I have 30lb SVO injectors on the modded engine in my sig with the STOCK pump with 56K on it.. When I give it slight gas when normally accelerating it will go fine but when I give it about 1/2 throttle it will bog bad. I scanned it and the O2 go lean like to 80mv. I tried bigger pump shots in the chip but no good. I just hooked up a fuel guage on the rail and with the vac line connected its around 36psi. With it disconnected it goes to 41psi. Now with the vac line connected and I rev the motor I see the pressure jump like 1-2psi and then dive to 29-30 psi. Now if I rev it more it will drop further. Does this sound like the stok pump cant handle the 30lb SVO injectors??? I also have idle issues that I cant smooth out......
Thanks!!

 

??

 

It does sound as if you have a fuel delivery problem. That could be the pump (including pump voltage), regulator, filter, and line set.

 

My buddy is running 30# SVOs in his 93 and he couldn't maintain pressure with his stock pump. A new Walbro fixed it. His car still ran fine though, we wouldn't have noticed anything without the gauge.

 

pressure regulator?

 

You're not outrunning the fuel pump revving it in neutral. If you were the car would be pretty much undriveable.

The pressure drop you are seeing as you rev is because when you lift off the throttle you get more vacuum than at idle. Which lowers the fuel pressure.

The only way you can check if you are outrunning the fuel pump is to watch pressure under load.

 

Ditto. I have a buddy with a 383 using 30# injectors and the stock pump could NOT keep up while driving in WOT. Fuel Pressure would drop under 30 psi when in WOT. New high flow fuel pump cured the problem.

30#ers suck a lot of fuel when you start making HP.

 

OK so I dont need a fuel pump...but I might need one at WOT?? But why the bog??? And the O2 drop...I gave it like 3 times the AE but it still goes lean???? to like 80mv

 

Sounds like you need to tweak the AE some more, more duration or something. AE in a MAF car is kind of wacky, more than one table to play with in there.

And you can't take for granted that your sensors are all working 100% either. Sure the TPS is good, no dead spot or anything? Maybe the MAF is slow, since delta LV8 plays a big part in the shot. Although really, the biggest oart of the pump shot is/should be the first. Once you're near half throttle you're flowing most of the air the engine will take so delat LV8 won't do much i would guess.

I tuned a little bit on a bi cammed stealth ram car, but it was SD. Needed a pretty good amount of pumpshot to not bog. Also helps if the BLMs are close and consistent and the boundaries are logical. For example, most stock GM bins have the high BLM rpm threshold at 2k. So 2k+ is all one cell. If you're 108 at 2000, but closer to on by 3k, then if you squeezed the throttle through there you'd end up lean as rpms went up.

Hard to ay more without seeing the car.

 

what would be good to try.... like 28 in the number of accel enrich pulses vs coolant temp and then scale the LV8 accel enrich factor va delta LV8 by 3. What else should I mod??? Please help???

 

You still haven't done the test that you need to do. Don't do anything until you verify your fuel pump is OK. Ed is on the money with his comment about the load.

All you have to do is this...
Hook up your fuel pressure guage and tape it to the windshield. Go do a WOT blast. When you open the throttle from part throttle to full throttle then the pressure should go up. During the entire time at WOT the pressure should NOT come back down. It should only decrease once you get off of it. If your fuel pressure doesn't hold rock steady at WOT then most likely it is your fuel pump. No sense tuning your AE if your fuel pump can't keep up. Do the test first.

Tim