RE:CAR GOES LEAN AT 5000rpm

1hawaii50 · 08-17-2003, 10:51 AM

I just picked my car up from a "dyno tuner" after they had it for 6 1/2 weeks, and it cost me $1,600.00 and change, and they still can't tell me what the problem is. I won't name the shop, because I don't want to start a flame session, more importantly I need to figure out the problem. At 5,000rpm on the dyno, the engine goes lean. Adding more fuel into the motor via a flash chip doesn't help. They dialed up 65psi of fuel pressure, and the pressure held, but the motor still went lean. They replaced the in-line pump, saying it was bad, but the problem didn't change. I have a 1992 GT w/ a DSS 306, Edelbrock heads/intake, 1.7rr, Anderson B-21 cam, 42# injectors, MSD ignition/coil, plugs 2 heat ranges colder than stock, 70mm throttle body, Vortech S-trim w/Aftercooler, no FMU, Walbro 255 (high pressure)in-tank pump, Walbro 255 in-line pump, new fuel filter, and Pro-M 80mm mass air. The fuel lines/rails are stock. I'm wondering if I'm maxing out the injectors? The stock rails should be good to 550-600rwhp. My other thought is I may have a wiring problem with the in-line pump, and voltage may be dropping at the pump, causing it to lose volume. If anyone has any ideas, I sure would appreciate it!

Agent_4573 · 08-17-2003, 02:29 PM

your not maxing out your injectors but i dont know about the rails.

bottlebaby91 · 08-17-2003, 05:58 PM

Definatly sounds like a fuel delivery problem, I would check pumps to make sure one isnt dying out.

08-17-2003, 10:51 AM	#1
1hawaii50 Registered Member Join Date: Sep 2001 Location: Brook Park, Ohio, USA Posts: 1	RE:CAR GOES LEAN AT 5000rpm I just picked my car up from a "dyno tuner" after they had it for 6 1/2 weeks, and it cost me $1,600.00 and change, and they still can't tell me what the problem is. I won't name the shop, because I don't want to start a flame session, more importantly I need to figure out the problem. At 5,000rpm on the dyno, the engine goes lean. Adding more fuel into the motor via a flash chip doesn't help. They dialed up 65psi of fuel pressure, and the pressure held, but the motor still went lean. They replaced the in-line pump, saying it was bad, but the problem didn't change. I have a 1992 GT w/ a DSS 306, Edelbrock heads/intake, 1.7rr, Anderson B-21 cam, 42# injectors, MSD ignition/coil, plugs 2 heat ranges colder than stock, 70mm throttle body, Vortech S-trim w/Aftercooler, no FMU, Walbro 255 (high pressure)in-tank pump, Walbro 255 in-line pump, new fuel filter, and Pro-M 80mm mass air. The fuel lines/rails are stock. I'm wondering if I'm maxing out the injectors? The stock rails should be good to 550-600rwhp. My other thought is I may have a wiring problem with the in-line pump, and voltage may be dropping at the pump, causing it to lose volume. If anyone has any ideas, I sure would appreciate it! __________________ 1992 GT w/DSS super-pro 306, Edelbrock heads/intake....I guess it doesn't really matter since I'll Probably be divorced soon, and she'll get the car!!!

08-17-2003, 02:29 PM	#2
Agent_4573 Registered Member Join Date: May 2002 Location: New Jersey Posts: 375	your not maxing out your injectors but i dont know about the rails. __________________ '89 LX 5.0, off-road h pipe, flowmaster muffs, underdrive pulleys, rebuilt WC T-5, King Cobra Clutch, 65mm throttle body, Explorer Upper/GT40 lower, Lakewood Rear Lift Bars. 76mm C&L Mass air w/ inlet pipe, Twisted wedge heads w/ stage 2 port,polish, MAC equal length shorties, Billet AFPR, 255LPH fuel pump, fresh low end w/ 10.5:1 compression. If anyone ever wants to go to Raceway Park in Englishtown New Jersey, give me a shout. RICER HATERS CLUB MEMBER 87! www.ricehatersclub.com

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08-17-2003, 05:58 PM	#3
bottlebaby91 Registered Member Join Date: Nov 2002 Posts: 141	Definatly sounds like a fuel delivery problem, I would check pumps to make sure one isnt dying out.