My 454 Rebuild

[Supercharged111]

Got the FP changed today and man what a PITA that was! but it's done.
Nothing changed really. 2 FPR's, 2 FP's, 2 fuel pressure gauges and nothing has changed except fuel pressure does not drop when giving it gas and the pressure gauge still reads 45psi. I forgot to look at timing when WOT.
When i swapped the knock sensors from the old engine to the new engine they were torqued to the proper spec but maybe the torque wrench was not reading right?
Im getting tired of changing parts for only slight improvements but, About the only things left are o2 sensors, Knock sensors or camshaft.
I don't mind spending the cash but i hate not getting a fix.
The Distributor bushings are tight and the shaft has no wobble also has a new melanized gear and is reading -0.2(ish) on CMP. could the sensor be acting wonky causing the miss?

Try unplugging the cam sensor and driving it. It'll run in batch fire mode that way. No loss in drivability.

 

[Spareparts]

Thanks. I'll try that tomorrow.
What should i watch/feel for?

 

[Supercharged111]

Thanks. I'll try that tomorrow.
What should i watch/feel for?

If you think it's causing your miss, watch for it to go away. Probably not the cause, but no reason not to try.

 

[Spareparts]

Cool i'll report back tomorrow.
I'm also thinking of loosening the Knock sensors maybe 1/2 a turn and seeing what that does if anything.
I had a scanner put on it at a shop.
They did not test everything but what they did look at and told me was this.
Injector pulses were even.
o2 sensors are working
CPM was set to 0
Map, TPS, IAC appear to be functioning properly.
Ill be back at a shop tomorrow and weather permitting as i'll be outside i can barrow a Snapon fuel pressure gauge and compression gauge.
I'm now at a loss on what might be causing a miss.

 

[Spareparts]

Running the engine in batch fire mode makes 0 difference.
So at my buddies shop i have access to Snapon quality tools.
Here is what i found.
Compression is. I did forget to open the throttle so may actually be a little higher i dunno.
1, 155
2, 155
3, 158
4, 158
5, 155
6, 157
7, 156
8, 155
I don't think i have a mechanical problem with the engine as compression is to even.
According to the scanner im getting random multiple misfires.
Fuel pressure is 47 psi and raises to 50 snapping the throttle open.
He suggested to make sure the ground wire is making good contact as he had a problem with a 94(ish) Suburban with a bad ground wire and also make sure it is getting good power.
If power is not a problem then i have the unfortunate luck of buying 2 miss labeled fuel pressure regulators as both have the same spec of 57PSI but im clearly not getting that.

Anyone know where the ground wire attaches to the frame on a 98 suburban?

 

[Supercharged111]

Probably the same area as my dually.

You must be registered for see images attach

Gotta zoom in to see it on the phone. This was from before I had a bed for it and was scrubbing all the rust off the back of it.

 

[Schurkey]

I don't think i have a mechanical problem with the engine as compression is to even.

Compression can be "even" with failing cam lobes and other faults.

It does signal adequate ring and valve seal, and adequate cam timing.

According to the scanner im getting random multiple misfires.

What are the individual cylinder misfire counts?

Fuel pressure is 47 psi and raises to 50 snapping the throttle open... ...If power is not a problem then i have the unfortunate luck of buying 2 miss labeled fuel pressure regulators as both have the same spec of 57PSI but im clearly not getting that.

Is the fuel pressure gauge accurate?

Electric fuel pumps need adequate power to produce acceptable pressure/volume. I test for voltage, amperage, and voltage on the ground wire. GM tends to use undersized wiring for the fuel pump, so ~3 volts of voltage-drop is fairly normal--2 volts on the supply side, one on the ground side. If the alternator is charging at 14.x volts, the pump is likely running on 12.x volts supply, and with one volt on the ground side; for a total across the pump of 11.x. but less voltage than that is a problem.

Voltage testing MUST be done with the pump running, and as close to the pump as practical--which is usually at the rearmost electrical connector before the harness goes up and over the fuel tank. Amperage testing can be done anywhere in that circuit.

The in-tank harness can also corrode, which wouldn't be shown in a voltage test conducted ahead of that wiring. In earlier years, the harness was replaceable and only about $20. I'm guessing the newer vehicles have the harness, pump, sending unit, filter sock, and all plumbing integrated into a "fuel pump module" that's far more expensive than just replacing the failed parts separately.

 

[Spareparts]

Cylinder misfire counts are all over and not any particular cylinder and can't be nailed down to a specific pattern or cylinder. It goes from 0, 2, 10, 0.. 0, 20, 40,0 it can be any number of cylinders but not more than maybe 4 or 5 cylinders at a time.
Yes the Fuel pressure gauge is correct. 2 of my gauges and his all read the same within 1lb

With the truck running and probing the power wire i get 13.55V about two feet away from the pump connection. Dang forgot already but i believe the gray wire.
The larger black ground wire i have no idea where it connects to the frame at and im not gonna unwrap what could be several feet to find it. I did Ohm check it and the reading is 02.3
At work anything under 20.0 ohm is considered good so i assume my ground is good also.

So potentially this entire fuel problem might be from my own making.
Looking at pictures of pressure regulators i see a small O ring on the center port of the regulator. I don't recall seeing one on the original regulator i replaced last fall for low fuel pressure and i don't recall one on the new one either. Truck ran fine with the same low fuel pressure so i never gave it another thought.
Put new engine in and it has misses i can't figure out. Check fuel pressure and it's low. Install new regulator and still low fuel pressure and i don't remember seeing a little O ring again. Check fuel pressure of new regulator and exactly the same low reading. Ok must be fuel pump. Install a new AcDelco pump and again exact same low fuel pressure.
So now im wondering am i supposed to have a little O ring or not? Would it even have any fuel pressure without that O ring? Is it only able to build 47psi without the O ring?

 

[Piratehunter]

not sure if it helps, just sharing my recent experience with my build. My xr270hr cam generates less vacuum than yours, 15 at idle, jumps to 28 at throttle rap. The fpr I used was ACDelco 217-3073, it idles at 48 and goes to 60 at throttle rap.

 

[Piratehunter]

Cylinder misfire counts are all over and not any particular cylinder and can't be nailed down to a specific pattern or cylinder. It goes from 0, 2, 10, 0.. 0, 20, 40,0 it can be any number of cylinders but not more than maybe 4 or 5 cylinders at a time.
Yes the Fuel pressure gauge is correct. 2 of my gauges and his all read the same within 1lb

With the truck running and probing the power wire i get 13.55V about two feet away from the pump connection. Dang forgot already but i believe the gray wire.
The larger black ground wire i have no idea where it connects to the frame at and im not gonna unwrap what could be several feet to find it. I did Ohm check it and the reading is 02.3
At work anything under 20.0 ohm is considered good so i assume my ground is good also.

So potentially this entire fuel problem might be from my own making.
Looking at pictures of pressure regulators i see a small O ring on the center port of the regulator. I don't recall seeing one on the original regulator i replaced last fall for low fuel pressure and i don't recall one on the new one either. Truck ran fine with the same low fuel pressure so i never gave it another thought.

So now im wondering am i supposed to have a little O ringor not?

yea that little o-ring needs to be on there. Make sure the old one is not still inside there somewhere. That is a common thing to mess up