Possible lift pump problem?

[TwedA4]

Hi all,

my car has been playing up a little the last few weeks and i'm beginning to wonder if the limp pump in tank pump) is playing up.

it starts and idles fine, first turn of the key and starts on the button every time. runs ok but on a steady throttle then call for a little more power on a straight perhaps (not foot flat down) it kinda hicups then gets a move on. it doesnt splutter on or take ages to get up and go... its been doing this for a few weeks now and it's almost every day but only ever happens once.

and last week when i changed the fuel filter, i turned the ignition off and on a few times to prime the system and fill the new filter and i could hear something in the tank but it didn't sound normal. kind of like a kid sucking a straw of an empty juice carton, lol. the car started but then cut out and took an absolte age to get going again, and that was with turning the ignition off and back on to try prime it.

is there any way of testing the lift pump or would it show up on a scan as being at fault or anything? only reason i ask now is i have it booked in for a remap at unicorn motor developments and would like it to be tip top as it's quite a journey!


cheers.

 

[desertstorm]

It could be an issue with the fuel pump, they tend to be more noisy when less than 1/4 full as you can hear the returned fuel splashing in the tank.
In my 130 TDI passat I could get the in tank pump running continuously and it would run around 1.3-1.4 Litres per minute after I ran through some fuel conditioner. Have a look at my build thread here.

http://www.ukpassats.co.uk/phpbb/viewtopic.php?f=5&t=56110&start=150

If you can locate the fuel pump relay, take the cover off, you can make the pump run when the engine isn't by closing the relay contact. Pull the fuel pipe off the fuel filter and put into a measured jug.Run the pump for 30S and see how much fuel comes through.

Check the coolant temp sesnor is good as well. connect up VCDS and make sure the engine temp looks to be reported correctly. The CTS has 2 sensors in it, 1 feeds the gauge the other the ECU.

Also could be signs of a failing MAF, you really need VCDS to check the MAF and CTS.
You won't be dissapointed with a remap from RIck.

Karl.

 

[TwedA4]

Thanks Karl. i remember seeing something like this in your passat thread a few months back so i'll try some conditioning stuff in the tank tomorrow. failing that, looks like i'll be getting dirt this weekend!

no one in my area at short notice with VCDS unfortunately so will see how i get on.

yeah, i was very impressed with what rick done for your motors, especially the a4, that's one main reason i've gone for him.


cheers

 

[desertstorm]

Rick only mapped my A4, I did most of the mapping on the Passat myself. I am sure Rick would have done a better job though.

 

[TwedA4]

oh, in that case... cracking job pal! lol

is the lift pump under the floor in the boot or under the seats?

 

[desertstorm]

In an Avant it's under the load carpet in the boot and in a saloon under the rear seats I believe.

http://www.audi-sport.net/xf/threads/please-help-fuel-pump-location.122119/

Karl.

 

[Darran]

Have you checked the throttle body for gunk ?