Fuel starvation??

The main fuel pump is mounted under the chassis, so it can be heard. The transfer pump is in the tank. Both serve their purpose as noted by their designated names. There is a recirculation system in the fuel system returning fuel back to the tank. One originates from the transfer pump. The other originates from the main fuel pump.

The only change in frequency I normally hear day to day is when the idle is first increased to initiate the alternator output. The sound is coming from the main fuel pump, and this is normal.

My first move would be to flush the tank, examine the pickup and mounting area for debris. Dave

Change the transfer pump!!! They are relatively inexpensive and easy to change. ;-) Also I have found clogged (with debris) inlet pipes on the main fuel pump housings.

I think I will change the transfer pump first. It would make sense since it's the easiest to replace (and, I have two spares). I will check the tank for crap while it's out. I was just curious as to how strong that main pump was. I will post back with the results. Thanks guys, Rick

AFAIK the main pump is not designed to suck fuel, only pressurize it as it pushes the fuel through the system. Transfer pump pulls it from close to the bottom of the fuel tank and then pumps it to the main pump's housing.

If the transfer pump is not doing its job then the main pump whines and whines to you! lol

Are those spare T-pumps new or used? Since you have them.........change it out! ;-) You might find some engine power has come back too!

I think I will change the transfer pump first. It would make sense since it's the easiest to replace (and, I have two spares). I will check the tank for crap while it's out. I was just curious as to how strong that main pump was. I will post back with the results. Thanks guys, Rick

I think I will change the transfer pump first. It would make sense since it's the easiest to replace (and, I have two spares). I will check the tank for crap while it's out. I was just curious as to how strong that main pump was. I will post back with the results. Thanks guys, Rick

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If the vehicle has ever set a long time with minimum fuel in that tank, the whole inside could be going due to rust. Includes the transfer pump, the combination gas pickup and gas gauge sending unit, and the inside of the tank itself. Should be detectible by frequent fuel filter change requirements. Dave

Why not check the transfer pump before replacing it???? Just pull the output hose off the float unit and turn the key on.

I think I will change the transfer pump first. It would make sense since it's the easiest to replace (and, I have two spares). I will check the tank for crap while it's out. I was just curious as to how strong that main pump was. I will post back with the results. Thanks guys, Rick

Happy New Year! Turns out it is worse than expected. The fuel reservoir came apart at its seem. And was leaking gas the whole time. I'm lucky I noticed it, and it failed, in the driveway. So I dropped the old res and removed the lines. The fittings and metal parts have been reduced to dust. I will cut out the lines and fittings and use injection clamps on most of the fittings. Yeah, I know...but I have done it before with success. I was also lucky that I have a spare res. But I will need a new regulator (or whatever that small can is) and some new fittings. Oh well, it's 18 years old and still run like a top. It seems like a good decision now to but that old 16V Jetta a few years back! I'll let you all know how it went.

nasty messy job!!! be safe working with the gas!!! watch sparks, your eyes and your clothes.

Are the fuel injection systems the same on both vehicles? Digifant II fuel pump and housing might be different than the 16V stuff.

Housings aren't that expensive IIRC and sometimes they crack at the screw holes that secure the pump to the housing. So I prefer new! :-) Worm clamps work well. ;-)

Hey vwdoc1!

The parts car I bought is the twin to mine. Both are 89 16V's with

Rick

Happy New Year! Turns out it is worse than expected. The fuel reservoir came apart at its seem. And was leaking gas the whole time. I'm lucky I noticed it, and it failed, in the driveway. So I dropped the old res and removed the lines. The fittings and metal parts have been reduced to dust. I will cut out the lines and fittings and use injection clamps on most of the fittings. Yeah, I know...but I have done it before with success. I was also lucky that I have a spare res. But I will need a new regulator (or whatever that small can is) and some new fittings. Oh well, it's 18 years old and still run like a top. It seems like a good decision now to but that old 16V Jetta a few years back! I'll let you all know how it went.

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Good you found a gas leak. But, does not match the symptoms you stated as the culprit. Dave

Sounds like you did good buying that spare twin. ;-)

Like Dave (Dioclese) said, this housing may not be the original problem!

let us know what happens!

Well damnit!

It turns out the problem was the fuel pressure accumulator. I ended up having to get one in Detriot on a Saturday morning. Then I had to wait till Wednesday to pick up the two fuel lines I ordered from VW.

Here's where I start getting angry...I put it all back together and after it pressurizes, it starts. I check for leaks and find a couple on the new lines I bought. Leaking at the unions on the accumulator. No big deal I thought...

I had to pull the lines off the in-tank pump to allow the main to drop. I open the access cover and pull out the pump. It was easier than just removing the lines (not much clearance). I pull everything out from down under and put some teflon tape on the threads. Not too much. It's getting late and I'm frozen so I call it quits for the night. (never did tow it to the shop) Next mornong I realize how stupid I was...I forgot to close the trunk and it snowed all night.

I think it's frozen in the lines now. How do I thaw this thing out in minus 20 temps? Will gas line antifreeze work its way through the pump? Also, is there a way to check to see if fuel is reaching the distributor?

Personally I'd pull all the lines (and everything else exposed to snow) , take them inside where it is warm, let them melt, dry them inside (start with compressed air, then pour a bit of dry-gas in each one, the (carefully, fire hazard) blow them out again.

Did I mention minus 20 temps. I think I'll let it sit till August before I try that again.

Aw, what's a little cool weather mean?