DeanJ

Got a custom tune and some dyno time this past friday. Me and Alvin rode around most of the morning while he tuned on my car . It runs and drives really great now. So we go back to his shop, (PCMforless). He backs her up on the dyno, and makes a pull. He shuts it off early, went lean, made 367 HP. Makes a few changes, starts up again And this time I watch the fuel pressure guage, it's mounted on the regulator at the fuel rail so you can't see it while driving,I'm going to remedy that later.He starts the second pull, As the rpm's come up pretty good the fuel pressure starts to fall. Just as I was about to yell, he shuts it down. Went lean again. The bad news is my fuel pump wont keep up. The good news is it that it made 401 HP & 391 torque @5500 rpm's. He says my cam should be good to about 6100 to 6200. I can't wait to go back with a better pump. I have another dyno appointment July 9. I can't wait, Dean

AmorgetRS

iTrader: (6)

What fuel pump are you running? Just a stock one?

DeanJ

It's a Racetronix/Walbro that's only 1 month old. I hate changing fuel pumps on this thing. I'm going back with a (sigh) Toyota pump.

AmorgetRS

iTrader: (6)

Huh, I've never heard of using a Toyota fuel pump for more flow. I am guessing you used a Walboro 255 w/ the Racetronix wiring kit?

DeanJ

Yes it's the 255. I made my own hot wire kit. I have an 8ga wire from the back of the alternator to a relay at the fuel tank. It's basically a copy of a hot wire kit, with a larger main wire. From what I've been reading, the Denso 1020 is a bad boy! Dean

one92rs

iTrader: (5)

here are some info on pumps. couldnt help it i love researching stuff. take a look.

http://www.stealth316.com/2-fuelpumpguide.htm

oh yeah is this the hotwire harness you made?

http://www.racetronix.com/RX-G7-FPWHG.html

Jim85IROC

iTrader: (2)

A single Walbro 255 is supposed to be able to supply sufficient fuel for somewhere around 600RWHP or more. I'd be taking a look at the rest of your fuel system, not just the pump.

AmorgetRS

iTrader: (6)

I have a Walbro 255 and a hotwire kit feeding my Turbo 00 Trans Am, so I'd look at things other then the fuel pump, too.

DeanJ

92, that's a good read, thanks. Here's what my fuel system consists of. It has the stock 3/8" feed line going to the front of the right fuel rail, a crossover at the rear of the rails, a Fuel Lab regulator mounted directly to the front of the left rail, then a return to the stock 5/16" line back to the tank. It also has a stock replacement Wix fuel filter that was installed when I installed the pump, about 5 weeks ago. Could the filter be my problem? Not large enough? Is the 3/8" feed line not large enough? The Walbro is also now making a little more noise than when I installed it. Any ideas guys? thanks, Dean.

DeanJ

Here's some pics, if that will help. All of the braided hose is #6

bad86z28

iTrader: (1)

Doesn't seem like there is anything wrong with your fuel setup. I basically had the same thing on my '86 and it was good to 420 hp. I actually ran out of injector but the Walbro pump was still up to the task. Only difference was that I used '98 Corvette fuel rails with the built in regulator. I would take a close look at the fuel filter as it seems like it would be the only questionable piece in your setup.

one92rs

iTrader: (5)

now when i was in the ls series engine game i seen many people push in the 5 and 600 hp applications with a single walbro pump. what psi are you running. is the tune absolutely correct. is the maf table and ve tables absolutely correct. this will all have a part in the fueling. a regulator problem or a restriction could be the cause. you could be looking at the injectors as well and the duty cycle set up in the pcm/does the pressure fall off or just the engine going lean.

DeanJ

Fuel pressure falls from 60lbs to 40lbs around 5500 causing the lean condition, simply not enough fuel therefore we stopped the dyno session. Everything looked pretty good till then. I think I'll look into a larger filter. Anyone have suggestions? The filter needs to have #6 AN or pipe inlet & outlet. Thanks to all, Dean

one92rs

iTrader: (5)

kinda weird. i have personally used with nos above 500hp with no problems at all. maybe u gotta bad one.

DeanJ

The noise the pump makes seems to be getting a little louder day by day. It also has changed from a high pitched hum to a lower kind of growl. I think it's maybe taking a dump. I'm going to change it this weekend regardless. Dean

DeanJ

The harness and relay setup I made is a dead copy of this, with one difference. The main power wire from the back of the alternator is 8ga.

88 350 tpi formula

iTrader: (9)

since your pump is making more noise im thinking a pick up sock issue.. dirt or sucking shut some how

Iroc-N-Rollz!

iTrader: (2)

Im going to go with this as well..

$750 L98

I had a 255 that was doing this as well, the pump had sucked up trashed and began to make a slow growl rather than a higher pitched whine when running. Sounds like a bad pump.

DeanJ

Thanks for all the replies. After much research, I have found a little more than normal failure rate with the Walbro. The Denso/Toyota pump seems to be way more reliable, and by all reports, flows more at the same psi. I'm going with the Denso, maybe two if I can fit them in the tank. I'll let you know how it goes. Dean

DeanJ

All parts associated were new (pump sock wiring ect.) I looked at the inside of the tank, the best I could and it looked OK to me. I hate doing things twice, but looks like it's necessary. Dean

cam-

Denso makes good stuff. Their injectors are kick *** too

DeanJ

Hi all, I installed the Denso pump today.This thing runs absolutely silent. I couldn't even here it prime. Almost thought I'd done something wrong. I have another dyno appointment July 9. I'll let yall know how it goes. Dean.

DeanJ

Hi guys, the dyno session went well this morning. The Toyoya/ Denso worked great, 60lbs of fuel pressure all the way to 6600 rpms, nary a wigglle of the gauge. Made 420 rwhp, here's the best part, 397ft lbs peak torque! It has 325 ft lbs torque at 2000 and continued to clime to the peak at 5400. Peak hp was from 5600 to 6400, hp hardly changed in this range. I highly recomend the Denso pump. And a big thanks to Alvin & Kelly at PCMforless. And thanks for all the info I've gotten here on thirdgen.org. I'm a happy boy, Dean.

one92rs

iTrader: (5)

those are some nice numbers.

1989GTATransAm

iTrader: (3)

Wow, those are some good numbers. Any plans on taking it to the track?

DeanJ

Yes. I went to Z-Max Dragway, on street night about a month ago, before the tune. Went 13.65@112, traction was a rumor at that place. 2.57 60 ft time was the best I could get. I'm sure the Kumo street tires didn't help either. Scared to put any stickies on the rear, I'm sure the 10-bolt wouldn't last long LOL. I just started building a jig for a 9-inch ford housing. I'll put some drag radials or slicks on then and see what it'll do. Maybe some 3:70 gears too. I was very pleased with those numbers. Alvin @ PCMforless is the man. I'll update when I get back to the track. Later, Dean.