FullBlown

iTrader: (7)

I get alot of people who ask me how to modify a walbro fuel pump to hold pressure. There are alot of guys now that are running their dual pumps past 75psi since they are running 40+psi of boost. Well heres the story on how I accidently found out how the modified ones work.

Back last year when I sent our Dual Pump setup in to RC ENG to get flowed, I got the flow chart back and it said on the bottom of the page that the "Bypass Valve opens at 75 psi" When I saw that I was like wtf!! So I went and found the flow chart for the "Modified Walbro" and what do ya know.. at 70-75 psi the modified walbro kicks the non modified's ***. At that point I knew that the bypass was the only reason why the modified walbros outflowed the non, but i never got around to messing wit it.

Then, about 6 months ago I got in a shipment of walbros and 2 of them were damaged and UPS was being ****** about it so I just decided to keep it incase i needed them to mock up any new projects. Well.. today i was at work and just just got done wrapping up a customers car and had some free time to play with the pumps. Here is what I found.. I suck at explaining things so Ill let the pictures help.


WARNING!! I DO NOT RECOMMEND THIS MOD, WALBRO WILL VOID THE WARRANTY OF YOUR PUMP FOR SURE IF YOU DO THIS TO THE PUMP. THERE IS A REASON WHY WALBRO CHOSE TO PUT IN A RELIEF VALVE. PLEASE DO THIS AT YOUR OWN RISK

Here is a ghetto drawing of a non modified walbro ( i know i spelled hole wrong)



Heres the pump all take apart


Here is a shot of the bottom of the bypass valve


Heres a shot of the top


Befor we go on please be careful and wear goggles and a pair of gloves. You might want to have a friend help you.

Take a punch, I forgot the size of the punch but just size one up that fits and line it up and give it a few good wacks jk all you need to do is tap it a few times until it bottoms out.



BAM!!! Thats it youre all done, now go have a and paypal donations to Fullblown@tmail.com

Here is a drawing of the modified walbro and befor and after pics of the plug


Before


After

Paul Nelson

iTrader: (1)

Nice LJ . I wish i would have known about this before i went to a different systems

FullBlown

iTrader: (7)

Yeh it woulda been interesting to see how far we could of pushed 2 of these modified pumps.

Evoryder

iTrader: (55)

cool...only 16psi more to go for me to need this mod.

SlowCar

iTrader: (4)

screw gas, put in 2 more methanol nozzles

Sean@Iveytune

iTrader: (14)

This is a very interesting thread. Very interesting.

Sean

mitsuorder

iTrader: (106)

Don't take this the wrong way but didn't Walbro themselves warn about the reliability of the pumps if this modification was done?

AlwaysinBoost

iTrader: (17)

this is great info, thanks.

Because of what you posted I'll be buying your double pumper setup shortly, instead of using another vendors setup.

CharlesJ

iTrader: (6)

Moved this to How To and edited a bit to keep it on topic. Please DO NOT use this thread as a means to discuss other matters that have already been discussed.

whitepwr

iTrader: (6)

Anyone know how far a modified 255 Walbro can be taken to on E85?

jason900rr

anyone even done this mod????

INEVOIX

I can only speak for my set-up. It may be different for yours.
I've been running the modified pump since last year.
On E85 with PTE 1200 injectors, I can run 30 lbs of boost. That is pushing it!
This is with a stock block, stock cams and a 35R kit.

PlanoEvo

iTrader: (2)

I've searched and cannot find this modded flow chart?

C130flyer

iTrader: (8)

I modded my pump like this to cure the lean spike while runnin 30+psi and it killed the pump after 5000 miles lol

Colt4g63

iTrader: (8)

I dont think this mod killed your pump.... Been running on walbro 255s pump with this done for 20k miles now.