Fuel or Ignition problem?

[Larryv]

Haven't been here for a while but need help with this 92'Z. When accelerating w/very easy throttle, it's fine clear to 4k rpm but any more than easy throttle it starts bucking and missing and falls on its face until it gets good and hot. Then look out, wakes up and gone. Aggravating. Any thoughts?

[A26B]

A Fuel Pressure Gauge is a must have tool for a LT5.
Even if it turns out to not be a fuel problem, it helps greatly when you can eliminate a possibility from the diagnostics process.

what is proper way to check fuel pumps ? .........................................
There are 2 fuel pumps, FP1 is the primary and FP2 is the secondary pump. For a cold start, both FP1 & FP2 will run until the engine reaches appx 176F, then FP2 will shut off. For a hot start, above 176F, both FP1 & FP2 will run, but after 2 sec, FP2 will shut off.

To determine the functionality of the pumps, they must be tested separately. There are 2 fuses. FP1 fuse is on the pass side of the dash in the fuse panel. The fuse is labeled FP1. FP2 fuse is under the passenger side dash kick panel. Remove the panel. The fuse is labeled FP2.

The procedure to check fuel pumps is as follows;

Cold Engine
Key off, Engine off
Attach Fuel pressure gauge line to fuel rail. Bleed down any pressure in the rail.

Testing FP1 (Primary Fuel Pump)

1. Remove FP2 fuse.

2. Turn Key on, Engine off.

3. Observe fuel pressure. Should be appx 45 psig

4. Key off, engine off.

5. Bleed down fuel pressure

Testing FP2 (Secondary Fuel Pump)

1. Replace FP2 fuse and remove FP1 fuse

2. Turn Key on, Engine off.

3. Observe fuel pressure. Should be appx 45 psig

4. Key off, engine off.

5. Bleed down fuel pressure

6. Replace FP1 fuse.
__________________
Jerry Downey
JERRYS LT5 GASKETS & PARTS
http://www.jerrysgaskets.com
1994 ZR-1, Black/Black, Lingenfelter Aerobody, 415cu in, 3.91 gears, coil-over susp, Brembo brakes, etc.
2016 Black-Red, 3LT-Z51 Auto 8-speed.
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[Young1]

Sounds like you have a bad secondary pump. Fuel pressure gauge set is 50 bucks at harbor freight. Ditto Jerry. If fuel pressures are correct then secondaries may not be opening.