The Grumpy Grease Monkey mechanical engineer.
rpol98;3433754 said:I wanted to install a mechanical fuel pressure gauge on my 91 L98 TPI. Sometimes the car don't start (driven infrequently) and I want to know at a glance if I got fuel pressure. I wanted the gauge to be visible from the drivers side, and not interfere with removing the valve covers. ended up with a small sheet-metal bracket attached to the back of the smog pump. Adel clamp to hold the gauge. used -3AN teflon Speed-flex hose (covered with heat shrink). there is ample clearance at the throttle body linkage, doesn't interfere with WOT. I found it easier to run the hose from the fuel rail rearwards towards the distributor, across in front of the distributor and then frontward under the plenum and popping out under the throttle body. the 90* fitting just barely clears the MAP sensor and the vacuum hoses. I raised the MAP sensor by about 1/32" for clearance between the rubber angle hose and the fuel AN fitting, probably gonna go in and fabricate a sheet metal spacer instead of the quick-and-dirty washers. had to go with the non-swivel fitting at the rail, because the AN swivel fitting sticks out a little further. Used the readily available aluminum adapter that goes from the Schrader valve stem to 1/8" NPT (ebay I think), with a 90* -3AN adapter on top of that. had to remove the vacuum nipples from the plenum to thread that AN 90* adapter into the aluminum Schrader adapter. Made very sure that everything is tight, and the hose assembly with the brass ferrules was good. can't have no fuel leaks.
while your at harbor freight buy some O-rings,
they come in handy on hydraulics,
and air conditioners etc.
you can get a decent random assortment, of O-rings,
for less than $60 at HF
and you may be amazed at how often its handy to have around,
if your getting some for the shop inventory
be aware the materials vary,
some are used for oil, fuel,Freon, higher temps etc,
but they are not all interchangeable
on the TPI and LT1 efi and many other EFI intakes,
theres a shrader valve,
that can be easily accessed to check fuel rail pressure,
dealing in facts you verify is always preferable.
leaving a small under hood pressure gauge attached is a potential fuel leak point ,
if its not very carefully installed,
a quick detachable test gauge is something any serious mechanic should have.
and you want a fuel pressure gauge that can read,
in the 15 psi-65 psi range, many fuel pressure gauges max out at 30 psi.
and rev the engine a few times and watch the fuel pressure it should in theory remain in the 38 psi-42 psi range for most TPI and TUNED PORT efi