Need help interpreting fuel pressure test

[mudpie]

Post above edited for pics.

I did the compression test and got the following numbers.

Drivers side, front to back (cyl 1,3,5,7) 150, 135, 140, 120
Passenger side, front to back (cyl 2, 4, 6, 8) all 120

All the plugs smelled like fuel, so I'm assuming the rings are pretty fuel soaked too. I can't find my oil can to squirt some oil in and do the test again, but for now I'm not too worried about those numbers. If any of them were something weird like 90 then I'd worry.

I went through the troubleshooting process posted previously, and it seems to point to the FPR, but I don't have the tools to plug the line and actually do the final test though, so it's just a semi-educated guess. I noticed that the side of the engine that had the lowest numbers is the same side the FPR is on. Would there be a connections, or just a coincidence? Should I expect to find my pressure regulator actually leaking into the upper intake?

Also, I don't know how or when the injectors fire. At first I was thinking those plugs were oil fouled. Maybe it's just running really rich? What would cause that with this fuel injection system, especially if my fuel pressure readings are low? Seems odd that every single injector would be bad at the same time. Do they spray whenever it's cranking, in which case fuel on the plugs would be normal?

 

[tom joyce]

The valve seals are shot - the plugs are seriously oil fouled and worn out - change the plugs, and I would change the valve seals.
Compression numbers are good, so rings are good.
It is very unlikely that it is the fuel pressure regulator, because it has the updated version spider assembly.
Check and CLEAN the fuel pump ground (connects to the frame just before fuel tank). It is known to corrode and cause all kinds of issues.
Fuel injectors fire when the computer applies a ground to the injector. There is 12v all the time to the injectors..-- CHECK ALL ENGINE GROUNDS....
There could be all kinds of crap inside of the fuel tank, being that three fuel pumps were changed. I would drop the tank and clean it out...

For me, the look of those plugs would be cause for removing the heads and rebuilding them...But that is just me...

 

[mudpie]

Valve seals I can cope with for the time being, as long as I can get it running again. I'll get some junk yard heads and rebuild those to make the process easier. My local Pick n Pull has a half price sale coming up.

I got the upper intake pulled off. Looks kinda yucky, for lack of a better word, but it's got 450k on it so I suppose it's not too bad. I originally tested the fuel pressure with a loan-a-tool gauge that I got from Autozone. I've since returned it, so I can't do another test today since they're closed. Christmas....what can you do?

I tried to run the pump with a jumper wire in place of the relay, but it didn't come on. Did I disconnect something when I pulled the upper intake that would make the pump not run? A ground maybe? It didn't run with the key on either, and it definitely ran yesterday.

I'm attaching a link to the folder where I have several pics...the plug pics that I posted above, and 3 intake pics, and the jumper wire. I'm assuming that wire is connected correctly?

https://photos.app.goo.gl/Il1OJr0QXPgvTKHw2

I appreciate the help.

 

[east302]

Not sure about the jumper at the relay, but there's a single red wire connector at the driver firewall at the fusible link box. Connect a fused jumper from that connector to a spare post at the fusible link box and it'll run the pump.

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[tom joyce]

Valve seals I can cope with for the time being, as long as I can get it running again. I'll get some junk yard heads and rebuild those to make the process easier. My local Pick n Pull has a half price sale coming up.

I got the upper intake pulled off. Looks kinda yucky, for lack of a better word, but it's got 450k on it so I suppose it's not too bad. I originally tested the fuel pressure with a loan-a-tool gauge that I got from Autozone. I've since returned it, so I can't do another test today since they're closed. Christmas....what can you do?

I tried to run the pump with a jumper wire in place of the relay, but it didn't come on. Did I disconnect something when I pulled the upper intake that would make the pump not run? A ground maybe? It didn't run with the key on either, and it definitely ran yesterday.

I'm attaching a link to the folder where I have several pics...the plug pics that I posted above, and 3 intake pics, and the jumper wire. I'm assuming that wire is connected correctly?

https://photos.app.goo.gl/Il1OJr0QXPgvTKHw2

I appreciate the help.

Not sure if the jumper in the relay is the correct pins - I will check later on mine...BUT that will run the pump -- as will east302's suggestion....
Nothing on the upper intake that you removed will cause the pump not to run... Test for voltage, don't just assume there isn't 12 volts getting to the pump...cus it can be a ground issue...
The most important ground for the fuel pump in under the truck. Crawl under the truck and follow the harness wires that connect to the pump. There will be a black wire breaking out of the harness that connects to the frame...That is the fuel pump ground...Make sure the ground is good...I actually run a #12 wire from the battery ground to the fuel pump ground - just to insure here is a good ground there...
Great idea with the heads.
With 450k, and leaking valve seals, the intake looks pretty good.

 

[Ken K]

east302 is correct... If your fuel is leaking back into the tank, it is leaking past the check valve built into the fuel pumps outlet. It can only go into the tank, thru the regulator, leak past an injector or drip onto the ground. Now, ask yourself where & why? Leak testing is important part of diagnostics. Then, ask yourself, how many tanks of gas have been ran thru this vehicle. If math was easy, say one tank of gas per month, over 21 years is about 252 tanks of gas. How many times has the plastic tank been removed and cleaned with hot water? ...shaken, not stirred. The GM diagnostic flow charts includes an area for symptoms and many lead back to fuel because it is a component, just like a fuel pump, filter or injector. E85 in a non flex fuel vehicle has happened.
I guess, because I rebuilt carburetors for decades, few inlet paper filters I cut apart, let dry, were clean. (I checked all) Most had a spoon full of fine dust when dumped onto a white shop towel. This dust, dirt and whatever comes from each gas station and finds its way into your tank. Why would the same OEM fuel pump, that lasted for 20 years fail so soon? Other than damage to electrical terminals due to over heating and well known issues up front... I am sorry, the tank has to come out.
I know of shops, who learned this and clean every tank as a part of pump replacement, and never had a come-back. As service technicians worst nightmare, as it does not pay very well the second time. The "Bucket Type" fuel pumps found in newer trucks and older cars, collect all of the junk in the tank, like a vacuum. They deserve a look inside. Most "MRA" type pumps, can have the bucket removed with a pocket flat blade screwdriver. You'll be surprised to see how black the inside pump filter and what remains in the buckets bottom. Just saying.
The best technicians are born from mistakes, short-cuts, experience and best practices. That is why this forum allows everyone to benefit from a thousand plus years of knowledge from the like minded masses.
Good luck and God bless.

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[mudpie]

For the benefit of anybody doing a search in the future, I've got a bit of ignorance to report on my part...

I had left the key in the ignition overnight, turned to "on". Next day my battery was dead. The only charger I have is a 2 amp trickle charger for my motorcycle, so I put that on and let it sit all day. About 7 pm I check it, charger indicates that the battery is charged, but it's dark and cold so I unplug it and plan to work on it the next day.

Next day I go out and the battery is totally dead, so I go buy a bigger battery charger. Hooked it up, let it sit for 5 hours, and the light on the charger says the battery is done. I put the key in the ignition to try and do a fuel pressure test, and I've got no interior light, no lights on the dash, nothing. Checked every fuse, every ground I could find, and still nothing. Measured voltage in the battery and it's maybe 2v, if that.

The truck has an Optima red top battery. What I didn't realize is that those require either a special charger, or a special procedure to charge them at home. The info is on the Optima website, if you're one of the people like me who weren't already aware of this.

I took it to Autozone, and they tell me they have a special charger just for these batteries, but it will take all day. Hopefully this evening some time, I'll be back on track.

Thanks for all the input. It's been very helpful.

 

[df2x4]

The truck has an Optima red top battery. What I didn't realize is that those require either a special charger, or a special procedure to charge them at home.

Coming from someone who's run nothing but nice AGM batteries for the past decade or better, both of these things are 100% false. You can charge them on anything that will charge a standard lead acid battery and not hurt a thing.

Hate to say it, but more likely what you're dealing with is the fact that Optimas are now produced by Johnson Controls in Mexico and their quality has dropped significantly. I feel like I've posted this a million times, but I killed two Optima yellow tops in my red truck in about six months. Switched all my vehicles to Odyssey Extremes after that, no more issues.

 

[mudpie]

I'm not sure how you charged yours. If it worked for you, cool. My experience has been different. This is from the Optima website:

"Most battery chargers have built-in safety features that may prevent chargers from recharging deeply discharged batteries. A traditional battery that's at 10.5 volts or less is seen as defective, having either a short, a bad cell or some other defect. Most analog chargers are binary and are either on or off. If they don’t come on, it may be because the charger thinks the battery is “bad.” Turning on to charge a “bad” battery could create an unsafe scenario. But the fact is that the AGM battery may be just fine; it has simply slipped below the minimum voltage threshold of the charger to turn on, and the charger doesn't know what to do with the battery, so it does nothing."

I did a google search for "optima battery won't charge" and came up with dozens of websites and car forums that all say the same thing. Almost all of them mention using a newer charger with a specific "AGM" setting, or charging it in parallel with a good battery so the charger sees a voltage above 10.5.

I'm not trying to be argumentative. Maybe you're right...maybe new production methods have altered the way the newer ones charge. I don't know. What I do know is that I've been stuck for 2 days with a dead battery that neither of my chargers would charge.

I do appreciate differing opinions though. It feeds my curiosity. Thanks

 

[df2x4]

I'm not sure how you charged yours. If it worked for you, cool. My experience has been different. This is from the Optima website:

"Most battery chargers have built-in safety features that may prevent chargers from recharging deeply discharged batteries. A traditional battery that's at 10.5 volts or less is seen as defective, having either a short, a bad cell or some other defect. Most analog chargers are binary and are either on or off. If they don’t come on, it may be because the charger thinks the battery is “bad.” Turning on to charge a “bad” battery could create an unsafe scenario. But the fact is that the AGM battery may be just fine; it has simply slipped below the minimum voltage threshold of the charger to turn on, and the charger doesn't know what to do with the battery, so it does nothing."

I did a google search for "optima battery won't charge" and came up with dozens of websites and car forums that all say the same thing. Almost all of them mention using a newer charger with a specific "AGM" setting, or charging it in parallel with a good battery so the charger sees a voltage above 10.5.

I'm not trying to be argumentative. Maybe you're right...maybe new production methods have altered the way the newer ones charge. I don't know. What I do know is that I've been stuck for 2 days with a dead battery that neither of my chargers would charge.

I do appreciate differing opinions though. It feeds my curiosity. Thanks

How do you know your experience has been different if you haven't retrieved the battery from the parts store yet? Like you, not trying to be argumentative, but I can almost guarantee you that the chargers are not the issue here.

The procedures you found for charging AGM batteries really apply to any 12V battery. AGMs especially do not like sitting with a low charge level, though. The "special" chargers for recovering deeply discharged AGM batteries are simply high amperage "dumb" chargers that have no safety features. Pump some current through them to get them back to a reasonable level and any 12V charger will top them off. There are no safety features built into Optima batteries. The safety features are in most of the consumer level battery chargers built in the last decade or so, they simply won't turn on if the measured voltage of the battery is too low.

From experience and many years of working with these things, you don't need any fancy charging procedures or special equipment.

EDIT - To clarify, the reason I'm so gung-ho about trying to tell you it's not the chargers is related to personal experiences with my failed Optimas. I had one yellow top that woud behave exactly as you describe. Multiple chargers appeared to be working fine, came up to the appropriate voltage and shut off like normal. Once I disconnected the charger, voltage would immediately drop to below 9V and the truck would fail to crank. Had that battery load tested and it was capable of almost zero cranking amps. There was an internal short somewhere inside the case that caused the issue.