just a bad conection through wiring to the pump.

[tubbyG]

I think there is but I never managed it.
I pulled the valve down & drilled it through, if you do it slow the swarf shouldn't end up in the valve, you should have a 2mm hole all the way through. You are doing well on a T2/25 to run out of fuel though @ 18psi.

Also you need to run a gauge in the fuel line to determine if you are running out of fuel before the carb due to poor fuel pump, FPR or just a bad conection through wiring to the pump.

it was a little rich so I upped boost to 19psi. I did wonder, as I have read that the 1.7mm should be ok for upto 20psi. But then with the 285 others have needed to enlarge it a bit sooner

thanks again, I will get a gauge T'd in tonight or tomorro.

so do I drill all the way through so that the drill bit can be seen through the other end, or pops out the ball bit out?............sorry for all the questions, I have searched all over, but have not found a difinnitive guide on how to do it

[tubbyG]

I think there is but I never managed it.
I pulled the valve down & drilled it through, if you do it slow the swarf shouldn't end up in the valve, you should have a 2mm hole all the way through. You are doing well on a T2/25 to run out of fuel though @ 18psi.

Also you need to run a gauge in the fuel line to determine if you are running out of fuel before the carb due to poor fuel pump, FPR or just a bad conection through wiring to the pump.

it was a little rich so I upped boost to 19psi. I did wonder, as I have read that the 1.7mm should be ok for upto 20psi. But then with the 285 others have needed to enlarge it a bit sooner

thanks again, I will get a gauge T'd in tonight or tomorro.

so do I drill all the way through so that the drill bit can be seen through the other end, or pops out the ball bit out?............sorry for all the questions, I have searched all over, but have not found a difinnitive guide on how to do it

[5teve L]

it was a little rich so I upped boost to 19psi. I did wonder, as I have read that the 1.7mm should be ok for upto 20psi. But then with the 285 others have needed to enlarge it a bit sooner

thanks again, I will get a gauge T'd in tonight or tomorro.

so do I drill all the way through so that the drill bit can be seen through the other end, or pops out the ball bit out?............sorry for all the questions, I have searched all over, but have not found a difinnitive guide on how to do it

When you look through the hole you will see the needle that seals it, you just need to drill down so you have 2mm all the way down this hole, thats why I said you need to use a flat drill bit as you can get all the way down without drilling the needle part, then like I say push the ball down & twist it back & forth to make the needle seal again.
Make more sense ?

& you need to be seing 4psi above boost pressure.

[bigdur]

You can just buy a brand new 2mm unit off ebay Germany instead.

[Brigsy]

The big question is your fuel pump delivering the goods? have you changed the fuel filter recently? fuel pressure regulator working ok??

Id personally stick with the stock 1.7mm jet and fit a malpassi fpr, bump the fuel pressure up to 6 psi at idle. It will drive far better than a big needle valve.

[tubbyG]

When you look through the hole you will see the needle that seals it, you just need to drill down so you have 2mm all the way down this hole, thats why I said you need to use a flat drill bit as you can get all the way down without drilling the needle part, then like I say push the ball down & twist it back & forth to make the needle seal again.
Make more sense ?

& you need to be seing 4psi above boost pressure.


much clearer now bud, cheers :agree:

[tubbyG]

You can just buy a brand new 2mm unit off ebay Germany instead.


yeah I have seen them available. I just thought I would give it a bash as I had 3 spare carbs in pieces - plus Im a tight cnut:laugh:

[tubbyG]

The big question is your fuel pump delivering the goods? have you changed the fuel filter recently? fuel pressure regulator working ok??

Id personally stick with the stock 1.7mm jet and fit a malpassi fpr, bump the fuel pressure up to 6 psi at idle. It will drive far better than a big needle valve.


I hope the fuel pump is working as it should, but I have not yet measured fuel pressure. Was labelled as an uprated/phase1 fuel pump from cgb.

I havent checked the fuel filter yet either, looks like I will check tomorrow when I go to check fuel pressure. I will give the drilling another go - fingers crossed I just did it incorrectly