At what point does the 255hp become insufficient?

[92awddsm]

As the title states, when is an upgrade from a single walbro 255hp needed. I have recently swapped out cams, intake, injectors, tb, and ic piping and found that anything above 25psi starts going really lean(12.30+) and knocking like crazy. With my old setup, I was able to run 28psi on 93 pump gas but since the upgrades, everything has changed. I have gone over my entire fuel system and Ive come to the conclusion that my fp is either being overworked or just tired. My guess is that it may just be getting old but I would like some to chime in with real life experience.

 

[e85_4g63]

It depends on the tune and air flow really. I've personally seen a 1g do 529awhp on a single wally 255HP with C16

 

[92awddsm]

It depends on the tune and air flow really. I've personally seen a 1g do 529awhp on a single wally 255HP with C16

Im sure. I was able to squeeze 476 out of mine on 110, 455 on pump with the old setup, 11.3-11.7afr, 2-3 counts knock and 23* max timing. Timing curve is close to the same, afr is in the11.0 range, and timing maxes at 20*. Once I get to 25-26psi, afr starts going lean and I feel it starting to surge. Im only seeing around 70%dc on my 1150 injectors before it starts to act stupid. As for airflow, I havent logged it yet. Trying to figure out the problem before I even worry about logging airflow.

 

[VETTE_50_TH]

Base fuel pressure im assuming is at 38.5? And your FP is rewired? Why dont you bump the pressure up to a 2g amount and retune with that. That may help.

James

 

[92awddsm]

Base fuel pressure im assuming is at 38.5? And your FP is rewired? Why dont you bump the pressure up to a 2g amount and retune with that. That may help.

James

I tried a base of 38 and 43. Both still seem to act the same. Thats what makes me think that my pump just isnt keeping up. And yes, fp has been rewired now for 9yrs.
If it makes a difference, Im running a -8 feed from the tank to the rail, venom rail, -8 from rail to fpr, and 3/8" hard line for return. This is nothing new either. Its had the same feed, rail, and return for 2yrs now. Same fpr that has been on the car for 5yrs. Only thing that has changes as far as the fuel system is concerned is that I went from 780cc injectors to 1150cc injectors. And yes, my fuel filter is clean.

 

[VETTE_50_TH]

I tried a base of 38 and 43. Both still seem to act the same. Thats what makes me think that my pump just isnt keeping up. And yes, fp has been rewired now for 9yrs.
If it makes a difference, Im running a -8 feed from the tank to the rail, venom rail, -8 from rail to fpr, and 3/8" hard line for return. This is nothing new either. Its had the same feed, rail, and return for 2yrs now. Same fpr that has been on the car for 5yrs. Only thing that has changes as far as the fuel system is concerned is that I went from 780cc injectors to 1150cc injectors. And yes, my fuel filter is clean.

Time for a bosch 044 inline my friend! Or replace the intank with one.

James

 

[92awddsm]

Time for a bosch 044 inline my friend! Or replace the intank with one.

James

I was thinking more along the lines of an 044 inline and a new 255 intank to feed it. I was planning 044 inline regardless but I am starting to question my 255 due to its age. I had a new spare 255 but it was dropped and the outlet was broken off of it. I was also hoping to get some replies of others having the same or similar issues as me in close to the same power range as me.

 

[VETTE_50_TH]

I was thinking more along the lines of an 044 inline and a new 255 intank to feed it. I was planning 044 inline regardless but I am starting to question my 255 due to its age. I had a new spare 255 but it was dropped and the outlet was broken off of it. I was also hoping to get some replies of others having the same or similar issues as me in close to the same power range as me.

I know i suck at life. Sorry.

James

 

[->PrOjEcTGS<-]

We just installed an intank 044 and an inline 044 w/-8 feed line and a -6 return on Whophlungpoo's car. Needless to say it's a kickass setup!!

Wow similar story. We were about to install his 255 back in with a -8 feed line and he handed me the pump and sender together. Me thinking the pump was mounted only grabbed the sender and the pump fell, breaking off the nipple! Doh!!

He said: "Don't worry, I'm not mad, it's just a reason for me to order another 044 for in the tank!"

 

[92awddsm]

We just installed an intank 044 and an inline 044 w/-8 feed line and a -6 return on Whophlungpoo's car. Needless to say it's a kickass setup!!

Wow similar story. We were about to install his 255 back in with a -8 feed line and he handed me the pump and sender together. Me thinking the pump was mounted only grabbed the sender and the pump fell, breaking off the nipple! Doh!!

He said: "Don't worry, I'm not mad, it's just a reason for me to order another 044 for in the tank!"

Sweet. But this also gives me the opportunity to see if I can machine the plastic top to accept a 1/8npt to -6an fitting. If so and it is successful, It will make for a better, leak free setup.

 

[->PrOjEcTGS<-]

Good luck I don't forsee the plastic holding up too well. But if you figure it out, please post a How-To article on it. I'd be interested in fixing the one he's got and throwing it in my car.

 

[me612]

As the title states, when is an upgrade from a single walbro 255hp needed.

When you attempt to add more fuel, your inj duty cycle goes up, but your AFR's don't change, then that may be a sign you need to upgrade

 

[Savage Talon]

I think the cracking pressure is 60psi on a Wally. You could try modding the pump so it does not bleed off the pressure.

 

[Gamble97]

I think you should lower the pressure on your fpr to like 30psi so it's not working as hard. Plus having an 8an line on a single 255 isn't helping. It has to work harder than it normally would to on a 6an line.

 

[99gst_racer]

How old is your Wally pump, Keith?

I drove on mine for six years before it took a dump (which was last week, btw). I demanded as much as 75 psi (43 base, 32 boost) from it and it had worked flawlessly. I had disconnected my fuel line going from the rail to the regulator to drain the fuel from the tank that sat all winter. With the pump on, every few seconds, it would push a pocket of air through the line. It was completely inconsistent and it was weird that it was only functioning partially. I imagine that if I didn't catch the problem when I did, it could have made a later diagnosis a huge pain in the ass.

Maybe it's possible that you're experiencing a similar problem. Especially if your pump is as old as mine.

 

[grantman10]

Why not throw a Denso Supra TT fuel pump in there instead of a new wally?

Or better yet a Kyosan modified Denso TT pump. I have been reading about these denso fuel pumps that have been modified by a company called Kyosan from Japan.

I don't know a lot about flow rates but the OEM unmodified Denso pumps provide 290 LPH @ 43 PSI @ 14 V, whereas the Wally 255 provides 264 LPH @ 43 PSI. Thats a 26 LPH difference without modification. The Kyosan modified version of the Denso pump has been stated to flow:

10psi 510lph 7.7amps 14v
20psi 470lph 8.3amps 14v
30psi 430lph 8.9amps 14v
40psi 390lph 9.5amps 14v
50psi 350lph 10.5amps 14v
60psi 305lph 11.5amps 14v
70psi 258lph 12.5amps 14v
80psi 200lph 13.5amps 14v
90psi 140lph 14.2amps 14v

30psi 320lph 7.3amps 12v
40psi 273lph 8.3amps 12v
50psi 225lph 9.3amps 12v
60psi 180lph 10.4amps 12v

Taken from here
.

The OEM denso pumps can be had on eBay for around $130-$150, and the Kyosan Modified ones are on eBay as well for $150. CLicky

This is the route I am going to go with my fuel setup for e85. Im going to see how far this Kyosan pump can really go...

 

[Gamble97]

2 255wally intanks or a 1 wally intake and a 044 inline is the baller route. That is what I'm going with next.

 

[dylnwit]

Im sure. I was able to squeeze 476 out of mine on 110, 455 on pump with the old setup, 11.3-11.7afr, 2-3 counts knock and 23* max timing. Timing curve is close to the same, afr is in the11.0 range, and timing maxes at 20*. Once I get to 25-26psi, afr starts going lean and I feel it starting to surge. Im only seeing around 70%dc on my 1150 injectors before it starts to act stupid. As for airflow, I havent logged it yet. Trying to figure out the problem before I even worry about logging airflow.

I know I am at a good bit lower power level and boost pressure than you are, but I also had a lean/surging issue @wot when I was still on my stock pump. Moved to a 190 and the issue went away. This was on the original pump, so it could have been a tired pump or just not enough for my needs anymore.

My bet would be your running out of pump.

 

[99gst_racer]

I second the Denso Supra pump. I just installed mine last week. It feeds an inline Bosch 044 pump (they are a very loud pair). It was almost a direct replacement for my dead Wally pump too.

You must be logged in to view this image or video.

 

[92awddsm]

How old is your Wally pump, Keith?

I drove on mine for six years before it took a dump (which was last week, btw). I demanded as much as 75 psi (43 base, 32 boost) from it and it had worked flawlessly. I had disconnected my fuel line going from the rail to the regulator to drain the fuel from the tank that sat all winter. With the pump on, every few seconds, it would push a pocket of air through the line. It was completely inconsistent and it was weird that it was only functioning partially. I imagine that if I didn't catch the problem when I did, it could have made a later diagnosis a huge pain in the ass.

Maybe it's possible that you're experiencing a similar problem. Especially if your pump is as old as mine.

Dont laugh, but its almost 9yrs old. Im sure it is tired and needs to be replaced but why not just upgrade at the same time? It just seemed a coincidence that it happened at the same time as the upgrades, but at the same time, totally understandable.

I have noticed some weird noises coming from the pump when I let off of the gas and hit the clutch but I was thinking it was the output of the alternator falling off and the pump slowing down. It changes pitch right when the rpm's dropped to 1100.


And the -8 feed line has been on for almost 3 yrs. Never has it been a problem before with the same 255.

 

[gixrman]

I just wanted to add have you checked your voltage to the pump? I was having tuning issues this last week and after checking everything it turned out to my alternator was only supplying 11.5v which was not keeping my fuel pressure up under boost.

 

[1sick91tsi]

Single intank 255 re-wired with meth injection here. Car put down 574whp 464wtq. afrs in the 10.5-10.7 never going lean. Stock regulator and a new fuel filter.

 

[1fastlaser]

Have you replaced the filter on the end of the pump? If thats old id replace it, because it will definatly limit the pump, I had an issue with that before. Noticed the pump got alittle louder all of a sudden. Car was leaning out bad. Swapped it out and was good to go.

Also lowering the fp should help alot, try going to 30psi. But another pump put on duty would probably be the best bet.

 

[99gst_racer]

Dont laugh, but its almost 9yrs old. Im sure it is tired and needs to be replaced but why not just upgrade at the same time? It just seemed a coincidence that it happened at the same time as the upgrades, but at the same time, totally understandable.

I have noticed some weird noises coming from the pump when I let off of the gas and hit the clutch but I was thinking it was the output of the alternator falling off and the pump slowing down. It changes pitch right when the rpm's dropped to 1100.


And the -8 feed line has been on for almost 3 yrs. Never has it been a problem before with the same 255.

Coincidentily, mine died as soon as I rewired it and added the second pump. Go figure.

I thought I did good getting mine to last for 6 years - 9 years is a good life for a fuel pump. Sounds like it might be time for a new one, ehh?

 

[92awddsm]

I just wanted to add have you checked your voltage to the pump? I was having tuning issues this last week and after checking everything it turned out to my alternator was only supplying 11.5v which was not keeping my fuel pressure up under boost.

Voltage to the pump is 13.8v at wot. Idle is 12.7v.

Single intank 255 re-wired with meth injection here. Car put down 574whp 464wtq. afrs in the 10.5-10.7 never going lean. Stock regulator and a new fuel filter.

I dont have meth injection as a buffer.

Have you replaced the filter on the end of the pump? If thats old id replace it, because it will definatly limit the pump, I had an issue with that before. Noticed the pump got alittle louder all of a sudden. Car was leaning out bad. Swapped it out and was good to go.



Also lowering the fp should help alot, try going to 30psi. But another pump put on duty would probably be the best bet.

Pickup filter currently is what came from my new, broken 255.

Im not going any lower than 35psi fuel pressure for atomization purposes with 1150cc injectors.

Coincidentily, mine died as soon as I rewired it and added the second pump. Go figure.

I thought I did good getting mine to last for 6 years - 9 years is a good life for a fuel pump. Sounds like it might be time for a new one, ehh?

Sounds like a safe investment, got any deals for me???