My dad's 4.3L V6 Jimmy ran like crap ever since he got it. And we've done several tune ups, changed spark plugs, wires, cap, rotor, whole distributor, intake manifold and plenum gaskets, timing chain, you name it. Nothing helped. Until on a hunch my dad suggested we check the gas pressure and we found that the pressure was 0 except when we cranked the engine, but upon turning off the ignition, it dropped straight to 0 again. Changed the fuel pressure regulator and it made a world of difference! If you step on the gas from a stop, the wheels spin now!

Just thought I'd suggest this, since we've seen numerous crappy-running 4.3L engines and now we have something new to try to make them work right!

A fuel pressure and leakdown test will spot that immediately. Those tests should be the first thing you check whenever any driveability issues occur on a 4.3L engine.

Well we didn't know that, so maybe other people wont.

I used to think the 4.3L just sucked, but now I know it's just misunderstood :P
I still hate it's design, but at least it puts out decent performance when in tune.

First of all, there are several variations to the 4.3l, so casting them all together just because of displacement just does not make sense. For example, and Olds 350 and Chevy 350 are NOT the same. A Ford 351w and a 351c are NOT the same.

Secondly, if you only have fuel pressure while cranking, that has nothing to do with the regulator, that has to so with the pump not being energized at ign on. The system should prime at key on and hold pressure. How much depends on what year and engine you have.

Meh, it's a vortec 4.3L v6, those are all the same between brands. And I should have said that it did get pressure at key on, but it quickly diminished to 0.

I hate this engine anyway. I was just trying to lessen the misery of other people trying to solve the same problem I had.

All that work and money spent and it was the regulator........

First things to check, whether its a 4.3, 5.0, 5.7, 2.2, 1.9,2.4.......

Ignition (spark)
Fuel(pressure and supply)
Mechanical(compression)
Classic example of shot gunning parts at a problem, oh well, at least your dads truck has a ton of new parts and should run good for a while....