High Afr's - Dead Pump?

[Ruffels]

Ok today i was playing around with my father in laws new dynodynamics dyno, and hooked up the afr and boost sensors

did a power run, and noticed that at the top end the AFR's are around 14.4 : 1 ... this is too lean for 6000rpm full load ... so i tried a few things to see what the problem was as i think they should be more along the lines of 12.5 (its a s2 r33 gts-t with only a 3" catback as a mod)

i cleaned the afm... afr's still high....

so i did a fuel pressure test... and at the top end the fuel pressure was ~ 40psi .... is this right.. or should it be higher... because i have a feeling the pump may be on the way out and might not be delivering enough fuel!

any thoughts?

[33drifta]

hmm, you have access to a dyno, we should be friends lol sounds like your fuel pump, what power you getting? what other mods do you have?

[Ruffels]

lol @ friends comment.... pay me and you can use it

it made 141.7kw but i'm not concerned about power .... its the afr's im worried about... its just a stock standard Series 2 R33 gts-t with a 3" exhaust.. thats all.

[33drifta]

i was asking about power because if it was over 180rwks or so i would say its time to upgrade fuel pump, but as its low power your stock fuel pump can easily handle it. might be playing up, or could be something else all together. im not sure what pressure it should be but ill be checking back on this topic to find out as im interested to know. good luck mate

[JonnoHR31]

is that 40psi above manifold pressure or above atmo?

if manifold then thats right, if atmo then its too low

[Ruffels]

i'm confused.. i hooked in a fuel pressure guage into the fuel line! ...... ran the car up on the dyno.. and at full boost/load at 6000rpm it was reading 40psi on the fuel pressure guage!

is that 40psi above manifold pressure or above atmo?

if manifold then thats right, if atmo then its too low

[Darren83]

Im actually having somewhat similar problem with my gtr, its making approx 253awkw and towards 7k rpm, its leaning out with a spike of 16, and its detonating.

Im buying a new walbro pump and hopefully it fixes the problem.

Cheers

Daz

[PHA71L]

daz you need to re wire the fuel pump wires all new ones do a search

[HEKT1K]

Ok today i was playing around with my father in laws new dynodynamics dyno

father in law? since when did you get married mark?

hope you get this sorted ASAP

[R31Nismoid]

40psi @ 6000rpm isn't right, thats roughly what it should be @ base i think... so with boost etc should be higher. Either fuel pump needs more juice, or its dying

Don't buy walbro's either

[femno]

Have you checked the fuel filter?????

Afrs should be well under 12 standard.

[Ruffels]

Ric - not married you douche, you know that, but easier way of explaining

Ash - plenty of juice is being provided on a platter for the fuel pump to take... and i think your right... 35-40 psi was base i thought. should increase with boost! i've got a new 040 sitting in my room just chillin out.. might throw that in.

Mat - yeah fuel filter was replaced 3 weeks ago when it was serviced... so would assume thats not an issue... yeah i was expecing around the 12 afr's on stardard tune ... but didnt think a std tune would be under 12! oh well..

got the rest of this week off work now... so will throw the 040 in tomorrow and dump it back on the dyno.. will keep everyone updated!

thanks guys

[R31Nismoid]

Ah by juice - i mean power/wiring hehe, not fuel - sorry!

gotta check the voltage to the pump is spot on

[heller44]

I had a similar issue, rich at idle and cruise, lean on boost. Turns out that the vacuum reference diaphram on the regulator had been destroyed, therefore keeping the fuel at base pressure and not following manifold pressure.

[JonnoHR31]

i'm confused.. i hooked in a fuel pressure guage into the fuel line! ...... ran the car up on the dyno.. and at full boost/load at 6000rpm it was reading 40psi on the fuel pressure guage!

yer thats too low. should be 42psi (i think) base pressure then another psi for every psi of boost. so at 10psi fuel pressure should be 52psi.

I had a similar issue, rich at idle and cruise, lean on boost. Turns out that the vacuum reference diaphram on the regulator had been destroyed, therefore keeping the fuel at base pressure and not following manifold pressure.

had the same thing when my reg died, on boost it leaned out to the point where it simply couldnt fire, just spluttered.

with the stock ecu the AFR's usually drop into the 10s with higher than standard boost

[Darren83]

daz you need to re wire the fuel pump wires all new ones do a search

Hey, thanks, have you had similar problems before? and that solved the problem?

im going to replace the fuel filter and getting a bosch fuel pump instead and earth it properly to see if it rectifies it

[Ruffels]

It was the Fuel pump that was causing the high afr's

put in a new bosch pump, and it fixed the issue!

here's the results for anyone interested

[Darren83]

It was the Fuel pump that was causing the high afr's

put in a new bosch pump, and it fixed the issue!

here's the results for anyone interested

Thats good that the new pump solved the issue.

This is my graph, , notice the sudden spike in afr's in the lower graph.

[femno]

oooo fark me, your lucky you didnt do some real damage running it at 14 under full boost high revs!

You should have stopped as soon as it hit 14!!!!!

[Ruffels]

yeah i know.. didn't have afr's plotted when i did the run, only noticed after i finished the run.

didn't do it again after i had seen that!