The wiring of the 98 GMFSCI was not a real easy task. Everything had to be done from your back including soldering. Any time you are soldering from your back or upside down, bad things usually happen. I got hit once with a soldering iron and have a scar to show for it. On a good note I was able to avoid solder spatter. The interface mount was fabricated and installed in a different post. So that will not be covered here.

This is the wiring diagram that I worked from. You will also need the fuel pressure module connector pin outs which are located here.

The first thing you need to do is unlock the connector and pull it out. You will need to clean the seal areas and rub on some Vaseline before re-connecting it.

I started out by attacking the easy connections.

Here I am probing for the ignition voltage wire using a volt /ohm meter and some strait pins.

Once located, the connection is made

More and more connections are made and the loose wires have just about disappeared.

Once all the connections are made, plastic wire loom is applied and the end are secured with electrical tape.

It is important to use a quality electrical tape. One that will hold up to temperature and harsh environmental conditions. I suggest Scotch Super Vinyl Electrical Tape 88.

This is a view of the 98 GMFSCI mounted and the wires nicely routed in plastic wire loom.

This is a view of the fuel pressure module connector re-connected and its wires routed.

One thing I noticed was the wire bundle rubbed hard against the pressure module mount. I cut a piece of rubber fuel line and slid it over the edge of the mount.

The next job at hand is to connect switched power to the CNG solenoid mounted at the tanks. Above is a Greenlee Radio chassis punch. I have used these punches since I was a teenager. They will punch a perfectly round hole with no metal disfigurement.
 

Once a pilot hole is drilled, you insert the punch and crank away until you here a tink.

This is what a precision punched hole looks like. I have punched 1/8" aluminum panel with these and had no problems.

A nice rubber grommet is inserted into the hole to protect the incoming power wire..

I am using a two wire connector salvaged from a Cavalier to make a water tight connection. Some zip ties make the job nice and neat.

Unfortunately I had to remove the spare tire. The system GM uses to mount the spare tire stinks. At a later date, I will design a better reusable tire mount instead of the OEM piece of junk.