Pierburg Fuel Pump Rebuild Problems

[Samer1275]

I bought a non-rebuildable alternator style pump with a shorter rod and it has been working just fine since I bought my 69 Ghia about two years ago. It still works fine.

However, partly to make it slightly more correct and partly to improve hot restarts, I wanted to install an OEM pump. I got a Pierburg from the Samba and attempted to rebuild it.

Here's my concern: It DOES make a sound when I pump it with my thumb but I don't feel suction or pressure on either inlet or outlet. I took the working one out of the engine and it does create suction and pressure when I cover either inlet or outlet with a finger and pump with my thumb. Keep in mind that the lever is further out on the alternator style pump so it is potentially easier to pump by thumb.

My biggest concern is this: when I did the rebuild, the circular check valve seemed to work fine. I left it alone. The valve next to a piece of metal and screw seems unclear to me. If I screw it in tight, then the valve tilts and stays open. if I loosen the screw a little, the valve will close or open just by gravity if I tilt that part of the pump one way or another. That's how I left it. How is that valve supposed to be working?
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1969 Karmann Ghia Coupe

[kreemoweet]

If it's like the Pierburg pumps I have, the inlet (suction) valve consists of a thin piece of stainless
steel, which sits flat on the pump body, covering the inlet hole; then there's a retainer piece with a
somewhat curved arm; and a screw to fasten them both to the pump body. The screw should be snug,
and nothing should move around loose. The flat flap over the hole should stay flat when the screw is
tightened. The flap is flexible, and will bend away from the hole to admit fuel when the moving diaphragm creates suction in the pump chamber. The retainer prevents the flap from opening too far.

Which rebuild kit do you have? The newer ones I have seen are full of bogus parts.

Did you preload the pump lever by 14 mm as described in this thread: http://www.thesamba.com/vw/forum/viewtopic.php?t=1...ding+jig.?
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'68 bug: seized by the authorities
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[Samer1275]

Thanks for the reply. I think that valve is the problem. Hopefully the only problem.

I guess I need to bend something so that tightening the screw keeps the valve closed.

To answer your questions; I preloaded by hand as was necessary to get the holes in the diaphragm to line up with the pump. I reused pretty much everything minus the diaphragms. The kit was Wolfsburg West.
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1969 Karmann Ghia Coupe

[Samer1275]

Update: I took the pump out and I opened it up. I unscrewed the suction valve assembly and I put a bend in the steel valve such that it would stay closed when I tightened the screw snug. It looked OK but I have no way of testing it short of putting it in the engine, I suppose.

After putting it back together, I'm still not sure if it is working. I put it back in the engine and hand cranked it a few times with no fuel coming out. I know it takes two engine cranks for one pin cycle, so I suppose it is too much effort to test it that way. I just don't want to wear out my starter and battery only to find out the pump still doesn't work.

How many engine cranks does it take to get fuel pouring out of a completely dry pump?

If this pump is hopeless, I might just have to put the working one on and count how many cranks before I see some fuel in the out line.
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1969 Karmann Ghia Coupe

[kreemoweet]

I recently tried installing a rebuild kit I got from Wolfsburg West in a Pierburg square-top fuel pump. I found
that most of the parts in the kit were bogus: did not fit, and did not work. The main diaphragm pull rod was
too short, making it impossible to install with the correct 14 mm preload. The reason for the preload is to
ensure that the diaphragm is not stretched (the diaphragm is supposed to flex, not stretch) when the operating rod in the engine reaches in maximum height of about 13 mm above the plastic pump stand.

Another bad thing about a short pull rod, is that it will cause the
diaphragm spring to be compressed too much, resulting in excessive pump output pressure. The cutoff valve
diaphragm from the kit was made wrong, and did not work. The delivery (output) valve parts also did not fit.
There were other problems with the kit. I hope you have better luck with yours.

There's a great deal of trapped air in an empty fuel pump and it takes a while for it to begin pumping normally.
You can test the pump by hooking up some clear vinyl tubing to the in/out fittings. Find a funnel with the right
sized outlet and attach the inlet tubing to it. Fill with gas or other suitable fluid. Start pumping away on the
lever. Pretty soon you should have "gas" coming out the outlet tube. You can tell if the delivery checkvalve
isn't working, because the air bubbles will mostly just go back and forth. For a thorough test, you should get
a low-pressure gauge (0-10 psi would be ideal) and attach to the output tubing.

Here's a post from someone who tried to install one of those WW kits last spring: http://www.thesamba.com/vw/forum/viewtopic.php?t=590247&start=0.
_________________
'67 bug: seized by the authorities
'68 bug: seized by the authorities
'71 kombi: not yet seized by the authorities

Stop dead photo links! Post your photos to The Samba Gallery!

[Samer1275]

Thanks for all that info. My thumb is getting really sore from all the pushing on the fuel pump rocker.

At this point any pumping action will be a big positive. As I stated, I did retain as much as possible from what was in the pump when I got it. So all the springs are the original springs that were there and not the ones from the kit. This includes the spring attached to the main diaphragm. I used the split retainer from the original to attach the old spring on the new diaphragm.

What I'm thinking of doing is either cranking the engine by hand or by starter a bunch of times and then taking the fuel pump out once again and opening it up to see if any fuel got into it and to see what shape that check valve is in.

I may have to build one of those jigs as my thumb is too sore to replace that diaphragm on the pump one more time.
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1969 Karmann Ghia Coupe

[Samer1275]

Long delay as I waited for a new flange. Yep, I broke the flange. I got frustrated as it wasn't pumping so I put the was-working pump back on but it didn't go on smoothly. Dumb of me to keep going. I hand cranked it a few times and the flange broke.

Fast forward to today. I managed to get the broken flange out and the rod out without much trouble. I had to use the small pliers from my swiss army knife to get to bottom piece out. I reconstructed the flange to make sure I got all the pieces out. No worries

Another thing I bought was carb cleaner. I sprayed a bunch of it into the Pierburg pump and there was definitely something stuck at the inlet preventing it from pumping. Now I can hear it pumping and I feel pressure at the outlet when I pump with my thumb.

Here's my new concern: If I fill up the inlet with carb cleaner very slowly, as it overfills I see the interface between the brass pipe and the pump body soak up with carb cleaner. So I'm now concerned about this. Is this normal? If not, what can I do about it. Both pipes feel very solid on the pump body.

Thanks again for your assistance.
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1969 Karmann Ghia Coupe

[WD-40]

[Samer1275]

Thanks for the good tip. I still want to use the Pierburg pump. Now I'm worried about the fitting at the inlet. I want to make sure it is safe. Like I said, the pipe feels very solid. Any advice?
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1969 Karmann Ghia Coupe

[lemke]

Here is some info from the Ghia forum - a lot of people do not realize that you can use the stock later fuel pump with an alternator:

http://www.thesamba.com/vw/forum/viewtopic.php?p=6097743#6097743

And not all rebuild kits are made alike - some have more/better parts - I would reccomend reusing some parts from your OG pump.

Here is a link from Hot VW's that details rebuilding fuel pumps:

http://www.hotvws.com/content.php?contentID=45

EDIT:

As you can see from the picture, Airhead parts offers a fuel pump rebuild kit that has more parts:

Airhead:

Wolfsburg West:

[Samer1275]

Thanks for the info. I figured out a way to test my Pierburg pump and it works!

I don't have a syringe and I don't have a funnel small enough to fill the inlet with fuel. So I took the top of the old rebuildable non OEM pump, flipped it upside down and hooked up its outlet to the inlet of the Pierburg. Well, just as I had hoped, as I pumped with my thumb, the suction opened up the one way valve on the half pump and fuel got sucked in. I repeated a few times until fuel came out of the Pierburg outlet. And no leaks. I'll give it a day for all the spilled fuel to evaporate and try to get it installed and running tomorrow. Looking forward to see if I get any hot restart improvement with this pump!
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1969 Karmann Ghia Coupe

[Samer1275]

Still more problems.

I tried to start the car today with a the primed Pierburg fuel pump. It starts and if I keep it revved it seems ok but it idles like crap. Very intermittent, low RPM and generator light flickering. If I rev it for a few seconds, it will idle OK for a few seconds afterwards, then back to the crappy running. Black smoke comes out of the exhaust also.

Now I'm really puzzled and frustrated. Any suggestions?
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1969 Karmann Ghia Coupe

[Samer1275]

Success:

I added two additional gaskets between the flange and the fuel pump to make it a total of three gaskets. This reduces the relative motion of the rod on the fuel pump rocker which reduces the pressure of the fuel going into the carb. Black smoke indicated that the car was running too rich.

I started it up after a couple of tries and it idled smooth with no black smoke.

Thanks for everyone's help
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1969 Karmann Ghia Coupe

[kreemoweet]

[scrivyscriv]

This is what Wolfsburg West currently advertises as of 11/16/2014:

Which is totally different than what is pictured on the above comments.
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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[kreemoweet]

[scrivyscriv]

[ROCKOROD71]

Wherever you buy a rebuild kit from, call them up and ask what brand of kit they are selling you. This is one that I got some time ago, can't remember from where, but it is a good kit, made in Brazil, and it contains all the parts to rebuild a Pierburg style pump (mine is the version with the six screw top, not one screw). It even has a new removable filter.

The brand seems to be "TR" made in Brazil. My pump has been running about a month now with no issues, although you can see the pin wiggling, it uses two e clips to hold in in place, been secure so far.
The part number is there on the bottom of the box. It was about $30 IIRC
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1971 STD BEETLE- DD-1st car, 1st love. keepin' it stock! 1600DP, Solex 34-3 Mexi Bosch SVDA Dist NOW w/POINTS
1977 WESTY "KrustyKamper" 2L FI

[scrivyscriv]

I ordered Wolfsburg West's rebuild kit anyway, and here's what happened to it:

Bottom shows the original pump diaphragm assy, top shows the seperated WW diaphragm after being operated on my engine for a few minutes. It dumped gas all over and into the engine, so I tossed the pump to the side and ran my "crappy aftermarket" pump. I finally got around to opening up the pump three months later to see what exactly happened... Before I ordered, the WW rep and I went back and forth on a few emails regarding quality and warranty; he says WW stands behind the products they sell. We'll see.
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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[kreemoweet]