Need help with a 2002 5.3

[max 02]

When you mentioned engine bay fire chills ran down my spine. My custom 71 Elky somehow filled the pan with fuel and blew causing fire. I went thru 6 extinguishers with most either not working or only for a few seconds. Totaled the car waiting on FD. Wasnt aware the power can settle and pack on bottom.

Good time for readers to pull their fire extinguishers, turn upside down and gently tap bottom with rubber mallet to loosen the powder, then give them a few shakes until you can feel the powder is loose again. I now do this about every 6 months.

Good advice!
I was real happy I had one close enough!

 

[max 02]

Might want to change the fuel filter in case it’s plugged and not getting the right pressure to the injectors. 5 year old gas??

Yup 5 year minimum.


I’m thinking a bit to old school. I should be more teck and do it right.

Hope I don’t Fock it all up being cheep. I really like the truck, very similar to my old 02 duramax, in colour and interior only, but we dove that truck since new for over 20 years.

 

[88Silverado]

Yup 5 year minimum.


I’m thinking a bit to old school. I should be more teck and do it right.

Hope I don’t Fock it all up being cheep. I really like the truck, very similar to my old 02 duramax, in colour and interior only, but we dove that truck since new for over 20 years.

Dont know how much gas is in the tank or if its going bad but it might not hurt to dump a bottle of Seafoam in there.

Good luck

 

[max 02]

Dont know how much gas is in the tank or if its going bad but it might not hurt to dump a bottle of Seafoam in there.

Good luck

Tank was empty. Or at least didn’t register on the fuel gauge. I filled it with 5 gallons of fresh gas and actually grabbed a bottle of seafoam for it today.

 

[max 02]

Check the fuel pressure regulator. My money is on the diaphragm in the fuel pressure regulator ruptured and fuel is getting pushed through the vacuum line to the intake.

Pretty easy to find. If you take the vacuum line off at the regulator and fuel comes out you found it. If you do, the intake is likely full of fuel too. So even if you pumped the cylinders with the plugs out, there is more in the intake to be pulled right back into the cylinders.

If you find fuel in the intake you just need to bite the bullet and remove the intake to clean it out.

As Wes eluded to I’ve been through this exact problem and I’ve got a nice hole in the oil pan of my 8.1 to show for it. The fuel system is the same on the early 5.3’s.

Checked the vacuum hose on the regulator this afternoon it’s nice and dry.

 

[max 02]

Put some old BFGs on a set of 17s I stole off my plow truck. Can of Seafoam in the tank.
Went for a drive up the road.
No power didn’t want to shift properly, wanted to stall.

Fuel filter ordered. See what that does.

 

[tRustyK5]

Nice job so far!! Just don't let Bart eat the seats...

 

[max 02]

Nice job so far!! Just don't let Bart eat the seats...

lol No that would be bad.

 

[max 02]

Playing with it a little bit.
Still runs terrible, no power.

Changed the fuel filter, no change.

Hooked it up to a Matco scanner… I don’t know how to use it very well, but I did find 3 cylinders misfiring.
Number 1,7,8 I pulled the wires off the coils while it was running,one at a time,they all had spark at least. Number 1 now seems to have no miss. But still on 7and 8.
The rail pressure is different from one side to the next. No clue what it should read?
The timing went anywhere from 12 to 30 at idle.

Also pulled the vacuum line off the fuel pressure regulator while it was running, made absolutely no difference in how it ran.

I want to test the crank position sensor next, and the fuel pressure regulator.

Reader didn’t say there was any problem with the injectors.

Any advice? Or am I going about this all wrong?

 

[ZooMad75]

Playing with it a little bit.
Still runs terrible, no power.

Changed the fuel filter, no change.

Hooked it up to a Matco scanner… I don’t know how to use it very well, but I did find 3 cylinders misfiring.
Number 1,7,8 I pulled the wires off the coils while it was running,one at a time,they all had spark at least. Number 1 now seems to have no miss. But still on 7and 8.
The rail pressure is different from one side to the next. No clue what it should read?
The timing went anywhere from 12 to 30 at idle.

Also pulled the vacuum line off the fuel pressure regulator while it was running, made absolutely no difference in how it ran.

I want to test the crank position sensor next, and the fuel pressure regulator.

Reader didn’t say there was any problem with the injectors.

Any advice? Or am I going about this all wrong?

View attachment 471353

View attachment 471354

The cylinder misfires are your problem. Look at it this way, if fuel pressure was an issue, it would effect all injectors the same way, not one or two alone. That being said, you should only have one port to check the fuel pressure. It should be between 55-62psi. Timing is computer controlled and will move around depending on other factors.

Pulling the vacuum source from the pressure regulator should bumped fuel pressure slightly, as it would simulate going to WOT with no vacuum on the regulator. Again, fuel pressure would effect all the cylinders.

No need to check the crank sensor. If it's running and you have a tach signal, it's working. Normally if you loose the crank sensor it won't even run. It can run without the cam sensor, but typically it would have an extended crank so the ECM can figure out where #1 was after a couple of revolutions. Cam signal or Crank signal would not effect one or two cylinders.

You need to focus on the misfires. The two cylinders that are still acting up may have spark but have you pulled the plugs? If the plug looks decent, I'd start moving items one at a time and see if the problem follows the part. Move the coil from a misfiring cylinder to a known good one. If the problem moves, it's the coil. If it doesn't it's not. Change the wire from the misfiring cylinder to a known good one. It's a big game of process of elimination. If the problem stays on the cylinders you moved from it's time to take a close look at the wiring to the coils and injectors to those cylinders. 7 & 8 are on opposite banks with separate coil wiring and separate injector wiring, so it's probably not anything common between the two. I'd be looking for a chaffed or chewed circuit at that point.

 

[max 02]

The cylinder misfires are your problem. Look at it this way, if fuel pressure was an issue, it would effect all injectors the same way, not one or two alone. That being said, you should only have one port to check the fuel pressure. It should be between 55-62psi. Timing is computer controlled and will move around depending on other factors.

Pulling the vacuum source from the pressure regulator should bumped fuel pressure slightly, as it would simulate going to WOT with no vacuum on the regulator. Again, fuel pressure would effect all the cylinders.

No need to check the crank sensor. If it's running and you have a tach signal, it's working. Normally if you loose the crank sensor it won't even run. It can run without the cam sensor, but typically it would have an extended crank so the ECM can figure out where #1 was after a couple of revolutions. Cam signal or Crank signal would not effect one or two cylinders.

You need to focus on the misfires. The two cylinders that are still acting up may have spark but have you pulled the plugs? If the plug looks decent, I'd start moving items one at a time and see if the problem follows the part. Move the coil from a misfiring cylinder to a known good one. If the problem moves, it's the coil. If it doesn't it's not. Change the wire from the misfiring cylinder to a known good one. It's a big game of process of elimination. If the problem stays on the cylinders you moved from it's time to take a close look at the wiring to the coils and injectors to those cylinders. 7 & 8 are on opposite banks with separate coil wiring and separate injector wiring, so it's probably not anything common between the two. I'd be looking for a chaffed or chewed circuit at that point.

Thank you very much! That will save me some headache and give me a direction.

I was also wondering if there as a bad ground. And the truck definitely had mice so certainly the wires could be chewed.