I have an 88 turbo with RB exhaust, RB FCD, Bonex intake, and Hallman manual Boost controller, and have been emailing back and forth with a guy at Rx7.com on which pump would be a better choice for the 2nd gen. A Walbro 255 lph pump vs a used 3rd gen stock pump.

The guy at Rx7.com says;
"I can tell you from real world dyno experience, that the Walboro fuel pump cannot keep up with the stock 3rd
gen fuel pump and is going to be lucky against the stock second gen fuel pump. If I remember right, they account for peak pressure and peak flow volume(which is at peak pressure). What is important, is constant pressure
and constant volume, in a particular application. In the RX-7, we have found over and over again, that the Walboro pump is a very bad idea. I will dispute this on the Dyno with any Walboro representative, not in test facility under ideal conditions meeting specific goals. Trust me, if the Walboro pump was worth anything, we would sell it. It is easy to get and cheap to buy"

Help please?

 

Sounds like he has put some time into his conclusion about the 255, although he hasnt figured in the age of an FD pump, 10 years old. you may want to think about this before your purchase. I would assume that the 255 would be more than enough for your power output, and would take you to 450 safely at the crank.

 

I don't know about 450 at the crank, since i just witnessed a FC that couldn't break 348 RWHP with a T66. Kept running out of fuel, but the fuel system was completely done. The tuner ( a very reputable one) doesn't like them, for that same reason. If your goal is under 300 WHP then go for it, but don't count more than that.

 

A friend of mine blew 2 engines on his setup. Sold me all his aftermarket parts and i blew mine also. These were both FDs These were all caused by severe spiking due to a midpipe i believe. When i had my Mazda reman installed i had the Walbro 255lph installed and an SX fuel pressure regulator. I've spiked severely quite a few times since then and have yet to blow my engine. Not sure if the regulator or the pump has saved it though. I'm running 14.5 lbs boost with spikes over 18psi with the Pettit/M2/Gforce ECU which is supposed to only provide fuel for 14.7?+- lbs of boost i believe. I'm running stock turbos with pretty much every bolt on.

 

I know the supra TT, as well as skyline GTR pumps are a popular upgrades for DSM guys. Does anyone have one on their 7?

 

Well.....FYI:

I'm running a Walbro high presure 255 (Gss341 or 342) and I've layed down 402 rwh with A/F's in the 10's and now with ported motor I've decided to drop a fuel pressure gauge to monitor fuel pressure and I have yet to see it drop !!!!
The Walbro will easily hold 450 wheel hp !!!

Later

 

I also installed a fuel pressure gauge and can see that the Walbro is holding pressure nicely at full thottle on my 2ng gen.(around 55psi) I also checked the voltage at the pump and it looked good at 13.4 vdc.

So far so good with the Walbro 255 lph, but I've only had it in for a week. It was a breeze to install also.

 

Mine began crapping out. It has ~15K miles on it, & I always ran 14 PSI or less boost. I think one of the causes for the premature failure was that it was pushing fuel through a very restrictive K&N fuel filter.

I'm trying out all Aeromotive stuff this time with top feed rails.

 

What are the symptoms your having to definatly know its the fuel pump?

Also as a side note, I've been making over 400rwhp and 18psi of boost for quite some time now on the high flow intake Walbro. HOWEVER, they do make 2 models, they are both 255 I think but one is a higher pressure.

I think the key to getting good fuel delivery with a Walbro is to keep the pressure as low as possible. The higher you jack the pressure the less fuel your going to get. I'm running the stock fpr.

 

On the dyno my A/F was safe up to 6K RPMs. At that point they would climb to the mid 12's. I cranked up the fuel multiplication map by 10%, & the A/Fs went to mid 13s! This would lead one to believe the pump can't support the demand dropping the rail pressure...

I had the GSS341 high flow/high pressure. Boost was 14PSI with the stock FPR. I also started noticing a fluctuating idle. When I monitored the pump voltage it was correct, but would fluctuate with the idle. This lead to my believing the pump could no longer supply a consistent flow or maintain consistent pressure. I've since thrown the same pump into an LS1 FD & saw basically the same results.

In the pumps defense I was using a crappy in-line K&N fuel filter which was most likely making the pressure at the outlet of the pump MUCH higher than it should have been to sustain the desired rail pressure.

I figured I'd be better off to upgrade it all. Better safe then to pick pieces of ceramic apex seals from the turbine blades of a GT3540...

 

Yea, trashing an engine is no fun haha

I'd agree its probably the restrictive filter making your pump have to work at much higher pressure levels to keep the rail pressure up. The Walbro can flow a lot of fuel but it doesnt really like high pressure

Course did the LS1 have the same restrictive fuel filter? I cant imagine the pump not producing enought pressure for a N/A LS1.....or was it forced induction?

STEPHEN

 

The LS1 FD was using a stock Mazda fuel filter. The pressure gauge was bouncing between 20PSI & 40PSI. The stock Denso pump was holding consistant 30PSI.

Like I said I'm pretty sure the Walbro has had it.

I wired up the Aeromotive last night, & only had one fuel leak. Pressure was solid at 41PSI.

I may be able to crank it tonight.

 

I think all you guys need to get serious and step up to the Berry grant Sumo pump. That pumps like 300 GPH, They sell them in summit racing. The berry grants range from like 200 bux up to like 500. but i think it would almost be worth it, just to know that you will always have enoug fuel.

CJG

 

Sorry for the OT post, I just stumbled upon this while researching a problem for a buddy.

You may already know this, but LS1's run 4 BAR (58 PSI) at the rail. Hate to see you chasing a ghost of a problem that is simply low fuel pressure.

Chris