cfrazier34

I have a 1993 Chevy Silverado 6 cyl. 4.3 engine, 2 wd, extended cab. I have a problem with the engine missing or acting like a back fire when I give the gas for pickup or going up a hill. If I down shift it is a little better, but when I cruise there is no problem. The mechanic checked fuel pump. changed fuel filter, and checked plugs. He searched for the problem and thought it might be a flat cam. I don't understand this, but I think he might be guessing. the engine now has 175m miles on it. If I am idling it will run smooth and then miss a beat. Any ideas?

funbunch

Same here. Wife noticed 2003 Sub K1500 hesitating and reported to me 3 days ago. She had just purchased a full tank of mid grade. I first checked the fuel filler cap. It is snug. I got a can of Sea Foam, in case trash or water entered the system. I've replaced spark plugs OEM, then plug wires. I have the fuel filter to install this afternoon.
I observed hesitation first under stress at 3500 RPM, but then even at 1800.
Initially observed after reaching operating temp - now, 4 days later it's at cranking and slow driving
Dealers tech listened and replied its the fuel pump "going"
Doesn't the fuel pump just fail like a light switch?

Bjmac

It's not a flat cam. Since it only happens under load and backfires, I would check the distributor cap. Is this a z engine?

Bjmac

A fuel pump can slowly degrade over time. Did anyone check the fuel pressure on it? What engine do you have?

Mishimoto

When your engine is under load (going up the hill) it will have a more pronounced misfire then when at cruise. What about plug wires and like Bjmac said, your cap?

funbunch

Thank you Bjmac!
VIN "Z" 5.3 L V8f
O'REilly quoted $275 for replacement fuel pump.
Your comment is consistent with new info I received privately.
Hey, already replaced OEM plugs, wires, filter - it'll have close to a full tune up!

funbunch

The tranny 4L60E lurches forward in Park, Rev, Neutral,D, 3,2,1 now (four days)
Was able to rock the vehicle 8 feet backward after chucking shifter in neutral. It stubbornly failed to move forward/backward.

Keep ya'll posted

kevinkpk

Cannot remember if this is OBD1 or 2? Is there a check engine light?

cfrazier34

No check engine light comes on at all .

kevinkpk

What I would recommend, parking brake set, and wheels chocked, with insulated pliers, pull plig wires one by one. If the engine misses, go to the next till you pull a wire, and the engine dosen't change. That will isolate at least to that cylinder. Pull the spark plug, it could be a plug wire.