popping and busting out above 10 psi

[j5ash]

New engine in car, runs like a champ below 10 psi! Anything above that it seems to busting out. If we spray alky at lower boost (11psi) and max out the pump speed, it will compensate for the problem and run great up to 19-20psi boost. The only changes were LS1 MAF and translator, roller cam and rockers, and 70mm TB and upper plenum. It has the same injectors(009's), turbo(te 60), heads(Champion irons), chip(Red's 93), everything as before. I have tried draining gas and filled up 93 octane Chevron, added a bottle of "Heet" to remove any water. I have also rechecked the cam sensor setting. The fuel pressure has been raised to as much as 43 psi with vac ON, and I am still not seeing more that about 58psi at wot. Could the fuel pump be weak? Any help would be greatly appreciated.

 

[j5ash]

Oh yeah....We have also tried 2 different FPR and changed the fuel filter. Thanks Jason

 

[SouthernCal GN]

How old is the fuel pump? Is it hotwired? When you installed the engine, did you kink/pinch the fuel lines?

 

[j5ash]

Don't think we kinked any fuel lines. My friend and I were trying to decide how long ago on the pump, not exactly sure but several years maybe 3 or more. It's a Walbro 340 and is hotwired.

 

[SouthernCal GN]

Might as well change it out and ensure that's not a part of the problem.

 

[rays87limited]

what kind of press is a walboro 340 cap. of this pump wont go over 60 psi no matter how it is adjusted

 

[Matt McClung]

Just for the heck of it, close the gap on your spark plugs. You may have a weak coilpack and when you make the gaps smaller it is easier for the spark to jump the gap. If this helps, replace your coilpack. I have had this happen before and it was the coilpack causing all of my problems. BTW, Gyrhead and sons are selling coilpacks for $35 for a limited time.

Matt

 

[j5ash]

Matt, I would normally tend to lean that direction but since I can suppliment the fuel with alky and the car runs like crazy I think it's a fueling issue. Thanks though, I won't rule it out. Jason

 

[that guy]

Do you have a fuel gauge that you can check while driving? Hood mount or extension you can see while driving? Might be able to find out what your fuel pressure is doing prior to replacing the pump. The pinched/kinked lines are a great place to start. HTH

 

[Blazer406]

Just a suggestion. Turn the boost back to a safe level with straight pump gas..... now turn the alky kit off. Now see if you make it past 10 psi boost without the bucking/surging/popping. Report Back.

Oh.... what alky kit are you using?

 

[j5ash]

I have tried turning alky off and boost down. Still get the "huck-a-buck" right at the 10psi range. The only way I get it to go away is setting the alky to come on around 10psi and spray wide open, I'll check again for the pinched line. I read another post last night, similar problem, about the hose on pump itself possibly being split. Dazed and confused!!!!!

 

[j5ash]

SMC progressive kit, forgot to add that. Jason

 

[SloGN]

the pressure relief valve in the walbro 307's and the 340's will make 80 psi.

 

[AM86]

Sounds like the prob I had when my MAF went out... I'm still learning so take that for what its worth lol...i'm sure the rest will add or take away any merit to that comment... one other thing do you have a scanmaster??? you might be better off posting the readings your getting when the popping happins

 

[j5ash]

Update**** I found my problem to be something to do with my LS-1 MAF and translator. There is nothing wrong with the parts as we put them on a friends car and they worked flawless, and vice versa his stuff produced the same poor results on my car. I put the stock MAF back on and it runs perfect. Anyone had this problem or know where to go from here? Thanks Jason