I've got an original 6 with the factory fuel pump. . after sitting for 6 months, the pump runs but has low fuel pressure on the carb side. . Has great pressure on the tank return side. .no line obstructions. . . tested out of the car. . . won't lift fuel over level in the tank. . . anyone ever tried to adjust or repair one



Read down. . . Fixed !!!

Has fuel tank screen been replaced recently? May have picked up something.

another issue I found, no screen in the tank, looks like someone ripped it out from the top so only bits left under the outlet nipple. . then there were no fuel filters anywhere. .
My next step was to pull the top of the pump off and see what the pressure adjustment looks like. . . just wondered if someone else had been successful in a similar task.

I was able to find the o-rings in fuel-safe Viton, and have been able to get into the pumps to replace them. But there are two MAJOR issues with resealing a pump.

1. The outer housing is crimped onto the motor. These crimps are very difficult to pry apart and even harder to reinstall. If I were to even have a hope of making a reseal job work, I would expect to make special tooling to release and make those crimps.

2. The small silver 'button' on the side is the internal pressure relief. That cover is also crimped on, so there is a similar issue to #1, but also there is a seal inside that I haven't located (or tried).

The best bet is to call Fuel Injection Corp (925-371-6551). They rebuild the 914-4 pumps, including machining a new pressure relief cap (button) from solid aluminum. They should be able to rebuild your pump.

Keep us posted. I have two 914-6 pumps that need rebuilding.

Collapsed/missing screen parts makes me wonder if they made it to the pump?

Got a couple myself.
Anyone using one of the new Pierburg carb fuel pumps ?

I've had great results with the Pierburg pumps. They easily fit up front by the steering rack, so you solve a possible vapor lock issue as well by getting it away from the engine's heat.

The funny thing about that thread on the bird is no one really admits that they have tried the pierburg pump. George is the only peep here that states he has used them.

Plus the only review on pelican is "I got it and ohhhh it is shiny and pretty ...can't wait to try it"
And it is a 5 star review no less...




WTF kind of totally fucking useless review is that

The Six conversion section was written a rather long time ago. I don't know when they would find the time to re-do it; I certainly don't have enough time for it. I believe that Tom was one of the main people to provide info for the section, and he is no longer with Pelican.


Anyway, on with the pump: I have been able to take apart the top section, clean the rotor and pucks, and re-assemble. The pump did not leak after I did that; I may have been lucky. I did not touch the crimped parts.

The pucks are small, and easy to lose. Don't let them get away. The top has two layers, the housing layer and the cover. The housing is sandwiched between the cover and the main body of the pump. Both of them need to be in the correct orientation with the rest of the pump, or you get no pumping or the pump goes backwards! (Don't ask how I know that.) So mark the pieces before disassembling.

--DD

So the answer is, YES, they can easily be taken apart and the pump portion serviced. .
In my case, the motor ran fine, i just did not have sufficient pressure to lift the fuel to the level of the carbs. . meaning it was putting out less then 1 psi. In my mind I was looking for some sort of blockage. . Last picture is of the pump head apart. .

WARNING- As Dave D said, mark the pump, intermediate plate and head outlet before disassembling. . the intermediate goes back correctly in just one orientation, although you can put it back in 8 different variations.. The center hole that goes around the rollers is offset and must be in the proper place to coincide with the 3 outlet ports. . otherwise in could be out and suction could be pressure. .

Beside the center lobe and 5 rollers, there is a small crimped cover with a small o-ring inside and over the plunger port. I reused the o-ring and re-crimped the cover tightly. . .
Apparently the strength of the small spring regulates the outlet flow. . . the plunger is pushed toward the inward passage by the small spring. The plunger head then covers the inside port to the outlet tube. . the spring regulates the outlet flow. This plunger slides back and forth in the top cover, regulating gas flow either to the carbs, or back to the return port to the tank.

In my case the plunger was gummed up with varnish and debris, and helf in a mostly closed position. . j. . It was really tight and had no movement but some PB Blaster and a few dental tools took care of that . Once it was all the way out, a little cleaning and it was easily sliding in the bore of the passage.

First picture is the test arrangement i made, mostly to ensure no leaks and sufficient pressure. . On the initial test, the pump would not lift the fuel more that an inch above the pump level. . Now has plenty of pressure now, raised fuel 3 feet in elevation to the suspended can and I can stop it with my finger tightly held over the outlet port. . I plan on running an outlet pressure regulator and gauge to insure no pressure in excess of 4 pounds. .

So for posterity, they can be taken apart, cleaned and reassembled. . just be careful about exactly how it comes apart. I am still puzzled as to what actually controls the outlet pressure as the bypass plunger seems to be more related to flow rather than pressure. Maybe the strength of the little spring , but at this point , it works and that's good enough for now. . pressure could be a relationship of the motor speed and the roller dimensions. .

I had an old 914-4 pump laying around and took it apart. It was locked up from gum and varnish. I cleaned it up and it runs and pumps. Seems not to leak either.

I did not take the crimp cap off though.

Nice write up !

Show more pictures of the new found Six !

As for no filter this reminds me. The Porsche 914-6 PET catalog shows no refrence for a fuel filter which seems odd. I have seen the filter location on several cars in various places. I was wondering where it was located from the factory?

I think it should be in front of the fuel pump and thats the way I run mine.

I have also seen them in the engine compartment which would be behind the fuel pump.

Just curious where the factory put them?

Factory ?
Not original on a 6, AFAIK only the screen in the tank.
Anyone know otherwise ?
Attached is pic of my added filter.
Oh, another thing. Before disassembling a 3 port Bosch pump scribe a line across the edge of the three sandwich pieces to aide orientation on reassembly.
Where can the Viton O rings be sourced ?

the o-ring in the crimp cap appeared to the a square ring, not round. .
Viton rings available on McMaster / Carr. .

If you don't take the crimp cap off, you can't remove the plunger and spring assembly . . Needs to come off if plunger or piston is sticking. .