HELP ME!!!

[HiHoeSilver]

Without the manual for your truck, who knows what it should be? I do know this, a scan tool will show actual fuel pressure and commanded fuel pressure and has short and long term trims that show you if the pump is keeping up with what the computer wants.

Now my engine is a different generation but the fuel pressure is always 43.5 psi running and might drop to 42 at full throttle for a second or so. I just checked it this morning and LTFTs were 1.38; whatever that means. Haven't read the manual yet.

When you shut the engine off, how much fuel pressure bled off within two minutes?

LTFT at 1.38 is good. Want to see between - 5 & 5. Obviously, 0 is the goal. LTFT are basically moving 0 for the STFT. As they stray, the truck should use STFT to bring them back. This is a good indicator of where lean or rich codes are coming from. If you have a vacuum leak and you get on the gas (as you get farther from vacuum towards stoich) you will see the STFT pull hard against the LTFT. if you have a fuel delivery problem you will see them continue to get worse.


What do your trims look like under load @theprovider? I thought you had a rich code? Am I confusing threads?

 

[theprovider]

Knock sensor code. I need to get a longer hose for the fuel pressure gage so I can see it while Driving. The one I have is just a tad to short to get it under the wiper.

Also this seems awfully loose and the bolt is as tight as it gets.

 

[theprovider]

LTFT at 1.38 is good. Want to see between - 5 & 5. Obviously, 0 is the goal. LTFT are basically moving 0 for the STFT. As they stray, the truck should use STFT to bring them back. This is a good indicator of where lean or rich codes are coming from. If you have a vacuum leak and you get on the gas (as you get farther from vacuum towards stoich) you will see the STFT pull hard against the LTFT. if you have a fuel delivery problem you will see them continue to get worse.


What do your trims look like under load @theprovider? I thought you had a rich code? Am I confusing threads?

Freeze frame two by Chris Nelson, on Flickr


Here's the fuel trim readings right after the cel went off.

I really really appreciate everyones input. A little back story on the fuel pump being replaced. So I took the truck in for the issue I'm having, the guy said most likely fuel pump, very common failure point with these trucks. He had the truck for 1.5 weeks....I was pretty annoyed cause he told me it would be done in a day. Long story short he returned it to me, said he replaced the pump but didn't fix my issue so, he didn't charge me! I thought it was weird but whatever, he's my neighbors friend so I thought he was doing me a solid. I crawled under the truck today and it doesn't even look like the straps were removed. So now I'm thinking the pump wasn't actually replaced. A friend of mine told me the pump might be sucking up crap from the tank since previous owner never filled it and always drove it on E.

 

[Tonyrodz]

Knock sensor code. I need to get a longer hose for the fuel pressure gage so I can see it while Driving. The one I have is just a tad to short to get it under the wiper.

Also this seems awfully loose and the bolt is as tight as it gets.

Pretty sure that should be mounted solidly. Check base of it, if it isn't broken maybe at some washers under the bolt. That should tighten it up.

Freeze frame two by Chris Nelson, on Flickr


Here's the fuel trim readings right after the cel went off.

I really really appreciate everyones input. A little back story on the fuel pump being replaced. So I took the truck in for the issue I'm having, the guy said most likely fuel pump, very common failure point with these trucks. He had the truck for 1.5 weeks....I was pretty annoyed cause he told me it would be done in a day. Long story short he returned it to me, said he replaced the pump but didn't fix my issue so, he didn't charge me! I thought it was weird but whatever, he's my neighbors friend so I thought he was doing me a solid. I crawled under the truck today and it doesn't even look like the straps were removed. So now I'm thinking the pump wasn't actually replaced. A friend of mine told me the pump might be sucking up crap from the tank since previous owner never filled it and always drove it on E.

Just gets better and better--doesn't it?

 

[theprovider]

So I got a longer hose to test while driving. Around the 34 Mark is when it starts doing it. You can see the needle on the gauge kind of bounce around. I was actually accelerating up a bridge when it started.

I did notice that after the tank was filled (89) it stumbled and hesitated a lot more at highway speeds and acceleration. I’m now at a little over half a tank.

 

[swathdiver]

I'm thinking FPR and or Fuel Pump but waiting for the GMT800 guys to chime in.

 

[theprovider]

I’m leaning towards pump or dirty screen on the pump. It drives a lot worse with a full tank of gas I noticed. Also I pulled the vac line off the FPR and the gauge spiked. I read that was a good sign and the FPR is doing it’s job. It looks Pretty new and so does the vac line

 

[bottomline2000]

Sounds about right. No reason for the pressure to drop like that. It's also been known that new pumps out the box have been bad. I had a FPR i replaced 3x because each replacement had a different issue. First one leaked, One read low, the other buzzed constantly and I finally switched to a BWD branded one and it was fine.

Is your FPR on the rail? If so check the vacuum hose and make sure it's not cracked or torn.

I saw the video revving the truck, try the same thing powerbraking it to put some load on the system and see of it drops. I would drive it around first to get everything warmed up..running a truck low on wont make it pick up more dirt than normal since the pick up is from the bottom of the tank. It could make the pump run warmer than normal since fuel is used to keep the pump cooler which is why I said drive it around first.


And just for the record...fuel pumps love to fail when u have a full tank of gas..happened to me during an ice storm..fun times..

Edit- u already addressed the FPR as I was posting lol. Pulling the hose let's fuel flow unregulated so what u saw was normal.

Sent from my SAMSUNG-SM-T377A using Tapatalk

 

[Tonyrodz]

Sounds about right. No reason for the pressure to drop like that. It's also been known that new pumps out the box have been bad. I had a FPR i replaced 3x because each replacement had a different issue. First one leaked, One read low, the other buzzed constantly and I finally switched to a BWD branded one and it was fine.

Is your FPR on the rail? If so check the vacuum hose and make sure it's not cracked or torn.

I saw the video revving the truck, try the same thing powerbraking it to put some load on the system and see of it drops. I would drive it around first to get everything warmed up..running a truck low on wont make it pick up more dirt than normal since the pick up is from the bottom of the tank. It could make the pump run warmer than normal since fuel is used to keep the pump cooler which is why I said drive it around first.


And just for the record...fuel pumps love to fail when u have a full tank of gas..happened to me during an ice storm..fun times..

Edit- u already addressed the FPR as I was posting lol. Pulling the hose let's fuel flow unregulated so what u saw was normal.

Sent from my SAMSUNG-SM-T377A using Tapatalk

Happened to me too. I just filled the tank on a brand new pump. Died.

 

[theprovider]

Well I'm dropping the tank tomorrow. I've got a pump so fingers crossed my issue gets fixed and I don't have to throw several pumps at it.

brb with results

Also these heater hose connections can suck my butt

Untitled by Chris Nelson, on Flickr

Replaced them while the babies were asleep....black one was leaking like a mofo.

Untitled by Chris Nelson, on Flickr