Username or Email Address
Do you already have an account?
Forgot your password?
  • Log in or Sign up

    VWVortex


    Results 1 to 4 of 4

    Thread: CIS question, weak power on cold start

    1. Junior Member V-Duuber's Avatar
      Join Date
      Mar 31st, 2007
      Location
      Columbus/Atlanta GA
      Posts
      94
      Vehicles
      87 Jetta 8v , 2005 Jetta 2.5
      08-12-2012 02:45 PM #1
      Here's my symptoms, when the car first starts, the initial run through 1st and 2nd gear are very weak, almost as if the engine is getting flooded with too much fuel. Once you get to 3rd, it never happens again in 1st and 2nd. Revving up past 2000 will solve the problem before moving as well. Another issue, if my fuel is less than 1/4th tank, it will start to cut out and get little to no power and just stall itself. Also when it does this, the fuel pump will whine pretty loud. I'm new to CIS and any help or recommendations on things to check would be most appreciated, thank you in advance.

    2. Member
      Join Date
      Aug 14th, 2005
      Location
      Germany
      Posts
      2,272
      08-13-2012 03:51 AM #2
      You have 2 fuel pumps in that car. One is the "main" feed pump, also called the under car pump or whatever, and a small transfer pump in the fuel tank. From what you say I would replace the transfer pump ASAP and hope that no real damage is done to the main pump ($). The transfer pump feeds the main pump and if it fails then only physics (gravity) will supply the main pump any fuel. Problem is that the main pump does a bad job at drawing fuel from the tank, not designed to do it, and when under a half/quarter tank not much fuel is pushed up and out the fuel tank. This causes the main to starve for fuel and whine like a stuck pig, OK not exactly. That noise is your main pump telling you is is not being lubricated, more or less.

    3. Junior Member V-Duuber's Avatar
      Join Date
      Mar 31st, 2007
      Location
      Columbus/Atlanta GA
      Posts
      94
      Vehicles
      87 Jetta 8v , 2005 Jetta 2.5
      08-13-2012 06:21 PM #3
      awesome, thank you so much for the info. Is the in tank like the main, if it fail it fails or can it slowly go out? I guess what I'm asking that for is if you can test to see if it actually working by listening/feeling it?

    4. Member
      Join Date
      Aug 14th, 2005
      Location
      Germany
      Posts
      2,272
      08-14-2012 03:46 AM #4
      It is not the same as the main pump except that it is also electric. It is refered to as a low pressure high volume pump and is much smaller. It hangs down on a hose from the fuel level sender mounted on the top of the tank. If yo remove the mat in the trunk you will see a round metal cover, near the right rear wheelwell, that has three sheetmetal screws securing it in place. Under that cover is the fuel level sender and electrical connection/hoses. Testing can be done there, like checking for power, listening if it is running (long screwdriver to your ear is best), or doing a flow test. It should all be in the repair manual that you have.

      By the way, they are cheap and replacing it is about as easy as doing the testing.

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •