P0505 + throttle body cleaner = dead engine

jeff6times7

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Texas
My "new" 2002 Wrangler Sport has about 50k miles and was a champ for about 3 weeks. Yesterday, at idle, the motor died. I got it started and I could keep it running if I didn't let it idle. Within a minute, I could let it idle. When I got it home, I checked the code with my OBD tool and it said P0505 (and only P0505) so I cleaned the throttle body using Jerry's instructions here:

https://wranglertjforum.com/threads/p0505-code.56654/post-996151

Before cleaning, the idle RPMs were about 500 and after cleaning about 750. The motor sounded good so I took it for a drive. About a 1/2 mile later the motor died suddenly and I couldn't get it running. It cranks but acts like it's not getting fuel or not getting spark.

No other codes are showing. I've been reading but not from the service manual I ordered because it hasn't arrived yet. I think it would be a good idea to hear some wisdom before proceeding.
 
Try this.... cycle the ignition switch on-off-on (not to Start) 12-15 times, keeping it in the On position for 2 seconds each time. If it starts after that you either have a bad fuel pressure regulator or a bad fuel pump.

Non-starts soon after it has been running is normally a bad FPR. Non-starts only after it hasn't been running for a while are normally caused by a bad fuel pump.
 
Before
Try this.... cycle the ignition switch on-off-on (not to Start) 12-15 times, keeping it in the On position for 2 seconds each time. If it starts after that you either have a bad fuel pressure regulator or a bad fuel pump.

Non-starts soon after it has been running is normally a bad FPR. Non-starts only after it hasn't been running for a while are normally caused by a bad fuel pump.
Before I saw your reply, I tested the fuel pressure at the rail. Without the ignition ON, zero psi. With the key in the ON position, zero psi. I cranked it. zero psi. Then I swapped the FPR and the A/C clutch relay since they appear to be the same part. zero psi.

I also read where I should hear the fuel pump running if there is zero psi and the ignition switch is ON. I heard nothing.

Then I switched on-off-on just like you said. It didn't start.

I guess it's time to replace the whole fuel pump assembly? Or should I try to bypass the FPR or replace it and try again?
 
Just to eliminate easy possibilities first try swapping the ASD and fuel pump relays with other relays like the horn relay inside the Power Distribution Center. If they're the same size they're interchangeable.
 
Just to eliminate easy possibilities first try swapping the ASD and fuel pump relays with other relays like the horn relay inside the Power Distribution Center. If they're the same size they're interchangeable.

I swapped the shutdown relay and the fuel pump relays with others of the same type. Still no go. I guess I could pull the fuel pump assembly and check it manually to see if I can make it operate. Sounds like a fair bit of stinky work.
 
I've never had any luck taking the pressure at the testing port (always zero). I've always had to check the pressure with the gauge in-line right before the rail, just something to keep into consideration before dropping the fuel tank.
 
I've never had any luck taking the pressure at the testing port (always zero). I've always had to check the pressure with the gauge in-line right before the rail, just something to keep into consideration before dropping the fuel tank.
Never heard of the factory Schrader valve on the fuel rail not giving a precise pressure.
 
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Never heard of the factory Schrader valve on the fuel rail not giving a precise pressure.

I refused to believe the fuel pump could go bad right after trying to resolve a P0505. So, as a precaution, I removed the needle from the valve and retested the pressure. Still zero.

From the videos I watched, it seems like I should have heard the fuel pump motor if there's zero psi. I'm new at all things Jeep so I'm willing to question every little gray cell in my head.

I feel like I need to see 12 volts at the pump's wiring harness before I drop the tank to see why the pump's not on. I think I saw the connector near the top front of the tank.
 
I've never had any luck taking the pressure at the testing port (always zero).

Is the cap on that test port? If not perhaps it's full of junk?

Also...I have an OTC fuel pressure gauge and there's this stupid brass T that sits inside the fitting and engages the valve...it falls out ALL the fing time.

-Mac
 
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Is the cap on that test port? If not perhaps it's full of junk?

Also...I have an OTC fuel pressure gauge and there's this stupid brass T that sits inside the fitting and engages the valve...it falls out ALL the fing time.

-Mac

No idea now since the TJ is on its second engine swap (LS and now TDI). I just remember that being an issue when the 4.0L was in there.
 
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I refused to believe the fuel pump could go bad right after trying to resolve a P0505. So, as a precaution, I removed the needle from the valve and retested the pressure. Still zero.

From the videos I watched, it seems like I should have heard the fuel pump motor if there's zero psi. I'm new at all things Jeep so I'm willing to question every little gray cell in my head.

I feel like I need to see 12 volts at the pump's wiring harness before I drop the tank to see why the pump's not on. I think I saw the connector near the top front of the tank.

Where is the gauge tester from? if the T inside is seized/missing/too short like @macleanflood said it will always read zero since it won't engage the schrader valve.
 
All depends on what gauge you use I guess. Cheap Amazon ones vs Part Store Rentals vs nice expensive ones. Could also be a one-off 🤷‍♂️

The gauge is an Evertough 67091 that I'm "renting" from O'Reilly. But I figure I'm good to go, even if it is a cheap gauge, if I first remove the needle from the valve. I tested with the needle in place and with it removed with the same results. Zero psi.

This a link to what looks like the thing I rented.

https://www.ebay.com/itm/2562677138...pid=5337789113&customid=&toolid=10001&mkevt=1
All depends on what gauge you use I guess. Cheap Amazon ones vs Part Store Rentals vs nice expensive ones. Could also be a one-off 🤷‍♂️

It's a EverTough 67091 that I rented from O'Reilly. I tried it with and without the needle in the valve. Zero psi.
 
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The gauge is an Evertough 67091 that I'm "renting" from O'Reilly. But I figure I'm good to go, even if it is a cheap gauge, if I first remove the needle from the valve. I tested with the needle in place and with it removed with the same results. Zero psi.

This a link to what looks like the thing I rented.

https://www.ebay.com/itm/2562677138...pid=5337789113&customid=&toolid=10001&mkevt=1


It's a EverTough 67091 that I rented from O'Reilly. I tried it with and without the needle in the valve. Zero psi.

Yeah those are usually hit or miss since they're used and abused. I know it's a pain but try and test for the pressure with the gauge in line. I'm also a believer that your fuel pump wouldn't go bad after trying to fix your P0505 code.

General gist of what you have to do:


I think the part you have to screw to the testing port isn't engaging the schrader valve, that's why you're seeing the zero reading.
 
This site contains affiliate links for which Jeep Wrangler TJ Forum may be compensated.
So this is a diesel VW TDI swapped TJ... we're not talking about the 4.0?

Getting confused...but then you wouldn't have gotten that code...so probably never mind and continue on testing...

-Mac
 
<aside>Needed more privacy so I had to pull the Jeep up (yes, uphill) into the garage. Love my neighbors too and they don't want to see me on the ground under a car.</aside>

I disconnected the fuel pump's wiring harness and identified the ground. Then I turned the ignition switch to ON and measured 12V across two pairs of pins. Attached is a picture of the harness and I've labeled 6 pins. Ground is pin 3. I measured 12V across pin 1 and 3 and 12V across pin 6 and 3. With the ignition switch in the OFF position, I think I measured some millivolts across pins 1 and 3 but because my tester doesn't measure millivolts I can't be too sure of the measurement.

Since I couldn't hear the pump's motor turning with the ignition on and I'm still getting 0 psi at the fuel rail, I figure it's time to drop the tank and bench test the pump.

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