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Discussion Starter #1
Hi there.
I changed the fuel filter on my 3.2 v6 last night. Now it takes longer to start.
Any ideas?
Air in fuel line? How do i bleed this?
Thanks very much.
Ben.
 

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Try charging your battery, just to rule it out.


I had changed the fuel filter in my 3.0 TDI and didn't do a thing other than take the old filter out and drop the new one in and the motor never missed a beat.
 

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Discussion Starter #3
Thanks
I tried charging the battery but it did not help

I am thinking an O-ring in one of the fuel line quick connects is letting in air and I am loosing fuel pressure.

Once driving it is fine. Just takes longer to start and fire up.

Has anyone else had trouble with the fuel line connections? Any advice?

Thanks.
 

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Thanks
I tried charging the battery but it did not help

I am thinking an O-ring in one of the fuel line quick connects is letting in air and I am loosing fuel pressure.

Once driving it is fine. Just takes longer to start and fire up.

Has anyone else had trouble with the fuel line connections? Any advice?

Thanks.
Seems like you have a slow priming issue. Once the car has started the other pump on drivers side provides low pressure fuel to the high pressure fuel pump on the block by the rail for the injectors .

I would open it back up and check all the connectors and wires. Sure you connected wires properly? Pull on the connectors to see they are locked down. They are push pull and need to make sure they are firmly connected. Would also check and make sure O ring below the flange is sitting properly and not pushed down into tank. If the O ring is seated properly the flange is easy to lock down and sits flush. Never have heard about bleeding air out of the system. Pump is a suction from the bottom so should not be any air in the line just fuel unless tank was very low or empty.
 

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make sure the filter is installed correctly. Some of them have thermostats in them that will allow full flow in one direction but only minimal reverse flow. Installing in reverse starves the fuel supply.

Other than that, check the intank pump.
 

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Discussion Starter #6
Thanks for the suggestions. I pulled it all apart again and found the following :

1. Fuel Filter O-ring was incorrectly installed. It's very hard to install. I guess that's why they sell it as part of the fuel flange.
I used the new top half of the fuel flange as it fitted the o-ring a bit better.

2. Bottom outlet of fuel flange has been previously modified with a hose clamp, probably because they did not want to disconnect the hose on the other side of the tank. So I retightened it.

See picture below of what happened.

All good now!!
 

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Thanks for the suggestions. I pulled it all apart again and found the following :

1. Fuel Filter O-ring was incorrectly installed. It's very hard to install. I guess that's why they sell it as part of the fuel flange.
I used the new top half of the fuel flange as it fitted the o-ring a bit better.

2. Bottom outlet of fuel flange has been previously modified with a hose clamp, probably because they did not want to disconnect the hose on the other side of the tank. So I retightened it.

See picture below of what happened.

All good now!!
Glad to hear. I just bought a new filter flange assembly rather than replace the filter. Next time may just change the filter as it is less costly. Previous filter lasted ten years (it was filthy/black). Running the line to the other side is not a big deal, but have heard others just cut and hose clamp, but I did not trust using a hose clamp.
 

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Discussion Starter #9
Hi.

I just had timing chain done and was trying to improve "cranking time to start" as my other car starts straight away, plus i didn't know if it has been done before.

The only reason or symptoms from reading the forum is people trying to address driveability and starting issues.

VW say it's life long filter but when i pulled mine out it was covered in black oily substance. I'm glad I changed it and now i know it's been done.

Apologies for the long reply. I hope i haven't put you to sleep 😉
Cheers.
 

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Driveability problem particularly normal at slower speeds but bogs on acceleration would be a typical symptom. It is interesting to learn starting could be another.

Looks like the filter should be considered a routine maintenance item. Thanks for the picture and detailed explanation. :D
 

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Hi.

I just had timing chain done and was trying to improve "cranking time to start" as my other car starts straight away, plus i didn't know if it has been done before.

The only reason or symptoms from reading the forum is people trying to address driveability and starting issues.

VW say it's life long filter but when i pulled mine out it was covered in black oily substance. I'm glad I changed it and now i know it's been done.

Apologies for the long reply. I hope i haven't put you to sleep dde09
Cheers.
Did changing the filter improve cranking time? If not you might want to pull and clean the camshaft sensors and crank sensors and clear the crude off the magnets. Clean sensors can improve cranking time.
 

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Not really. Just back to what it was.
I might try that next.
The sensors are what help the car crank fast. They tell the ECU which piston is at TDC and fire it first. If either of the camshaft sensors go bad car will take much longer to crank. If both camshaft sensors go out the ECU will use the crankshaft sensor and it will take a very long time to crank. If the crankshaft sensor goes out the car will never start and die immediately if running.
 

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With 100K on the egg, decided to clean the fuel filter. Two months ago I got home after a 2 hour drive at high speed, unpacked the car and when starting up, car would barely run. Turn off and restarted just fine. So with time on my hands, I wanted to check the system out. First of all I can’t believe the fuel rack doesn’t have a fuel tap. So with a homemade setup checked fuel pressure. Noted items:
1. Opening the driver’s door, primer pump comes on for a short time. Fuel pressure 60 psi. Pressure is checked in. No pressure drop noted, so check valve appears to be working.
2. Start engine and pressure is around 62 psi. To determine if fuel filter is restricting flow, the gauge setup has a pressure release button. Pushing the button, fuel filled a 12 oz. bottle in no time. I figured there’s no way with the engine at full throttle it could use this amount of fuel. Pressure drop was around 3-4 psi.
On other threads, I’ve noted that fuel pressure should be around 55 psi. So do I have a problem here?
So with this known, jumped into filter removal. With filter removed, fuel filter with 100K. Used two cans of carburetor cleaner.
With everything installed, couldn’t get any pressure and started asking myself what happened but with benb2376 post’s “lessons learned” when installing the O-ring/cap I also rolled the O-ring off the seated position. So note: lubricate the O-ring and cap and when you get the cap seated hold firmly until you get a couple of screws installed. Due to the filter spring, item 10 on benb2376 attachment, the spring will want to move the cap thus dislodge the O-ring. So with everything back together, opened /closed driver’s door. Thought I heard the pump but had no pressure. Closed door and went and got a drink, cause I needed one. Came back opened door and got 40 psi. before the pump shut off. Started engine and pressure went to 62 psi. Hit the pressure release button on the gauge and got a little air. With everything back together, I drove the car to work today.
Another thing I learned is when the engine is cold it runs at a higher RPM and drops when engine is warm. What is noted is that the fuel pressure stays the same. On past cars the fuel regulator would lower fuel pressure during warm up and return to a higher pressure after it’s warmed up. So again do I have an issue with the regulator?

Anyway attached some pictures.

 

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With 100K on the egg, decided to clean the fuel filter. Two months ago I got home after a 2 hour drive at high speed, unpacked the car and when starting up, car would barely run. Turn off and restarted just fine. So with time on my hands, I wanted to check the system out. First of all I can’t believe the fuel rack doesn’t have a fuel tap. So with a homemade setup checked fuel pressure. Noted items:
1. Opening the driver’s door, primer pump comes on for a short time. Fuel pressure 60 psi. Pressure is checked in. No pressure drop noted, so check valve appears to be working.
2. Start engine and pressure is around 62 psi. To determine if fuel filter is restricting flow, the gauge setup has a pressure release button. Pushing the button, fuel filled a 12 oz. bottle in no time. I figured there’s no way with the engine at full throttle it could use this amount of fuel. Pressure drop was around 3-4 psi.
On other threads, I’ve noted that fuel pressure should be around 55 psi. So do I have a problem here?
So with this known, jumped into filter removal. With filter removed, fuel filter with 100K. Used two cans of carburetor cleaner.
With everything installed, couldn’t get any pressure and started asking myself what happened but with benb2376 post’s “lessons learned” when installing the O-ring/cap I also rolled the O-ring off the seated position. So note: lubricate the O-ring and cap and when you get the cap seated hold firmly until you get a couple of screws installed. Due to the filter spring, item 10 on benb2376 attachment, the spring will want to move the cap thus dislodge the O-ring. So with everything back together, opened /closed driver’s door. Thought I heard the pump but had no pressure. Closed door and went and got a drink, cause I needed one. Came back opened door and got 40 psi. before the pump shut off. Started engine and pressure went to 62 psi. Hit the pressure release button on the gauge and got a little air. With everything back together, I drove the car to work today.
Another thing I learned is when the engine is cold it runs at a higher RPM and drops when engine is warm. What is noted is that the fuel pressure stays the same. On past cars the fuel regulator would lower fuel pressure during warm up and return to a higher pressure after it’s warmed up. So again do I have an issue with the regulator?
Anyway attached some pictures.
Flow from the pumps is only low pressure fuel to the high pressure pump on the block which increases fuel pressure to less than 1,750 psi going to the fuel rail for the injectors. Doubt you have an issue with the low pressure regulator above the passenger side pump. If car runs ok would not worry about it. Check the pressure again it probably is higher than the 40psi you recorded which may have been low due to air in the low pressure system.
 

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Discussion Starter #16
ssicbx

Great report and photos. Like G6 said it would be good to repeat.

Even if you repeat 3 or 4 times and get the average. Data is king!

Regards
Ben
 

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G6, don't know about the 1,750 psi. You think the pump could make that kind of pressure? As to the 40 psi. this was with the inital start up, with air in the system. As to the amount of time the primer pump runs, I think this based on time instead of pressure.
Benb, where do you live in Australia? I used to work out of Perth. Long flight!
 

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G6, don't know about the 1,750 psi. You think the pump could make that kind of pressure? As to the 40 psi. this was with the inital start up, with air in the system. As to the amount of time the primer pump runs, I think this based on time instead of pressure.
Benb, where do you live in Australia? I used to work out of Perth. Long flight!
Sorry. The pressure release valve for the high pressure pump will activate if rail pressure exceeds 1,740 psi. Yes the high pressure pump can produce that kind of pressure. Would have to for the injectors to Inject vaporized fuel into the combustion chamber. Should have 800cm fuel with 15 seconds of flow from low pressure pumps.
 

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G6, don't know about the 1,750 psi. You think the pump could make that kind of pressure? As to the 40 psi. this was with the inital start up, with air in the system. As to the amount of time the primer pump runs, I think this based on time instead of pressure.
Benb, where do you live in Australia? I used to work out of Perth. Long flight!
The high pressure fuel pump is piston driven and generally operates at 1,595 psi.
 
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