Code 25 Fuel lean (1 Viewer)

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Oct 16, 2004
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Kinda long
A couple of months ago I pulled the starter disconnecting the negative battery. Store had wrong starter so I put the old one(hesitant but would turn over) back on. Hooked up battery and the problems began. Though the engine light was already on she was running fine until now. At this point she had a miss. Figuring the ECU was relearning I didn't worry. Four weeks and four cans of Seafoam later she will not start. A slight sputter but will not run. Over the four weeks I replaced the fuel filter and the plug wires. This didn't help. Problem steadily got worse till one morning she wouldn't start (turned over but wouldn't crank). Replaced plugs, cap and rotor to no avail. Compression test showed 150 or better across all cylinders. Bench tested the O2 sensors and thought they failed. Without the truck running I couldn't test them per FSM. Replaced them. Tested fuel pump per FSM and it passed. Fuel pressure shows 48psi. She has 338151 miles on her and I'd like to get more. Ideas?

Thanks
Chris
 
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Pulled the fuel pump to see what the fuel looked like. It was clear and clean as was the pump filter. I did however notice where a wire apparently grounded itself in the tank. No idea if it's related or not but it can't be good!
P4100049.jpg
 
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Delayed Pressure on Fuel Pressure Test

How long did it take for the fuel to build up to 48 psi when you did your fuel pressure test? I am still looking for a solution to help you my friend. Pls keep me informed. :popcorn:
 
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It took just under a minute to slowly build up to 48psi. I have no clue if that's normal or slow
 
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Stumped the forum? Sweet! I mean CRAP! While it's nice to know I'm not the only one it confuses, it sucks having a down DD :bang:
 
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Well, lets take a shot at this.
Is there a way to test the MAF?
Is there a possible vacume leak somewhere causing the lean code, which could happen.
And a shot in the dark here, what is the condition of your rubber air intake hose?
Even the smallest crack will cause the truck to run like crap and sometimes not run at all.
Just some thoughs here.
 
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Did you pull the trouble codes from the ECU?
You may want to check all the fuses, especially the positive post in line fuses. Almost sounds like an electrical issue to me.
 
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Thanks Roger,
Went through a bad MAF and air intake hose back in '06. Replaced both then. Some similarities between then and now. Pulled the hose and no obvious cracks. Still flexible like new so I don't suspect dry rot. Also back in '06 I replaced all the smaller vacuum hoses (at least the ones I could see).I've checked again and again to see if any are disconnected. Will do a search on testing the MAF.
Thanks McGuilacuddy,
Check the code by the "paper clip" method. It's a code 25 (lean air condition). I also was thinking electrical at first being that it all started after disconnecting then re connecting the battery ground. Been downhill since! The EFI fuse is good but I'll check the relays. I do have fire at the the spark plugs. Also truck is in time. I checked that when it still ran.

I appreciate the ideas! Gives me a direction. I will run some tests and get back. (hopefully tomorrow)
 
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Can you get the plugs to spark now?
What about your injectors?
If the timing is correct, you are getting spark and good fuel pressure, I would have to suspect the injectors are not working for some reason. You could probably pull one of the plugs off (probably #1 the easiest to get to) and check to see if you are getting current when you are turning the motor over.
Could be a bad ECU.
I always pull both the positive and negative wires off when I am working on electrical issues. I'm not totally sure but you could have created a grounding source by some type of conductor touching the body or the motor.
 
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It's working again!

Had the fuel rail open on one end after pulling the fuel pressure gauge off three days ago. Decided to pull the fuel pressure regulator (to open the other end of the fuel rail) before hooking the back side back up. Used air to blow out the gas so I could pour in Seafoam to soak the injectors. Put the regulator back on last night and after two frustrating hours got the fuel line hooked back up at the back side of the rail. With everything hooked back up I was ready to try a few new ideas. Decided for the Hell of it I'd give her a try. After running the starter a little longer than one should she sputtered trying to crank. Several tries later she cranked, spitting and sputtering a few seconds but then smoothing out. Have driven roughly 15 miles and she is smooth with no codes. I'm a happy cruiserhead!
Thanks again guys for the responses!
 

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