'94 5.7L rough idling problems, possible fuel pump. Need ideas/suggestions.

[jcoatswo]

From everything I've read I 100% agree with 94Sierra4x4. I see no other reason for the knock other than 2 or more plug wires being crossed. If you're absolutely sure your timing is correct the only thing I would see causing your issue would be an actual rod knock. There could be other very unlikely causes like running ridiculously lean because of a clogged fuel filter or bad pump but there would be other signs of that like a long start or stalling. If the truck was in my driveway I would double and triple check the plug wire locations. Also did your mechanic put a new or used distributor on? My truck is a 1995. When I replaces one of my motors with a junk yard one I tried to use the dizzy that came with the junk yard motor which was an 89 and it wouldn't fire, replaced it with my original and haven't had any problems.

 

[LSUfan71]

Unless I had the #1 cylinder at TDC on the exhaust stroke...

 

[LSUfan71]

From everything I've read I 100% agree with 94Sierra4x4. I see no other reason for the knock other than 2 or more plug wires being crossed. If you're absolutely sure your timing is correct the only thing I would see causing your issue would be an actual rod knock. There could be other very unlikely causes like running ridiculously lean because of a clogged fuel filter or bad pump but there would be other signs of that like a long start or stalling. If the truck was in my driveway I would double and triple check the plug wire locations. Also did your mechanic put a new or used distributor on? My truck is a 1995. When I replaces one of my motors with a junk yard one I tried to use the dizzy that came with the junk yard motor which was an 89 and it wouldn't fire, replaced it with my original and haven't had any problems.

It was a new distributor, the wires are correct now.

 

[jcoatswo]

If needed you can take the driver side valve cover off and watch the valves to see when they move to determine which stroke you're on. I've found thats the best way to go about it if you dont have compression tester or a 2nd person to hold their finger on the spark plug hole.

 

[LSUfan71]

If needed you can take the driver side valve cover off and watch the valves to see when they move to determine which stroke you're on. I've found thats the best way to go about it if you dont have compression tester or a 2nd person to hold their finger on the spark plug hole.

Thanks, I've been googling to try and find a way to determine compression stroke without removing the valve cover.

Last night the truck was idling fine but under the timing light the notch on my damper was not visible, wasn't anywhere near 0º. I have no idea how that's possible.

 

[LSUfan71]

If needed you can take the driver side valve cover off and watch the valves to see when they move to determine which stroke you're on. I've found thats the best way to go about it if you dont have compression tester or a 2nd person to hold their finger on the spark plug hole.

I pulled the valve cover, put the damper notch at TDC with the #1 valves closed. The rotor is pointing at #1 (abt 5 o'clock position). And it's not starting. I'm getting spark.

It was starting last night. Ideas?

 

[LSUfan71]

Just took this vid, what can you guys tell me about it?

http://youtu.be/Cw3PSMQI9oA

 

[beaugott]

I would check coil. Sounds like it could be going and usually if the dizzy goes so does the coil.

 

[LSUfan71]

I would check coil. Sounds like it could be going and usually if the dizzy goes so does the coil.

I am getting spark at the plugs, can the coil still be bad and provide spark at the plugs?

 

[94Sierra4x4]

I am getting spark at the plugs, can the coil still be bad and provide spark at the plugs?

What colour is the spark? It could be weak