[tharlan505]

I just made better jumper wires and forced both low pressure fuel pumps to run.

I rented a fuel system diagnostic kit from AutoZone. I connected to the low pressure fuel line under the hood. (connection located at top edge of fire wall in center of engine bay).

I used the bleed valve on fuel pressure gauge to purge any air in the system. I let it run for about 45 seconds to a minute. I verified that both fuel pumps were running the whole time. I released the bleed valve to allow pressure to build, even though at no time did any fuel come from the bleed valve. Never did any fuel reach the low pressure fuel line, at the coupler just before the high pressure fuel pump located in the engine head (nor my diagnostic fuel gauge).

So, that would mean no fuel is being delivered to the high pressure fuel pump, right?

 

[tharlan505]

I just had both low pressure fuel pumps replaced by a mechanic about 500 miles (only one fuel fill-up) ago.

What could be the issue here?

 

[G6mdxvct]

I just made better jumper wires and forced both low pressure fuel pumps to run.

I rented a fuel system diagnostic kit from AutoZone. I connected to the low pressure fuel line under the hood. (connection located at top edge of fire wall in center of engine bay).

I used the bleed valve on fuel pressure gauge to purge any air in the system. I let it run for about 45 seconds to a minute. I verified that both fuel pumps were running the whole time. I released the bleed valve to allow pressure to build, even though at no time did any fuel come from the bleed valve. Never did any fuel reach the low pressure fuel line (just before the high pressure fuel pump located in the engine head).

So, that would mean no fuel is being delivered to the high pressure fuel pump, right?

That would be my opinion. Find it hard to believe both pumps are faulty. You should get fuel to the high pressure pump. Perhaps the pressure regulator assembly flange above the passenger pump is faulty. Could have some blockage in the filter but does not seem likely. Pretty hard to connect the lines wrong. Can't have a leak or you would know/smell. The pumps when powered will hum, but still might not properly suction fuel so noise is not necessarily proper operation.

I am not aware of any function that prevents fuel flow from operating pumps to reach HP pump. Pretty certain a bad pressure regulator can keep pressure from achieving 2 bar. Think low pressure system's operating pressure has to be between 2and 5 bar.

You could pull one of the pumps, get a mop bucket set the pump in the bucket, put about 3 inches of water in the bucket, let lines hang down, attach a battery source to the connector and you should get flow from two lines or one can't recall. You can use an RC car battery. If you feel comfortable putting fuel in the bucket won't have to let pump dry before reinstalling. Have to be careful, no sparks from battery source. I just use very long leads and never stand over bucket. A fully charged RC battery should produce good flow. No flow, bad pump. Would do drivers pump first however you could just have a pressure issue.

I would replace the pressure assembly valve on the assumption pumps are OK. Would also make sure tiny electrical connector to fuel filter flange and pressure flange(inside tank) are connected to correct terminals.

 

[tharlan505]

Thanks for jumping in G6,

Is is possible that I could have a leak in a hose within the fuel tank?

I'll check connection under driver side (USA) fuel pump flange.
I might try the RC battery (my 1/18 scale rc uses 7.? volts, my drill battery uses 18 v), but I paid a mechanic (one of the only two times in my life) to replace both fuel pumps in the tank, so I might have it towed back to him.

Like you said: Perhaps the pressure regulator assembly flange above the passenger pump is faulty.

How would I know if the pressure regular assembly flange is bad?

 

[tharlan505]

I'll check hose connections within fuel tank again tomorrow.

And yes, I would certainly notice a drip of fuel in the bin or under the vehicle.

 

[benb2376]

I'm working on it right now. Please chime in if you have any other advice.

I just found this:

http://www.waynet.com.cn/r36.pdf


Excellent resource.

Just a suggestion. A summary of events might help everyone understand your Touareg's issues to date.

Can you please list out the sequence of repairs that have been done on the vehicle prior to this issue?
ie.
1 - Replace fuel pumps . Who : Mechanic . When : 2 weeks ago
2 - Checked relay xx. Who : Me . When : yesterday

Try to write a list of YES/NO items some you can check things off as you complete them. This will try to keep you sane and also help others understand what your up to.

So if the pumps were replaced do you know if the flanges have as well? That's the tank "cap" with the filter on it (LHS) and the regulator (RHS) ?

Maybe the filter has not been changed and it is blocked or some "gunk" from the pump line has lodged itself in the filter.

You could try washing out the filter with petrol/gasoline and re-installing .

Please don't take this the wrong way. It's only a suggestions.

Good luck!!

 

[SamT]

If you can hear the pumps buzzing and no fuel is coming out of the bleeder valve on the fuel pressure gauge, then no fuel is going to the high pressure pump.

I think you need to have the two fuel pumps, particularly the pipe connections between the two looked at again. Maybe the pipes came loose.

 

[tharlan505]

No Problem benb2376,

I did the work unless otherwise noted.

Summary of events:

• 
  I replaced all spark plugs and coils about six months ago.

• Checked air filter about 500 miles ago.(it was clean).

• After about 1,500 miles of driving (about 500 miles ago), engine performance was operationg perfectly. I refueled (with premium octane) from 3/16th's to full tank of gas. The touareg would start, but only run for 30 seconds, then die. I had to leave the touareg at the gas pump and get a tow truck the next day. I had it towed to my local euro mechanic.

• We decided to replace both fuel pumps and their seals.

• I drove the touareg, it was working perfectly after the new fuel pumps (for about 500 miles).

• when fuel was low, I refueled again with Premium octane like always. The current issue surfaced when it got to about 3/8th's of a tank.

• I drove to work, at night, in perfect weather (about 70ºF, clear skies) to check on something. When I arrived at the work site, I park (with engine running) get out and open rear glass to get my keys to open the gate. I open the rear glass and a few seconds later, while I'm fishing around in the back, The engine dies. Radio and lights stay on, just like clicking the key from running to the "on" position, but I didn't touch anything. The touareg would crank forever and not start after that. A buddy came to help out, and we put more gas in it, and after no start, we towed it about 300 feet to under an awning of the worksite and it has been there undercover ever since. That was about 5 or 6 weeks ago.

• Since then, I have kept battery on float charger, and I have replaced the crankshaft sensor twice, just for good measure.

• Now we know it is not getting gas to the High pressure fuel pump for some unknown reason.

 

[tharlan505]

If you can hear the pumps buzzing and no fuel is coming out of the bleeder valve on the fuel pressure gauge, then no fuel is going to the high pressure pump.

I think you need to have the two fuel pumps, particularly the pipe connections between the two looked at again. Maybe the pipes came loose.

I think you are right. I'll check the hose connections within the fuel tank tomorrow

(and I will likely bring the Touareg back to the mechanic (who installed the fuel pumps), if we can't solve this issue in the next two days.

 

[pjod]

tharlan,
I may be off base with this suggestion but here goes anyway.

you have had a problem where no fuel is coming out the high pressure pumps and had them replaced.

After working for a while the problem has reoccurred.

You are now looking at connections to the pump, and within the tank itself as well as for split piping.

Just a thought that maybe there is something restricting the fuel flow that builds up over a bit of time. Perhaps the pipes are blocking?

Seems to me that perhaps there could be some grunge or grit in the tank that gums up the fuel flow, and that it took a bit of time to restrict the aperture after you replaced pumps to cause the problem to reoccur.

Maybe you need to consider an empty and thorough clean of the tank and replacement with fresh known good fuel. if fuel is dirty then perhaps the fuel lines themselves need to be looked at.

We don't get the cold weather here that you get, and hence don't generally have winter fuel to worry about (37.8 C here at the moment - near enough to 100F) but as I understand it that perhaps may have contributed to your problem with poor fuel for the temps you are in.

May well be off base, but if going into the tank have a look at the fuel quality perhaps while you are there (signs of dirt etc).

Hope you get this sorted soon, and hope y comments aren't too off base
Cheers

 

[G6mdxvct]

I think you are right. I'll check the hose connections within the fuel tank tomorrow

(and I will likely bring the Touareg back to the mechanic (who installed the fuel pumps), if we can't solve this issue in the next two days.

My recollection is that one of the lines from the drivers side fuel pump connects to the underside of the pressure regulator flange on the opposite side and one line connects to a line from the passenger pump. Not certain how to determine the pressure regulator is bad. Sorry. If the pumps operate correctly there is either a blockage or pressure issue. A clogged filter could be an issue, however seems you would get flow from the passenger pump when operated independently.

Taking it back to whomever did the pumps is not a bad idea. Something is not working properly in the system. The filter screen on the bottom of the fuel pumps and screens inside the pump along the pump sleeve are so fine it is doubtful anything could get into the system and clog a line that was sucked up by the pumps.

My bet is the drivers side pump flow/ pressure is to low and perhaps passenger pump too. Not certain what pumps were installed but there are crap ones out there. I have had good luck with VDO pumps, and assembly flanges. I replaced everything when I did my pumps.

If you disconnect the fuel line on the top of pressure regulator assembly side does fuel spill out? The system should be under pressure even when not running as there is a pressure retention valve and relief valve.

 

[G6mdxvct]

I think you are right. I'll check the hose connections within the fuel tank tomorrow

(and I will likely bring the Touareg back to the mechanic (who installed the fuel pumps), if we can't solve this issue in the next two days.

There is a line from the passenger side that connects to a line from the other pump. It is an inline connection, push in tab then push pull like all the others. Would check that connection first. The others could be a problem but are line to nipple connections and once pushed on past the locking tab usually stay put. Usually if a connector is loose the pressure is enough to push apart, however you never know. Even the inline connector has a nipple and locking tab. Would not hurt to disconnect and reconnect the lines, pulling on them once locked on firmly to make sure.

You could test the pump in the tank by hooking a battery to the electrical terminals on the assembly flange. Any DC battery would do. I use 9v RC battery. You could unhook one of the lines from the pump, power the pump and see if there is flow. Have to be careful around fuel- no sparks.

 

[tharlan505]

I'm going to check all the hose connections after lunch, Thank G6. Good advice.

I'm posting some of the pages that I found interesting (as attachments, I couldn't figure out how to insert as PDF's):

 

[tharlan505]

Also, This video that is for a V8 engine.

www.youtube.com/watch?v=ZVBaH2jsPg4

 

[tharlan505]

SO, I connected a clear flexible hose to one port at a time on top of the Passenger side fuel pump flange and jumped the relay to make it run, but nothing came out. it was gurgling, and it's little motor was running, but no fuel left the flange.

I called my mechanic, who replaced the pumps about 500 miles ago and I will be taking it to him, as it's possible he might fix it for free or for very little if it had something to do with his work.

 

[G6mdxvct]

SO, I connected a clear flexible hose to one port at a time on top of the Passenger side fuel pump flange and jumped the relay to make it run, but nothing came out. it was gurgling, and it's little motor was running, but no fuel left the flange.

I called my mechanic, who replaced the pumps about 500 miles ago and I will be taking it to him, as it's possible he might fix it for free or for very little if it had something to do with his work.

Have him replace with VDO pumps, both sides. Does not matter if Porsche cayenne or VW same pump. Both of mine said cayenne on the box. I would spend the money and put in new assembly flanges for the filter and pressure regulator. Think your previous post indicated only the seals were replaced?

Looks like correcting this will resolve your problems.

 

[tharlan505]

G6,

That was perfect advice, and perfect timing!

Sorry, I've been gone so long from the forum, just busy.
I read your last post just as the tow truck was pulling into my mechanic's shop. I asked him to check the regulator in the flange on the passenger side USA.

He did use the correct VDO pumps on both sides. It turns out the techs that worked on it, "may or may not have" connected one of the hoses deep inside the fuel tank. (must not have pushed the quick connect on all the way). Mechanic said he wrapped wire around it this time to keep it on. That docent sound great, I hope he used stainless or aluminum. It runs fine now.

 

[G6mdxvct]

G6,

That was perfect advice, and perfect timing!

Sorry, I've been gone so long from the forum, just busy.
I read your last post just as the tow truck was pulling into my mechanic's shop. I asked him to check the regulator in the flange on the passenger side USA.

He did use the correct VDO pumps on both sides. It turns out the techs that worked on it, "may or may not have" connected one of the hoses deep inside the fuel tank. (must not have pushed the quick connect on all the way). Mechanic said he wrapped wire around it this time to keep it on. That docent sound great, I hope he used stainless or aluminum. It runs fine now.

Glad you got it squared away. I had similar frustrations working on my car and after awhile your patience wears thin.

I was just wondering about you this morning. Figured no news was good news. Always good to hear the outcome/ resolution.

 

[tharlan505]

The tow was $85, and I swapped out the crankshaft position sensor twice, so I spent about $300.

I now have two extra, perfectly good crank shaft position sensors, one was used, the other was not.

I'm planning to sell the Touareg. I'll try to post it in the Classifieds in the coming weeks. I have "for sale" signs in it now.

 

[G6mdxvct]

The tow was $85, and I swapped out the crankshaft position sensor twice, so I spent about $300.

I now have two extra, perfectly good crank shaft position sensors, one was used, the other was not.

I'm planning to sell the Touareg. I'll try to post it in the Classifieds in the coming weeks. I have "for sale" signs in it now.

Mine is paid for and plan on driving until it blows up or repair costs get outrageous. Not going to get enough for a ten year old car to make it worth while if i sell. Have been looking at the Porsche Macan, but not ready to commit to $70k. Baseline is $50k Nice car though, a little smaller than the touareg, same chasis as the Audi Q5. Would have to sell my GTI and wife's Tiguan which would not go over very well.