Please help! 84vw running rough

Not being as well versed as in Diesels or Digifant, CIS has issues with the ait control plate that can become "Sticky", and I have heard of similar issues with it when this happens. The issue is that Fuel that is allowed to evaporate in a system can lacquer things up, that you have tun new gas in it can cause things to break free and clog up other things.

Is this an early 84, or 84.5? as the difference is that the 84 had a 10 gallon tank and a full sized spare tire. Where as the 84.5 has a 13 gallon tank and a space saver spare tire.

Why? because the 84.5 has 3 fuel pump, one external and one internal? So let me ask if the fuel pumps whine? that is can you hear them?
The issues are that when the in-tank pump becomes fouled, it can cause the fuel form the tank to not be delivered to the Primary fuel pump effectively starving the primary so it has to work harder and whines about it. The in-tank pump can go bad, and or the connection hose that holds the fuel pump to the sending unit can break or hole. So if you have an 84.5 you may want to pull the inspection plate and remove the sending unit to take a look inside your tank.
not only to validate that your pump is in good shape, but to see if there is any rust or things in your tank.

WARNING you have to have 3/4 or less of fuel in the tank to pull the sender, and you have to disconnect the battery....
in the FAQ's or DIY sections I have a How do I do that there.

Well sending units are the unobtainium, or hens teeth.
I have heard of Skoda or a Polo as a replacement, the issue is that the Jack for the sending plug is straight up and down, not as a 90 degree.
If your mechanism is rusty you can clean it up and have it re-anodized. The Tank is another issue as well as you have to get it cleaned or de-rusticated/ replaced.

If you plan on dropping your tank, then you have to lower the rear axle about 6 inches for the tank to clear, and I would strongly urge you to clean the mounting studs and bolts of rust and crud with a wire brush, and start soaking them in PB-Blaster, use only an air impact and a 6pt socket on them as if you use a socket and a breaker bar Torque shear of the studs is probably going to happen then you are worse for the wear.

Be mindful of your rubber connect lines on the rear axle for the Brakes as well.
I would remove your main pump and back flush the fuel lines from the Filter back as I imagine it is chuck full of particulates.

Here’s the one I ended up buying, hopefully it will work out:

https://www.ebay.com/itm/Brand-New-...dMAAOSwoZlb7Wbo:sc:USPSFirstClass!95688!US!-1

I also started the process of cleaning up the sending unit and am pretty happy with the results so far. I bought some rust remover and it is working wonders. Quick question about the wiring, is it supposed to have bare wires exposed? Not super well versed with electrical stuff but it seems weird that there are bare wires submerged in fuel.

Here’s some pics before I started cleaning it up:

WOW that is some Crusty Stuff. I have seen folks Soak the Crusty parts in Vinegar and let it work to remove Rust....
That Interconnect hose is really bad, going back you need to use Submersible Fuel Injection hose. I can imagine what the inside of the tank and filler neck look like as well.

I forgot to link the HOW do I change my in-tank pump out.
https://volkswagenownersclub.com/vw...1993-mk1-How-to-change-your-in-tank-fuel-pump

Yes that is the correct in-tank pump, and years ago, O'Reilly's in Mobile Ala wanted 120 bucks for it....(usually costs me 50...as I was 300 miles from home, I found a OLD Beetle shop that sold me one for 38... )

Bare Joints submerged in fuel? Sure they are Bare... But you have to remember that your sending unit is a Rheostat, that is varying the resistance of ground to the Fuel gauge and at the same time is sending the +12, and Ground to the pump, and that it isn't shorting out. Vary tried and true method of these Critters.

Once you get the thing a little more cleaned, you can "Carefully as they can break" Pry the fingers off the cover, and remove it, be-warned you have a Finger wiper and Spring on the flat shaft so take good care to remove it as that spring can fly off.





I have a pair of end nipper wire cutters that are great for bending those tabs you just have to remember that older metal like that is
very brittle and rusty ones more prone to breakage...so take extreme care.





The Plastic on your Circuit Board may be very Brittle, so take Extreme Care in Trying to remove it....(READ BRITTLE PLASTIC DOESN'T Bend it BREAKS)

Using a 3 foot piece of String to hold the filter in place while you screw and Man-handle the thing back in prevents the Filter from falling off.






When you have it about ready to re-lock, just cut the string and pull on the Knotted side to remove.

PS: When using Photo-bucket, use the IMG link in a Thread, not the email or direct link, I have edited your post to reflect the change and display the photo instead of the link.

Imgur is nicer hosting site, and for them you use the "BB" link to have Photos Show up.

Again, thank you for the help. I truly appreciate your help. The product I bought to clean the rust from the sending unit worked quite well. Here’s the before and after:

cajun100 said:

Wow -- my second post and it might actually be helpful !!!!
Be aware there is on most 1984-85 convertibles a small "storage tank" made of plastic, that acts in concert with the fuel tank and pumps to avoid fuel "starvation" -- for the hard cornering crowd. I spent 3 months on internet everywhere trying to get a replacement for mine that had cracked. It is simply not available at this point.
I used various adhesives to fix the cracked inlet tube until I found one that worked. So far.

Click to expand...

That is called a Filter, some over in the uk say Sump or Swirl pot, but it is officially a filter.
Clipped to the passenger side of the tank on the seam.




Also the OP need to know that the fuel pump attachment is submersible fuel hose, and that on the other pipe there is a length of hose on it as well so it can return gas to the tank and away from the inlet of the pump.

I would change the primary filter.