1999 Silverado 4.3 problems

[JOSH...BAMF]

My 1999 4.3 Chevy silverado is having some trouble. It started running really crappy randomly just driving down the road. It started sputtering and didnt have any power when accelerating. I replaced the plugs and wires and have just recently had a fuel pump put in. Any tips on what to try next?

[MT-2500]

Originally Posted by JOSH...BAMF

My 1999 4.3 Chevy silverado is having some trouble. It started running really crappy randomly just driving down the road. It started sputtering and didnt have any power when accelerating. I replaced the plugs and wires and have just recently had a fuel pump put in. Any tips on what to try next?

Check that fuel pressure.
Any codes or check engine lights?

What brand of fuel pump was used?
What brand of plugs was used?
Have you got good hot blue spark to all plugs?

How to check fuel pressure.

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

[JOSH...BAMF]

I had my brother in law bring over his code reader and it said cylinder 1 was misfiring. So we took out the spark plugs and checked to see if it had spark and it did not. But the wire was good. The next step was to put the engine at TDC but the crankshaft has four markings on it instead of one to line up and I didnt know which one to line up. What could cause it to have no spark?

[MT-2500]

Originally Posted by JOSH...BAMF

I had my brother in law bring over his code reader and it said cylinder 1 was misfiring. So we took out the spark plugs and checked to see if it had spark and it did not. But the wire was good. The next step was to put the engine at TDC but the crankshaft has four markings on it instead of one to line up and I didnt know which one to line up. What could cause it to have no spark?

Dist setting has nothing to do with the spark.
Does it have good hot blue spark to the spark plug?
What kind of spark plugs are you using?

To find TDC compression stroke remove spark and put finger over hole and crank engine and feel for compression stroke.

The insert a brass or soft wire/small rod and feel for TDC of piston.

The ign. timing is not adjustable on that engine.
Set dist as in picture.
http://files.automotiveforums.com/ga...hp?photo=51302

http://www.automotiveforums.com/vbul...d.php?t=881442

After engine is running you will need to check/set camshaft retard with a good scanner.

[JOSH...BAMF]

What I meant to say was that the wire is not getting any spark we hooked up a tester to it and there was no spark from the wire. My mechanic said that it is not very likely for the distributor to not give power to only one cylinder. He advised to check it at the computer does that sound reasonable? and thanks a bunch for the links to the threads about TDC.

[MT-2500]

Originally Posted by JOSH...BAMF

What I meant to say was that the wire is not getting any spark we hooked up a tester to it and there was no spark from the wire. My mechanic said that it is not very likely for the distributor to not give power to only one cylinder. He advised to check it at the computer does that sound reasonable? and thanks a bunch for the links to the threads about TDC.

How are you going to check that at computer?
I would.
Check for bad plug wire or dist cap and rotor or worn dist shaft.

[Autotropolis12]

I recently purchased a 1999 Silverdo 4.3 V6 that is losing power at 3,500 Rpm's. Truck runs, and accelerates great up until around 3.5k then just pretty much falls flat on its face. There is no spark issues, and I just installed a 40 series flowmaster, and that didn't change the way it ran at all, so I am guessing not an exhaust problem.

I know that this is not a transmission problem due to the fact that if I rev the truck in park, it hits around 4k rpm and then starts to lose power.

When driving, I can floor it at 60 mph...and the truck will not accelerate at all nor will the rpm's increase. BUT if I give it half throttle...it runs fine.....

[MT-2500]

Originally Posted by Autotropolis12

I recently purchased a 1999 Silverdo 4.3 V6 that is losing power at 3,500 Rpm's. Truck runs, and accelerates great up until around 3.5k then just pretty much falls flat on its face. There is no spark issues, and I just installed a 40 series flowmaster, and that didn't change the way it ran at all, so I am guessing not an exhaust problem.

I know that this is not a transmission problem due to the fact that if I rev the truck in park, it hits around 4k rpm and then starts to lose power.

When driving, I can floor it at 60 mph...and the truck will not accelerate at all nor will the rpm's increase. BUT if I give it half throttle...it runs fine.....

If you need help with yours start a New /Thread on it and someone will help you.

[JOSH...BAMF]

The distributor was replaced about a month ago. The mechanic advised us to check for loose wires but we did not find any. I switched wires with another cylinder and it had spark so it is not the wire.

[MT-2500]

Replace the dist cap and rotor with a AC delco cap and rotor.
Let us know how it goes.

[JOSH...BAMF]

Replaced cap and rotor still getting cylinder 1 misfire code. I had a friend tell me this could be because of a worn out timing chain. Does this sound reasonable? The parts are a few hundred and looks like a do-able job for me. Is there any tell tale signs of a worn out timing chain that I can look for before I dig in?

[JOSH...BAMF]

I decided to go with the timing chain after to talking to someone with the exact same problem with no spark down to the same cylinder. I started the job and got the parts but need a smaller bolt on pulley puller so i will buy one tommorow and see how it goes from there. I will post after I finish and let you all know if that is it.

[JOSH...BAMF]

Distributor cap...

[MT-2500]

Originally Posted by JOSH...BAMF

Distributor cap...

Are you trying to tell us it was just a bad cap ?

[JOSH...BAMF]

It was just a bad cap...