going lean

[Fordy]

evening all

Been chasing a lean issue on boost had the aem in the exhaust and heres what i'm getting

3rd -5th gears, cruising along then foot flat to floor goes from a rich cruise of 13.5~14.0 to straight off the scale lean coughs a bit then drops back into 13~13.5 on boost (boost set at 10psi standard t2)

Now things i've changed so far is the fuel regulator for a brand new renault item

Still the same maybe a bit stabler a reading if anything

Now the carb as been rebuilt with new seals n everything, so i rechecked the accel pump setup with the 5mm drill bit and still the same

Tried making the accel pump open far to early now its dipping the fueling rich then going off the scale lean then into 13-13.5~s

carb jets are all standard and the 2nd stage is a loose 1mm or 1.1mm but i havent got a 1.1mm drill bit

sadly a leaking rocker cover fibrewasher ended play :( soon be fixed tonight

i've got a feeling its the fuel pump not being able to keep up? what would the more experienced 5 owners think?

[Tony Walker]

thats where the first stage should be coming in to play surely? check thats not blocked?

[Fordy]

what size should the 1st stage be? as i've got a 100 in there atm :confused:

its the first time i've tried sorting this carb so getting a good idea of what jets to adjust would be great

just want to make sure the pump isnt giving up and making the lean running before drilling out the carb :eek:

[Brigsy]

Fuel filter blocked? Also check the pipe to the fuel pressure regulator for splits.

[Tony Walker]

The 5GTT

Uses the 32DIS 854 and 931.

Standard jets are:

1.2mm main jet.
1.25mm air corrector.
1mm 1st stage enrichment jet.
1mm 2nd stage enrichment jet/bush.
0.45mm idle jet.
0.40mm accelerator pump jet.
1.7mm needle valve.

[Fordy]

cheers tony :)

[Tony Walker]

if its running fine on full boost id say the fuel supply is sufficient, its the initial throttle opening your complaining of right??? so that really can only be accelerator pump, 1st stage. maybe check vaccuum pipework to aie possible ignition timing causing a slight miss and lean reading?????

[Fordy]

just got back in from the garage and :D

Took the carb off the car after fixing the rocker leak

Been stripping the carb on the car and a known good carb in my garage

Gave this little bugger a blowy and it just wasnt performing :disagree:

http://i723.photobucket.com/albums/ww235/fordy51/tommy%205/IMG_20110514_212254.jpg


So swapped it out with a spare good one, reset the accel pump perfectly with a 5mm drill bit :smokin:

fingers crossed its ok tomorrow

[Fordy]

ok had the car out today and its better but still not perfect

at 3k rpm if I got from cruise to wot in 5th it'll go round to lean then settle back onto mid 12's till 4k -4500ish rpm then it goes tapers from 12s 11.5s till red line

so the Higher scale 2nd stage is fine but the lower end is still too lean for my liking on a sensitive engine

and I'm only at actuator pressure of 10psi still lol

am I right in think drilling out the 1st stage will richer it up slightly lower down?

also when I'm down on -vac readings I'm running low afr of 12-13s and 14.5ish around 0psi so guess I can't play with the main jet at all?