02 silverado 4.3 has me stumped.

[455olds]

Greetings all, was looking for a little advice. I have a 2002 silverado with the 4.3. Left out yesterday morning and made it half a block before it started running rough and eventually stalled.

Truck has had no prior issues or signs of a problem.

Verified fuel pressure at rail, 60 psi and slowly dropped to 56 psi after a hour or so.

Strong blue spark, replaced ignition coil and cap/button anyways since it hasn't been done. No security/padlock issues.

P0300 is the only code I have.

Engine will start and run but runs rough and bucks/stalls after 10 seconds or so.

Any advice appreciated. Thanks.

[O_J_Simpson]

How old is the fuel?

[silveradosid]

how old are the plugs and wires

[sporty061200r]

Spider fuel assembly under the manifold

 

 

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[arielleon90]

You should check your plugs I had some what of a similar problem on my 2000 suburban. thought it was a fuel problem so I replaced the fuel pump but it wasn't that. Never checked all the plugs just a few. Then I went and checked all the plugs one had a lot of carbon build up cleaned it out sanded it down a bit and truck has been running smooth since then. Just thought I'd chime in. But mine never stalled just ran rough n got that same code.

 

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[455olds]

Plugs and wires are 1 year old. 10k miles or so. Will pull a few plugs to read them and check the resistance on wires. Any way to check spider other than a visual inspection?

[455olds]

Small update. Plugs and wires checked out fine. Still have good spark at the coil and plugs.

Vehicle will now only start with a secondary source of fuel such as a mist of ether or gas down the tb. Fuel pressure at rail still good 60 psi key on and cranking, no major leakdown. What else effects fuel delivery from the rail down? All I can think of is spider nozzles are stuck or closed or bad ecm driver.

[455olds]

So I'm completely lost. Put a new updated mpfi spider in it, truck started and ran but wasn't quite right. Noticed fuel leaking from the lines where they weren't fully seated, I assumed it was losing pressure and would be fixed upon seating the line fully. No go, back to the original issue. Verified fuel pressure again after spider replacement, still good. Injector pulse is good verified via noid lights.

[Dnt]

I am with the JUICE on this one. If this is a vehicle that does not get driven often you may have built up a high level of ethanol in your tank due to "phase separation" from sitting for long periods of time and never driving enough to get the majority of fuel out of the tank . After reading your responses that would be where I would look first. Or of course you could have gotten a tank full of water last time you filled up. Either way bad gas is my guess.....

 

[455olds]

Truck gets driven every day, just not far distances. I only use fuel from a fleet center and I've never had a problem with it. It's possible. Will check it out.

[455olds]

Another update. Added 1 gallon of gas i had on hand, no initial change. Messed around with it for another 2 hours or so. Out of the blue fired right up and idled well under it's own power for around 30 minutes. No engine codes but now has a misfire. When I lightly rev it to 1500 or so in park it will do well sometimes, other times it has a pronounced miss and engine rpm will drop very low and almost stall out when its returning to idle. Starts well and consistent now. Will change plugs and added 5 gallons of fresh gas tomorrow to see if anything changes.