Fuel lines

[FunkyLT-1Mod]

As my name suggests, I'm doing a very strange mod, and need to know how the fuel system on the F-body works for the LT-1. I'm sure that I will need to duplicate it on the car that I'm currently installing the engine in. I know that I will need to get the fuel pump assembly from a Z28, but is there any other considerations; how many lines go to the gas tank; are there any special breather considerations: etc?

For the Record: I'm installing the engine (1994) in a 1985 Oldsmobile Custom Cruiser after it's carbed engine got a case of death rattle. I got a great deal from Ebay and couldn't pass up the engine, but now it has become a PITA to install due to the changes over the ensuing 9 years. I'm almost there, though!

Your help would be most appreciated.

Ron

[Joe K. 99 Zeee!!]

Custom Cruiser!! Hey, my folks had one of those in station wagon form. It was a '81 or so I believe...big ol V8. Complete with fake wood. Went all over the country in that thing. Lotta Torque, but no acceleration.


I'm at work now so I don't have the site, but it should include a schematic of the fuel system. I can post when I get back home.

[Injuneer]

Fuel pump assembly mounts in tank. Discharge line from pump runs out top of assembly, through fuel filter, to passenger side fuel rail. It is plastic from the tank to the fuel filter on the rear subframe, hardline to the front subframe, and plastic to the intake manifold support bracket on the driver's side corner of the intake manifold. There it attaches to a hardline that attaches to the rear of the passenger side fuel rail. The hardline has a Schrader valve for pressure testing.

Fuel runs down the passenger side rail, across the diagonal pipe at the front of the rail, to the drivers side rail, down to the back of the drivers side rail, where the non-adjustable fuel pressure regulator is bolted to the end of the rail. A hard line connects the FPR to a plastic return line, that duplicates the supply line, although a slightly smaller diameter. Return enters the top of the fuel pump assembly. Fuel pressure is controlled by a spring in the FPR that controls the return of fuel to the tank.

Also on the top of the fuel pump assembly is a vent line. That line goes through a couple valves (you really need a good diagram) to the evaporative emissions canister in the drivers rear fender. From there, a vapor feed line runs from the charcoal canister along with the fuel lines (that's why there are 3 lines in the bundle... feed, return and vent) to the EEC purge valve on a bracket in the middle of the passenger side of the intake manifold. From the solenoid, a vacuum line runs to the passenger side of the throttle body. EEC purge is controlled by the PCM. The fuel system is basically "sealed" and will only vent to atmosphere if the tank is overpressured and the pressure relief valve opens.

The fuel pump is powered of a "fuel pump relay" and that relay is turned on and off by the PCM.

You can find most of the LT1 diagrams on Shoebox's Tech Pages. . Just be careful, becsaue all his stuff is for a 95, and there are a number of differences on the 94. The fuel system and EEC system are the same, however.

Back of intake with fuel lines, FPR and Schrader valve shown. slightly different from stock, since the FPR is adjustable, and the Schrader valve has a -4AN 90-deg elbow screwed on it. Note the vacuum line running from the passenger side of the intake. It belongs on the vacuum compensation port of the FPR, but has fallen off and is laying on the EGR valv

[tabahr]

you'll need 2 lines to the tank and 1 vent tube. The two lines are the supply(larger) and return(smaller). They go to the two connections on the fuel rail. The vent line goes to the solenoid on the pass side of the intake then to the throttle body from there. you may want to leave the gas tank stock and mount a aftermarket fuelpump under your hood and plumb it directly to the input on the fuelrail. The factory gas tank setup would probably be pretty pricey. It will probably be a good idea to replace the fuel filter while you're at it.