Fmu Question

tcavenger99 · 06-11-2008, 07:49 PM

OK when installing fmu can it be mounted under the hood. If the answer is yes what lines should i use . plus do i have to remove the vac line of the oem fuel regulator once the new fmu is installed .

Locke · 06-11-2008, 08:06 PM

The FMU has to be installed into the regulators return. Your '98 has the late model fuel system, a "returnless" fuel system. The FPR and it's return is located in the rear of the vehicle, just in front of the fuel tank. To keep this configuration and have the FMU mounted under the hood, the return line would have to be extended into the engine bay, where the FMU is, then back to the tank.

Most people who intend to mount the FMU in the engine bay will convert to an early style fuel system, a conventional fuel system whose regulator is affixed to the fuel rail. All you need for this is a '95-'96 fuel rail with FPR and some plumbing.

Your FPR doesn't doesn't have a vacuum line.

tcavenger99 · 06-12-2008, 07:26 AM

ok thats all ok . See when i blew the motor years ago they replaced it with one out of a 98 , yet my fuel rail still has the regulator built into the fuel rail ??? so now what do i do with my fuu.

totaleclipse_05 · 06-12-2008, 07:38 AM

Hook it up the way the 95-style fuel system is setup then.

tcavenger99 · 06-12-2008, 01:19 PM

so the stock one attaches to the fuel rail how am i suposed to by pass that with the new fmu. sorry about all the dumb questions

Locke · 06-12-2008, 02:26 PM

Leave the FPR alone - install the FMU into the return line coming out of the fuel rail.

tcavenger99 · 06-12-2008, 03:56 PM

ok so let me get this stright i should install the fmu on the other end . The side closest to the battery and then just tee into the the system (right)
one last question at idle my boost gauge reads 15vac if i tap the gas it goes to 10 vac
does this sound normal ?

Locke · 06-12-2008, 05:19 PM

Here is one of Paul's handy-dandy diagrams.

Vacuum will decrease with an open throttle.

tcavenger99 · 06-12-2008, 06:06 PM

wow thanks last question do i leave vac line connected to oem fpr my system i have the early 95 -96 system

tcavenger99 · 06-12-2008, 06:08 PM

o yea 1 last thing if u tighten the fmu nut does it incerss or decress the preasure my fmu has no instructions