High fuel pressure at idle
06-14-2004, 01:12 PM
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Car: 94 Z28, 92 s10 Jimmy 350 CID TBI soon to be Vortec TBI, 76 Pontiac Ventura LO3/4L60
Engine: Mega HP!
Transmission: 4L60
High fuel pressure at idle
I have a 1976 Pontiac Ventura. I swapped in a 1992 LO3 and 4L60 from a wrecked 92 Camaro.
Recently I put a 96 LT1 cam into the LO3 engine. At the same time I had a custom chip made for this swap by TBIChips.
The car runs good but I checked the BLM's with winaldl before and after the swap, and the BLM,s are in the 90'S below 2000 RPM and low throttle with the new chip. Before the swap and with the stock chip BLM's were around 110 below 2000 rpm and 120's elsware.
The Ventura has three lines going to the gas tank. 3/8 for fuel, 5/16 for vapor to the charcoal canister, and 1/4 for fuel return these are the stock fuel lines. Iam using the 1/4 for fuel return. My fuel pressure is around 18-20 PSI at idle. I am guessing this is from the 1/4 return line causing a restriction. I am using a holley inline fuel pump 67 gph.
So my question is:
1. Should I use the vapor line as a return line?
2. Put in a bigger return line? I dont really want to do this because i will have to take out the tank and get new fittings put on someware.
3. Get the chip tuned for the higher pressure at lower speeds if this is even possible.
-
--Rod-
Recently I put a 96 LT1 cam into the LO3 engine. At the same time I had a custom chip made for this swap by TBIChips.
The car runs good but I checked the BLM's with winaldl before and after the swap, and the BLM,s are in the 90'S below 2000 RPM and low throttle with the new chip. Before the swap and with the stock chip BLM's were around 110 below 2000 rpm and 120's elsware.
The Ventura has three lines going to the gas tank. 3/8 for fuel, 5/16 for vapor to the charcoal canister, and 1/4 for fuel return these are the stock fuel lines. Iam using the 1/4 for fuel return. My fuel pressure is around 18-20 PSI at idle. I am guessing this is from the 1/4 return line causing a restriction. I am using a holley inline fuel pump 67 gph.
So my question is:
1. Should I use the vapor line as a return line?
2. Put in a bigger return line? I dont really want to do this because i will have to take out the tank and get new fittings put on someware.
3. Get the chip tuned for the higher pressure at lower speeds if this is even possible.
-
--Rod-
06-14-2004, 01:21 PM
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Car: 91 Camaro RS Convertible
Engine: 305 TBI
Transmission: 5-Speed
Axle/Gears: 3.42
Tell the guy at tbichips what your fuel pressure is and what injectors you're running. Then send him the datalogs of your BLM's and everything else and have him burn you a new chip based on that.
Did you set the fuel pressure at that pressure or did it just go there because of a smaller return line? You may want to do what you suggested, changing the line, as well as get a new chip based on datalogs. You shouldn't need to run that high of fuel pressure. I'd say more like 15 psi would be sufficient.
Did you set the fuel pressure at that pressure or did it just go there because of a smaller return line? You may want to do what you suggested, changing the line, as well as get a new chip based on datalogs. You shouldn't need to run that high of fuel pressure. I'd say more like 15 psi would be sufficient.
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