issue 4.3 gmc sierra

[stefan_gbm]

Alright so usually I can figure out what's wrong with my parents trucks. But here's the problem. Dad truck stopped running fuel pump went out. Replaced the fuel pump it won't start so we replaced the fuel pump relay, still wouldn't start tried a brand new cam sensor and now it's back firing through the intake after a few rotations. It wasn't doing that before hand. The only other thing that crossed my mind was the way the distributor is with how it crosses a cross itself multiple times on the cap. My buddy said it could be the crank position sensor also but I hooked up my programmer to it and got a p0300 code which is a multiple miss fire.

 

[ChrisinVictoria]

Most common is moisture in the distributor cap. Try drying it out or replace the cap. Use an ac delco cap.

 

[stefan_gbm]

We've takin the cap off and cleaned it but I think it's the electrical current that getting interrupted because of the stupid design of the cap

 

[Mooseman]

Possible. Replace the cap and rotor. Check for spark. Could be the coil too.

 

[stefan_gbm]

Just swapped the coil today and still the same problem

 

[gmcman]

Fill us in a little more.....so this truck was running fine then just stopped working, with no prior work done to it? Did you at any time replace or remove any plug wires? If so, did you get them back in the correct location? Most caps have a recess so they can only be installed in one particular location, make sure it's correct.

Don't just clean the cap, if it has miles on it, 60K plus, then replace the cap and rotor as a set. There could be an excessive gap between the rotor and the cap terminals.

When you turn the key to "ON", does the fuel pump run then shut off?

 

[stefan_gbm]

It started running like crap then died when he was driving it. It has pressure you can hear it prime. Tried a quick spray of starting fluid just back fired through the intake. And it's a factory cap and rotor so it's number where the wires go but it does have 107k on it.

 

[gmcman]

I would suspect the coil also....I would plan to replace the cap and rotor first mainly for future preventative maintenance.

This is where I would start, if you don't have a start then I would then look at the crank sensor, ign module.

Does this motor have the HEI coil or a separate coil? I'm assuming HEI but not sure.

 

[gmcman]

Also, I assume there's a timing mark on the harmonic balancer...if so, get the mark on "0" , pull the cap and ensure the rotor is on the #1 terminal, or might be 180 deg off....which is still ok.

 

[stefan_gbm]

Separate coil And changed that to. If the new cap Nd rotor doesn't work the it's the CPS

 

[6716]

I once fixed a bunch of stuff and couldn't start because the tank was empty .....

 

[stefan_gbm]

It's full