In 2011, I had wrote up an article describing a fuel system upgrade. Here it is, almost 2 years later with no progress. Actually, I had thought I lost the article and wasn’t ready to redo the whole thing again. This morning I happened to find it, and now…. it’s being added so that it will never be lost. At the time I wrote the article I still had the 1.8L 4g37 installed and had hoped to do this procedure before the 4G37 -> 4G63N/T Conversion, which would had eased a bit of the head aches. Also, during the whole “Out of Time” break down, these add on’s would had been very helpful to verify fuel pressure and delivery. Lessons learned, right? This procedure is compatible with all versions and variations of the motors in the 1G DSM’s. Enjoy.
The most pressing reason to perform such a large upgrade is simply the availability of fuel on the last injector. The fuel system is like a sprinkler system, it is under pressure at all times. With that metaphor in mind, a simple sprinkler system tends to have a weak distribution at the last sprinkler on the line due to the weakening pressure on the line. It’s not possible to resolve this by just replacing one standalone part.
Starting at the fuel pump, the highly recommended Walbro 190 is a suitable and compatible replacement for the 4g37, needing only an aftermarket fuel pressure regulator to maintain the correct pressure on the fuel lines. It’s recommended that this pump is used on the 4g36Turbo as well or even the Walbro 255 if running more than stock PSI. This is the first step to make sure that not only more pressure is available at the pump, but more volume is available to the motor.
The higher volume will not be possible if the small diameter fuel lines are still used for this, they will have to be upgraded. For this, I’ve decided to go with -6 Stainless Steel Braided hose. The larger diameter will allow for more flow to and from the engine and will allow us to go from the OEM clamps and barb fittings to aluminum threaded fittings for most things.
A note about installing the pump, to have it compatible with the AN fittings later used, you will have to modify the sending unit in the tank. This can be in a few different ways, but take great caution to not destroy the fragile metal tubes on the sending unit. They are a pain in the ass to work around, but even more so to replace. Below is an image to help you get an idea of what we’re going for.