Jump to content
SAU Community

33gtst Fuel Pump Upgrade, Now Running Rich, Fark!

admS15

By admS15,
in Engines & Forced Induction

 Share

Recommended Posts

admS15 Grand Master

admS15

Posted
Posted

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.

dr phil Collaborator

dr phil

Posted
Posted

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.

admS15 Grand Master

admS15

Posted
  • Author
Posted

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.
admS15 Grand Master

admS15

Posted
  • Author
Posted

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?

Ryno Experienced

Ryno

Posted
Posted

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.

admS15 Grand Master

admS15

Posted
  • Author
Posted

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?
Trex Grand Master

Trex

Posted
Posted

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.

admS15 Grand Master

admS15

Posted
  • Author
Posted

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.
Ryno Experienced

Ryno

Posted
Posted

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

admS15 Grand Master

admS15

Posted
  • Author
Posted

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...
admS15 Grand Master

admS15

Posted
  • Author
Posted

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • Matt Z
      SAU NSW - Archies Flame Grille Meet & Cruise to Kurnell

      By Matt Z · Posted

      Join SAU NSW for a flame-grilled feed & flame-spitting cruise! Sunday 17th August 2025 3:30PM Meeting Archies Flame Grille Sylvania Waters 4:45PM Cruise Departure 5:15PM Arrival at Cape Solander Kurnell Meet Location: Archies Flame Grille Final Destination: Cape Solander Kurnell *Disclaimer* There will be a lead and follow car so no one should get lost. If you would like to attend or bring others along please put your name down and a +1 as numbers will be needed prior! This is NOT a race and we will all be adhering to all road rules. If this is what you want please come to one of our many track days. This is an official SAU:NSW event and will be run under a CAMS permit. One of the things that really sets our club apart is our commitment to being true enthusiasts. When on normal roads we strive to maintain good relations with the authorities as well as the public in general. When attending one of Skylines Australia NSW events please try to: • Be aware of surrounding environment and act accordingly. • Drive courteously on the state’s roads as a true enthusiast should. • Understand how important it is to maintain the good name of SAU NSW and thus, treat others accordingly. • Any misbehavior will not be tolerated and you will be asked to leave.
    • Ozdavroz
      WTAC 2025

      By Ozdavroz · Posted

      Yeah good luck out there! Will be good to see a mighty GTST going harder than the GTRs
    • bcozican
      WTAC 2025

      By bcozican · Posted

      i will be there 😁
    • patrickxdf12
      Squeaking clutch/throw out bearing

      By patrickxdf12 · Posted

      Hello!  i just finished manual swaping my r34 skyline with a r33 rb20de box(RB71C)box  When the car is running it squeaks crazy loud and it was smoking from the gearbox area. The gearbox is fine it was tested. The clutch slave cylinder seems like it doesn't fully releases the clutch. I want to ask if this noise is from the throw out bearing or could it be the clutch assembly or disk att.xFliq87Gzw6kImKBVqDebXkj0fBqymk0JaYeP3_3SlM.mp4
    • RP1421
      S15 Spec R

      By RP1421 · Posted

      A few small updates since the previous post and lessons. I decided to do a little interior light upgrade on the 110. I quite like the iilumo items, even if they're a bit of a premium over other brands. You'll also note the Stedi Fogs, that will go into the S15 fog lights as I needed to match the bulbs since I got the new ones earlier. I hope they fit as the body is quite a bit longer than your normal bulb.  Annoyingly, I managed to trip the fuse, which normally wouldn't be an issue until I located the fuse. I can't say I've ever come across this. I had lucked out that someone nearby had a spare, but oddly enough Toyota dealerships seem to keep this in stock. I ordered some to keep in my stash and as luck would have it, someone else nearby tripped the same fuse so I passed on the favour.  I also did a little service on the 110 ahead of some additional work coming up. It's been annoying that Goleby's stopped carrying this particular HKS filter for the 110, so now I need to keep them on order from Japan. I also took the opportunity to install a bash plate and number plate riser. The plate riser is such a cheap but nice fix to help really tidy up the car. I'm tempted to now also replace my headlights, on this car. Both items were from Project Aero.    I also needed to replace the rear tyres on the 110, and after trying to get it aligned learnt that I need to replace some bushes in the front end, so that's next.  Closing out this update with a nicer picture as always! 
×
×
  • Create New...