Jump to content
SAU Community

Recommended Posts

Hey guys. Decided to upgrade my fuel pump for e85. Was running a walbro 255 on stock wiring and working fpcm. Was feeding 250rwkw with AFR in the low 11's top end no problems.

I upgraded to dw340 lph e85 pump. Installed in same configuration as walbro and went for test drive. Ran well but was leaning out, top end AFR of 13+ was occurring. Was thinking this pump requires more voltage.

I went back home and rewired the pump with a 30 amp relay and wiring to the battery. Went for test drive again and ran well cruising around but extremely rich when on boost, I saw AFR of low 9's. Ran like shit, WTF.

Not sure what's going on.

I was assuming that my stock fpr would cope. Is it not able to?

Is it because I had the car tuned with the fpcm and now running without?

Maybe the walbro was weak and the car was tuned on low fuel pressure?

Any ideas and advice or explanation of what's occuring appreciated.

Remember the check your rubber fuel return line in the engine bay for a restrictor, it feels like a hard bump, mine was down near the damper that turns 90deg. My rail pressure was out of control with a walbro 460 because of the restrictor.

Remember the check your rubber fuel return line in the engine bay for a restrictor, it feels like a hard bump, mine was down near the damper that turns 90deg. My rail pressure was out of control with a walbro 460 because of the restrictor.

Thanks for that, I'll have a look tomorrow.

Had another play around this morning. Couldn't find any restrictor in the return line. I went back to stock wiring, same lean result. I then grounded the pump -ve to take out the fpcm circuit and back to extremely rich again. At this point I'm thinking about putting the walbro back in, checking AFR again and seeing if the wiring changes have the same effect.

If the same thing happens I'm thinking possibly the fpcm is stuck in low voltage mode and was tuned like that. Thoughts please.

Moving forward, to correct the rich conditions with direct power, retuning will be required. Correct?

I had the same issue when I swapped out a Walbro pump for a Nismo. Even though both pumps are quoted as a similar flow rate, the Walbro flowed significantly less - I had to take around 10% of fuel out of the tune to correct the Air/Fuel ratio change.

I had the same issue when I swapped out a Walbro pump for a Nismo. Even though both pumps are quoted as a similar flow rate, the Walbro flowed significantly less - I had to take around 10% of fuel out of the tune to correct the Air/Fuel ratio change.

Where your idle and cruise AFR OK or rich. Mine are fine, its only when on boost. I'm pretty hesitant on playing with the map myself at this stage. Did you take fuel out of the whole map or just parts of it?

I had the same issue when I swapped out a Walbro pump for a Nismo. Even though both pumps are quoted as a similar flow rate, the Walbro flowed significantly less - I had to take around 10% of fuel out of the tune to correct the Air/Fuel ratio change.

the std fpr should adjust for this. sounds like your walbro was lazy.

Stupid question maybe, but can't you just adjust you base fuel pressure off your fuel regulator.

Yep stock reg isn't adjustable but my idle and cruise are fine so even if I could adjust fpr it probably would lean out the idle too much.

Where your idle and cruise AFR OK or rich. Mine are fine, its only when on boost. I'm pretty hesitant on playing with the map myself at this stage. Did you take fuel out of the whole map or just parts of it?

Yeah the idle and light cruise wasn't too far off, the on boost part of the map required the largest change

Thanks for all the replies guys[emoji106] . I had a quick play with the master fuel trim and took out 20% fuel and it was still pig rich on boost. Time for professional help as I don't feel like losing a perfectly good engine due to me stuffing around with it, I also need the maps to be spot on as it will be the base for my flex tune. I'll update when I get it sorted.

  • Like 1
  • 2 weeks later...

Just had the car retuned properly and it appears the old walbro was indeed on the way out. Now the shape of the map is a lot flatter, idle is better than ever, throttle response feels sharper and more importantly the car made an extra 12rwkw bringing it up to 260[emoji3], not bad for a HG 21u h/flow turbo. AFR is rock solid now across all gears and plenty of extra fuel available for e85 goodness.

  • Like 1

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • Hi, SteveL Thank you very much for your reply, you seem to be the only person on the net who has come up with a definitive answer for which I am grateful. The "Leak" was more by way of wet bubbles when the pedal was depressed hard by a buddy while trying to gey a decent pedal when bleeding the system having fitted the rebuilt BM50 back in the car, which now makes perfect sense. A bit of a shame having just rebuilt my BM50, I did not touch the proportioning valve side of things, the BM50 was leaking from the primary piston seal and fluid was running down the the Brake booster hence the need to rebuild, I had never noticed any fluid leaking from that hole previously it only started when I refitted it to the car. The brake lines in the photo are "Kunifer" which is a Copper/Nickel alloy brake pipe, but are only the ones I use to bench bleed Master cylinders, they are perfectly legal to use on vehicles here in the UK, however the lines on the car are PVF coated steel. Thanks again for clearing this up for me, a purchase of a new BMC appears to be on the cards, I have been looking at various options in case my BM50 was not repairable and have looked at the HFM BM57 which I understand is manufactured in Australia.  
    • Well the install is officially done. Filled with fluid and bled it today, but didn't get a chance to take it on a test drive. I'll throw some final pics of the lines and whatnot but you can definitely install a DMAX rack in an R33 with pretty minor mods. I think the only other thing I had to do that isn't documented here is grind a bit of the larger banjo fitting to get it to clear since the banjos are grouped much tighter on the DMAX rack. Also the dust boots from a R33 do not fit either fyi, so if you end up doing this install for whatever reason you'll need to grab those too. One caveat with buying the S15 dust boots however is that the clamps are too small to fit on the R33 inner tie rod since they're much thicker so keep the old clamps around. The boots also twist a bit when adjusting toe but it's not a big deal. No issues or leaks so far, steering feels good and it looks like there's a bit more lock now than I had before. Getting an alignment on Saturday so I'll see how it feels then but seems like it'll be good to go       
    • I don't get in here much anymore but I can help you with this.   The hole is a vent (air relief) for the brake proportioning valve, which is built into the master cylinder.    The bad news is that if brake fluid is leaking from that hole then it's getting past the proportioning valve seals.   The really bad news is that no spare parts are available for the proportioning valve either from Nissan or after market.     It's a bit of a PITA getting the proportioning valve out of the master cylinder body anyway but, fortunately, leaks from that area are rare in my experience. BTW, if those are copper (as such) brake lines you should get rid of them.    Bundy (steel) tube is a far better choice (and legal  in Australia - if that's where you are).
×
×
  • Create New...