DIAGNOSIS:
Replacing a bad fuel pump
PROCEDURES:
Disconnect battery
Remove the lid on the rear deck of the car. Remove the
fuel filler cap. Slide the rubber boot over the fuel filler
neck. Be careful not to tear the boot. Remove the 10 or 12
bolts that attach the fuel filler neck to the tank.
Grab the fuel filler neck and carefully twist and lift
the pumps out of the tank. The pumps are all attached to the
fuel filler. Be careful not to bend the rod on the float for
the fuel filler gauge. Make sure to install new fuel
strainers on bottom of pumps.
When you remove the old pumps from the module, and
install the new pumps make sure you use new clamps and that
all of the rubber hoses that connect to the fuel pumps are
in good shape and be careful not to crimp any of the hoses
that would restrict fuel flow. Also get an ohm meter and
check the resistance on all of the wire connections to make
sure the pumps are getting current.
When re-installing you have to carefully twist and turn
to get the pumps and the pump housing installed back into
the tank. Once you get everything in the tank firmly push
down to seat the fuel strainers on the bottom of the tank.
make sure to use a new gasket where the fuel filler neck
bolts to the tank and tighten it up.
Did not notice any fuel mileage degradation cruising
around. Noticed a big difference running balls out.
However I had a weak secondary pump to start with.
Once you get it back together do a fuel pressure check as
follows:
1. Remove primary pump fuse on side passenger side panel.
Attach fuel pressure gauge. Turn ignition on (but don't
start motor) this tests the secondary pump. You should have
about 50 to 60 psi. Before I replaced the pumps I only had
38 lbs on this pump. After replacing the pump I had about 55
lbs of pressure.
2. Bleed off pressure from gauge. Reinstall primary pump
fuse. Remove secondary pump fuse. This is under the
passenger side of the dash board. It is a bitch to get at.
Read the owners manual for more details on this fuse. Do the
process I mention above to test the primary pump now. Before
I replaced the pump I had 45 lbs, now this pump has 55 lbs
as well.
Last change the fuel filter. It is on the underside of
passenger side of car.
With engine running fuel pressure should be at or around
42 to 50 psi.
Fuel Pump part numbers:
GM Part #25163473 ($72) *Fits '96 Suburban with 454
Engine
Airtex - E3904 ($69) (800 424 7839)
Master- E3265 ($69)
Neihoff - P36 (it also has BWD P36 on it) ($65)
I would recommend the Master brand over the Airtex but if
you can get the Neihoff do that. It's internal parts are all
metal. The Airtex one failed on me a month after putting it
in. It also has a wiring harness change over you have to do.
The Master and Neihoff are a drop in replacements.
As per Scott Fabre
Also note you can buy fuel pumps at most auto parts store
like Autozone which sells them for $50-$65. The part number
is 3940 however the 3904 has a different electrical
connector than the original pump. You can use the 3265 which
is the replacement for the LT1 engine, but it has the same
connector as the original LT5 pump. They also have the sock
filters as well. They are made by airtech. Airtech supplies
them for GM and GM stamps their own delco logo and part
number on them. You can also use 3270 part number as well.
