Fuel Problem/stalling?

[bj0rn]

s1 rb25 with a walbro intank, nismo 740cc's, ems stinger map sensored.

can hear the fuel pump priming, starts fine, warms up fine. when warm, idle drops as per usual and still goes smoothly. then driving, you'll clutch in and it'll just die. it still gets on boost fine, doesnt hesitate or miss either. just when you slow down and clutch in it'll die then be a prick to start again. might take a minute or two to get started. it also happens if you just give it a stab of the throttle.

things i've checked/done

-new plugs

-swapped coils

-new fuel filter

-swapped fuel pressure regulator

i put a fuel pressure gauge in before the FPR, was reading at 175kpa at idle, dropped down a bit at ~3k revs and then died as soon as i let off the throttle.

so i replaced the fpr and it went to a fairly constant 200kpa on idle. still dies after throttle though. with the vac line disconnected from the fpr it drops to 180kpa.

doesnt appear as if there are any vac leaks either.

suggestions? dying fuel pump? leaky injector/injector jammed open?

Edited November 4, 2010 by bj0rn

[Johny Bravo]

If it's happening consitantly or under the same conditions all the time your best option it to connect it up to a heart monitor(the computer that reads all the magical stuff) and that should tell you whats wrong. Might be a crank angle sensor or something silly like that. Tried cleaning the afm? What fuel are you running it on?

[bj0rn]

yep same conditions. im not too sure how i'd go about connecting the ems to an obd. i dont have one i dont think i have access to one either.

its map sensored not afm.

its running on bp98 and always has been.

only started happening recently. has been tuned and was running just dandy for a few months up until the other day.

[Johny Bravo]

hmm. Don't really know. I've got an r31 so everything is fairly simple. Hopefully there's someone else on here who knows.

[blind_elk]

Hvae you had the injectors cleaned?

If you disconnect the vac line from the fpr at idle, pressure should go UP, not DOWN.

It's probably running too rich at idle - lean it off a bit (if you can - after all, you are using injectors that deliver twice what the standard injector delivers). Give it a bit of extra timing below idle rpm, eg if you have it set for 15 deg at 750 rpm idle, give it 17 at 500 and 19 at 400.

Is the "fuel cut on overrun" working, ie does the EMS shut down the injectors when the throttle snaps shut (like during gear changes)?

[tappy]

Check the ECU, you may be missing something else.

[STATUS]

sounds tune related or the vac line to the ecu is crushed or kinked.

[bj0rn]

ok i've completely made an error, i hooked up the fuel pressure gauge in the wrong place. rookie mistake.

it reads a 40psi at idle & 44psi (stock is 36 / 44 i think) with the vacuum hose disconnected. however, it doesnt increase with revs like it should. the dampner after the pump must be a bit f**ked as well because its not a steady flow. the needle jumps around a fair bit.

i'll look for the vac line to the ecu and trace it. otherwise i'll call my tuner tomorrow and see if he can play with the ems.

will report back when i find out what it is.

any other ideas are more than welcome though

Edited November 4, 2010 by bj0rn

[Rolls]

think you really need a tuner to look at it, could be a thousand things stuffing up and causing it to run rich, stuff up the timing etc.

[Johny Bravo]

Fixed yet?