The pumps don't usually suddenly fail. But what can happen is they may get jammed with a piece of grit. They are still in good working order - if you can dislodge the grit. I have had this more than once between my SC and 930. Especially if they have been sitting for some time.
You can have success freeing them if they are jammed, by reversing the power feed and flicking the power on/off. Then run it backwards if it frees. With fuel going thru to flush it. You need to remove the pump to do this. I have managed to free them this way probably 2/3 of the time . You have to be careful not to over stress them while they try to start and can't run. They get hot. And you can snap the drive piece connecting the motor and the pump. In which case nothing lost - it wasn't running anyway.
Alan

To
The rear is new, purchased a few years ago. It is the 044. The front is (I assume), the original one from 78. Dropping the front pump and replacing it.

I will try test for the pressure difference.

Thanks Alan. Update to come

Well, looking at this pic below, it is definitely the front pump. I didn’t know these were packed with oil. Blew out of the pump. At least I don’t have to check pressure now.


http://forums.pelicanparts.com/uploa...1647199186.jpg

They aren't packed with oil.
You are getting close to the problem. They are immersed in fuel. Not sure what you have there. That may be some evaporative fuel residue.
But you can remove the pump and hook 12v across the terminal as see if it functions.
Alan

there is a fuel flow test you do to determine if the pumps are good.
also do the flow to the WUR

make sure you have gas in the tank.
make sure both have power.
when one pump stops running the other one makes noise, at least when i tested it.
also, try running one pump at a time.

no gas will act the same way.
dont ask how i know........it was my brother

Removed front pump and hooked it up to a battery just to test if it is even active. Nope - dead.

Talking with Alan a bit...... He confirmed what I thought is another freakin problem. I have a blockage. Removed the main line to the fuel pump - ready to cap the outlet and the fuel basically had a fast dribble. So I am sure it took out the pump.

Explains when testing system pressure, hit a high of only 3.75 bar. Then started the pressure wouldn't hold - it was being reduced by the blockage and problem the front pump dying.

Flushing the tank next. New pump on order. My front pump was a 044 - don't remember installing that particular one (haha). It was a while ago.

Any recommendations on cleaning out the blockage. I have not idea what it could be since I had the tank "professionally" cleaned. Then I had it powder coated. The only thing I can think of is when it was cleaned for powder coating that the company I had do it, did not completed block the openings and their blasting media got in.

Thanks again guys. Hopefully I am getting closer

http://forums.pelicanparts.com/uploa...1647313635.jpg
These are the tools I made up to flush my tank. Yes - blasting media will screw your pump. probably what happened when you were doing your tests, the pump locked up on the grit. Then overheated and burnt the motor. It needs fuel flowing over it for cooling. They get hot pretty quick without it (less than a minute).
I had to order the blanking plug from a tool supplier - but readily available. I tapped in a hose nozzle to direct the fuel flow to a container. I actually machined a slight downslope contour on the inside of the plug to direct flow to the nozzle fitting. Flushed the pump line backwards (into tank) using an 044 pump. That could drain straight out the plug fitting. Then pulled the drain plug and could just get enough access with fingers to clean any residual grit in swirl pot. Repeat as necessary. If you have grit in the tank on the outside of the swirl pot, you may need to remove the tank and sluice stuff around and tip out via the sender hole.
I ground down a bolt head and welded a nut thing on for my drain plug tool. It will be tight. There is an O ring seal just inside on the neck of the plug. I think the reason I ground the bolt head down was to start with a bigger bolt - so it didn't snap. There should be a metric bolt head size that would fit - but the shank may be a bit light. Worth a shot first. There is a proper tool of course - but who needs those? :-)
Good luck
Alan

Did you try the terminals for continuity? the pump may just be jammed?
If no continuity, then burnt out. Binned. If continuity, jammed and maybe able to free. I have freed a few.
Tap gently on concrete floor a few times. Hook to 12V with reverse polarity. Only power it for a second - just that initial kick. If it does not fire, disconnect. Repeat, repeat etc. It will heat up, even if jammed. let cool, try again. If you get it to move, flush backwards with fuel and you have a good working pump again.
Alan

haven't tried the continuity test. Thanks Alan, I will give that a shot tonite.

Ordered a new pump from Chris at turboKraft. 044 are now discontinued - being replaced with a #200. Chris informed me that the are smaller diameter, draw less amps, and have higher pressure. The bad is that they will not fit in 964s or 993s. Chris was not happy. so they have to go back to original stock pumps on those cars.

Tank is cleaned and flowing. Wasn't too bad. Return line wall clear, didn't have enough fuel into for the gas to back flow out.

3 day shipping from Chris. So that I can reassemble this weekend and back to pressure testing.

Should be alot easier to work with now!

Hello all, back at this again. Out of town a few days, and also had to the new pump and fittings. The Bosch 044 is no longer available, being replaced with #200. Minor issues to deal with, the pump is smaller in diameter and longer in length. The fitting sizes are also different. However it has a higher output and draws less amps (sounds okay so far). The pump came with adapters for the input, however the output is smaller for whatever reason. If used braided SS lines with AN fittings. I had to order new fittings for the output.

Installed everything. Double checking hose and electrical connections. Fueled up the gas tank to a little over half. Turned the ignition on and both pumps fired up.

First pressure test I did was to check the fuel pumps after the the fuel filter. Connected the pressure gauge and turned on the pumps. Pressure came up very quickly, ran past 7 bar and kept going. If you would extend the gauge markings, it appears it hit 9 bar.

Hooked up the test equipment to check control pressure and system pressure after the fuel head. Control pressure went up fast and went beyond 5 bar. Quickly check system pressure, back up to 9. Also the fuel head was “squealing”. The pressure plate was firmly pushed upwards and very firm. I just tried to see if it would move, it was extremely firm. Then just shut it down.

Really, now what?! Do I buy and install a pressure gauge with a valve to reduce the pressure to the head? Or other?

Thoughts? Thanks

I also ran the tests with the electrical green connector at the rear of the fuel head, disconnected.

I will take a look at the shims in the fuel head. I will start with removing some shims and go from there

Something very weird going on here. I just hope you are testing these pressures correctly. You don't usually test pumps after fuel filter - tells you nothing other than what the pump spec is for pressure. What you need are WUR pressures and System pressure. If you really do have a system pressure of 9 bar, you won't have enough shims in the FD to reduce it - my guess. Probably only 2-3 shims and about 0.5 bar to loose. But worth a look first. Take all the shims out and see what you get.
Alan

Have you looked at your system pressure regulator in the fuel head? There should be a spring a valve and some shims. The shims regulate system pressure. I had one that someone had removed the valve and stretched the spring to compensate which resulted in weird readings which is why I looked.

http://forums.pelicanparts.com/uploa...1649069142.jpg

I did the "fuel pump" test after the filter because I wanted to see the raw fuel pressure before the fuel head. I hooked up the WUR/fuel head for the normal system and control pressure tests. The WUR pressure was really high 4-5 bar. The system pressure buried the gauge.

Yes, I double checked my gauge hook-up. Closing valve on the WUR side.
Again, the fuel head was literally screaming - I am assuming way to much pressure. I didn't want to run this very long - internal damage to the fuel head (?). Tonite I am looking at the shims. I just hope there are some shims being used. If not - another step to deal with.

i go back to your post 14.
control pressure higher than system P.

when i get something like that i look at what am "I" doing wrong.


when doing the pressures test, the return from the WUR goes through the pres reg.
could be stuck PR, could be the opening is too small to let enough fuel through if the pump is putting out more fuel.

do the fuel system test.
fuel flow out of the fuel head and WUR fuel flow.

Yes - as above - verify.
I am beginning to wonder if the return line is crimped/blocked. Like nowhere for the fuel to go after reaching the FD.
Can you blow thru the retune line - by mouth - 1-2 psi. Bubbles in fuel tank.
Alan

Post 14 reflected testing the system with a bad front fuel pump. Those numbers are irrelevant. New pump is working great and the pump pressure is a bit high, but a good start.

When I cleaned the gas tank, the return line was disconnected and I ran air thru it from the engine bay to the tank. No blockage.

Removing the FH shims tonite. Then test it

Disconnected return line and blowing air thru - not good enough. You need it connected to the return in the tank. Something weird here. Then see if you can blow thru by mouth.
Remember - your feeder line to the pump was seriously blocked - in the tank. Wrecked the pump. Whats to say the return line is not blocked with same stuff?
Alan

thanks for the diagram bucket list. However that is not the fuel head that I have. I will take pics and post.

I bought this fuel head from Dave at TurboKraft when Chris Carroll worked for them. I was intended for a V-8 Mercedes race engine. Dave revised it to a 6 cylinder to use on Porsches. About 3 years ago I send all of my CIS components to Chris at TurboKraft for a complete rebuild. This fuel head is supposed to push alot more fuel than the factory ones. Not sure what that means for the WUR though. I probably should contact Chris.

My "pressure control" is mounted vertically at the front of the FH. I removed the banjo cap and the plunger. No shims, also no springs. Since it is mounted vertically, the plunger moves upward under pressure. The shims limit the height that the plunger will move. So the only way to increase the plunger height position is to increase the height of the banjo fitting.

No shims - so I fitted a thicker copper crush washer at the banjo insert. I increased the thickness by .5mm. The system pressure did drop. However the gauge still reads beyond the 7 bar markings. But it did drop.

Question - Do I calculate how thick this washer needs to be to bring the system down to 6.5-6.7bars? Do you think that I can stack crush washers without a leak? Quick estimated guess is that I need a the crush washer to be about .125" (5mm)

The way you are describing your CIS/control pressure system is like something from outer space. I just cannot relate to it. Adding shims normally makes the system pressure higher.
You have a one-off totally different system according to your description - so you need to post pics so we can understand what you have.
Alan