fuel system questions

[Mr.Matty]

Hello all, I'm new to this site as well as a newbie Audi owner. Recently bought a 96 A4 non quatro v6. Starting acting rough at start in the AM now it won't start. Fuel pump doesn't prime when I cycle the Key. Fuse is good no power at the fuse for the fuel pump unless the engine is cranking... Normal? I replaced the relay with no change. Book says the fuel pump access is under the back seat, but I don't see it there. Any help would be greatly appreciated.

 

[Bradderz_1988]

Its in the boot the access under the boot carpet behind the o/s/r seat !! 3 phillips screws and its out, also i would think that the fuel pump primes for seconds then has a constant live when engine is running easy enough job, flat head screwdriver and hammer to knock the ring loose and screw off then get a long spanner 24mm or bigger lock it in the pump housing and twist the spanner in a anti clockwise direction to unlock it from the bottom of the tank.

 

[Bradderz_1988]

Before you do that check for voltage at the connector whilst someone flicks the ignition on and off dont no which pin is the feed but you should see 12v on one of them.

 

[Mr.Matty]

Awesome, i will give it a try tomorrow. could the pump access possible be in the trunk? i pulled the rear seat bottom out and there is just rubber lining and 2 control modules. i swear everything i have gone to my repair manual (chilton) has been far from accurate.... I just want my baby back on the road!!!!! ha ha

any idea as to why i would not get a 12v (prime) to the pump at start of key cycle? my other vehicles always show a 12v (prime) at cycle. just wondering if it could be a faulty pressure switch in the fuel system or possible a faulty low oil pressure switch...

I'm extremely skilled in heavy duty diesel mechanics (my profession) but these things boggle my mind... guess i just havent spent enough time with this end of mechanics.

 

[Bradderz_1988]

Its in the boot behind the drivers rear seat easiest way would be to check for voltage at the pump if you havent then its probably the relay which is 287 iirc.

http://m.audiworld.com/picture.php?albumid=12130&pictureid=16455

 

[Mr.Matty]

thanks for all the informative info Bradderz. Much appreciated, I'll get into the issues over the weekend and hopefully have her back on the road.

 

[aragorn]

If theres 12v when cranking its not the relay.

Some ECU's simply dont prime. Given the 2.6 runs an ancient hitachi thing its entirely possible it just doesnt do it.

Does the pump actually run when cranking? Crack off the fuel union on the rail and see if you get fuel coming out when cranking the engine.

next step would be a fault code scan to ensure theres nothing obvious.

 

[Mr.Matty]

Thanks all. she is back on the road!!!!! It was the pump. after spending countless hours messing with the wiring i found out that my service manual (chilton) has a incorrect pin location drawing for the pins at the fuel pump plug.

Just some FYI's for anyone else...

-the system does send a 12v prime for approx 1.5 to 2 seconds.

-DO NOT TRUST CHILTON SERVICE MANUAL PIN LOCATIONS. (when i get home i will attach the correct pin locations and which pins to check the fuel level sensor and the fuel pump.

- the fuel pump not functioning will not throw a fault code.... i had already tried a scan tool hoping it would direct me down the proper path.

Thanks to the guys that offered the information. being that i'm a newbie all this stuff is new to me.... so far i really enjoy the car though.

hoping to start adding some mods to the car this summer... anyone have recomendations on what to start with?

 

[Bradderz_1988]

With it being a 96' the first thing i would be doing is a Facelift conversion and a nice set of shoes

glad you got it sorted pal mine went last month up near blackpool way when i was picking up my S4 rear bumper luckily seller had one and sorted it out with me and gave us the pump for free !!

 

[Mr.Matty]

What is the face lift conversion? I have read it all over Audi forums. I just put some 18"trw wheels on it with some jap spec nitto tires... Thanks to a large pothole!
That's awesome seller have you a fuel pump. What luck!!

 

[Bradderz_1988]

Full Facelift conversion - consists of front wings, bumpers and lights, centre dash and illuminated air vents and doors if you want the differant style door handles, scuttle panel and probably other stuff ive missed !!