Fueling problems

[TNT ANDY]

Bit of a strange one this one.

I went out with TNT Ross yesterday as he's having a problem with his new fuel system. He's on a C1J running carb and has installed a fuel swirl pot, additional low pressure pump and a new FPR.

The layout is thus - Fuel tank -> low pressure pump -> Swirl pot -> Phase 2 Pump -> FPR ->carb.

The unused fuel goes back from the FPR to the top of the swirl pot.

The problem is that once he has set his idle AFR's to about 14.7 then goes for a run, fueling is fine on boost but once he's done a run his idle afr's are into the 9/10's. His static fuel pressure at idle is about 5-6psi as I believe it should be.

His mixture screw is still in there and in 1 piece and he has stripped and rebuilt the carb with an overhaul kit with still the same problem.

Any ideas on this.

Stotto

[Logg]

Is he running a 2mm needle?

[TNT ANDY]

Is he running a 2mm needle?

Sure is, He has been running this for a while now, We're gonna get on this this week, he's got a few theories to test, so we'll report back our findings.

You think the 2mm needle could be causing problems???

[James5]

Sure is, He has been running this for a while now, We're gonna get on this this week, he's got a few theories to test, so we'll report back our findings.

You think the 2mm needle could be causing problems???


Go back to the 1.7mm I remember Markey Mark having this problem @ frog of the pod with the same fuel setup, he changed the needle jet back to standard and problem sorted.

[Logg]

Go back to the 1.7mm I remember Markey Mark having this problem @ frog of the pod with the same fuel setup, he changed the needle jet back to standard and problem sorted.

Just what I was going to say the 2mm needle doesn't work very well once a swirl port is fitted. Chuck a 1.7pm back in.

[TNT ANDY]

Nice one lads, we'll try this first and see how we get on.

[TNT ANDY]

Well, it was a combination of things.

1. Fuel pressure gauge fitted b4 FPR thus wrong psi at base set up.
2. Throttle plate was catching and not returning fully shut, thus drawing fuel through the main venturie @ idle.
3. We did change the float chamber needle to a 1.7.

All seems to work ok now. Hunting a little, but the AFR's are all good now.

Thanks for the input chaps.

:smokin:

[TNT!hammond]

cheers all. I have a problem but only with my own car with getting so angry i miss things so thanks to Andy for being there to help and Tricky too. Just need to have a little nibble with the fueling at full boost now and maybe lift the preesure a little. car is alot more responsive off boost with the new setup.

cheers again hammy