98 Suburban hard starting.

[CalessaSSracer]

Did all the searches prior to posting this thread.

1998 Gmc Suburban 5.7 4x4 with 120,000 miles.
New fuel pump 2 years ago.
New fuel filter, wires, platinum plugs 2 months ago.
(YES I know! I should have gone with the AC delco's!)
New intake manifold replaced 3 months ago.

Truck is hard starting in the morning, with the A/C on it struggles up hills,
it has started to lose power & hesitates even with the A/C off.

Check engine codes
P0131-Low voltage Oxygen sensor circuit.
P0131- O2 sensor

Both codes show twice.

I have no tools to check fuel pressure.
I no longer hear the fuel pump buzzing.

[777stickman]

Code P0131 referes to the 02 sensor (H02S Bank 1 Sensor1) coming off the left bank manifold before the cat converter. This code can be set by a faulty wiring problem to that sensor indicating a "lean" mixture or the sensor is correctly indicating a lean mixture from a vacuum leak or a fuel control system problem.

1st thing is to get the fuel pressure tested and kind of go from there since you don't hear the pump running. Is that replacement pump an AC Delco? If not and it turns out to be the pump again I would do an AC Delco.

Let us know.............Steve

[CalessaSSracer]

Thanks Steve, the pump was "Master".
Stealership wants $550 for A/C Delco fuel pump.
Diagnosed the problem it's the fuel pump. Went to my buddys shop, yes i get to play with his tools.
LOW pressure.

Guess what?
Saturday I just happened to put 25 gallons in the SUB.

Draining 20 gallons.


Dropping the tank.

I'm back on the road!

[777stickman]

I'm on the road and this is probably too late, but if you can find an AC-Delco parts store nearby you can probably save some $$'s over the dealer's price. Another thought is the fuel filter?? Thanks for posting back and great pic's ......Steve