A bit of background. TurboKraft rebuilt the FH and the WUR for max fuel flowing modified my intake manifold (ported and polished). This was only a few years ago. The engine was built by Henry at Supertec. He added a few internal goodies to boost HP and reduce turbo lag. Chris at TurboKraft shipped new billet aluminum intake bodies ported to match the intake manifold and has individual injectors for water/methanol.

The diagram shown in post 33 is close to mine - but I have additional access plugs and bolts. The main feed needle valve is off to the side as shown (my bad - I rushed my post). However I have a threaded hex head plug at the center of the main retaining bolt. This plug controls the outer travel limits of the valve spring. If you remove this plug the valve spring could be removed.

I do not have any shims in the main valve spring body/housing. So I am at the max on reducing pressure. However I did install/stack additional copper washers at the hex head plug to increase the travel limits of the valve spring. This resulted in reduced fuel head pressure, however my readings are still beyond the gauge markings. I would estimate it is at 8bar.

I do have the valve of the testing gauge on the WUR side. I went thru everything again. Made sure that the filter in the WUR was clear, check fittings, etc. My readings at system and control pressure are the same.

I am not sure how I can reduce pressure to the WUR. The vertical valve at the top of the FH has no springs or adjustments of any kind. I can substitute a thicker copper washer to gain a bit of travel, but that is it.

Haven't tried starting the motor again. I may do this tonite.

Do I need to check the return pressure from the WUR to the fuel head? I do not see how the WUR receives lower fuel pressure in this situation - let alone pushing more pressure when the WUR gets to temp. I appears to me it is all in the return line - after the WUR.

Suggestions?

PICS:
http://forums.pelicanparts.com/uploa...1649257229.jpg
http://forums.pelicanparts.com/uploa...1649258071.jpg
http://forums.pelicanparts.com/uploa...1649256685.jpg

Fuel head numbers
http://forums.pelicanparts.com/uploa...1649256685.jpg
http://forums.pelicanparts.com/uploa...1649256685.jpg

Tested fuel pressure out on the WUR. Why? So that I can get some understanding how parts operate in this system. I also measure fuel pressure after the filter so I had a base line for comparison.

Final pressure tests of both input and return lines at the WUR…..the same. Same as the main fuel pressure off of the pumps…..around 8.75 bar. Well, at least I have pressure.

1). Reduce pressure to the FH or in the FH
There are no shims in the main valve needle fuel feed. I added additional copper washers to the main fuel feed retaining bolt. A little reduction, but not a lot.

Do I install a valve between the fuel filter and the FH to adjust the pressure down?

Going to attempt to start up the motor tonite and closely monitor.

that is not an adjustment on top of the FD.
the limitation on the sys PR is the small openings in the pistons inside.
blocked return is only thing that will give you fuel PUMP pressure after the FD.
even if the sys PR was working to its full capability you would have SOME sort of drop in pressure but it sounds like have the same pressure before the FD as after.
blow through the return like, you should hear bubbles in the tank

do the fuel FLOW test.

i have two sets of those gauges.
one set reads much higher than the other above about 4 bar. both were new at the same time.

I did the return test when I flushed out the fuel tank. No issues

Why not just test run the return to a canister as it would resolve the return restriction = high pressure

Not a bad idea. Doing that tonite

Btw, tried starting the motor……ZIP

It is still unclear, to me, if you have tested the return to the tank - in the tank. The feed line to the pump was blocked. Have you confirmed the return line in the tank is not blocked? With 8 bar behind it you would think it is clear - but you need to be 100% certain the return in to the tank is not blocked - not just the return to the end of the fuel line.
Alan

I am very suspicious of your system pressure adjustment process. I have never heard of such a process, and I can't understand why a deviation from the norm would be required. By shimming the whole valve body out from the FD you are effectively disabling the way the system pressure is controlled. Basically opening the FD up to pump pressure, and not allowing the spring loaded needle valve to do its job.
Alan

Let me tell you a story about a similar problem I ran into several years ago. I bought this Turbo Porsche. It seemed to run really well (fast) but was also very rich. I knew my way around cars but had never worked on one of these. My first attempt at checking control pressures made me and everyone on here think I was doing it wrong. My first test showed 5.3 bar cold and warm, everyone said I was doing something wrong because it wouldn't run like that. I took my wur apart and cleaned it finding the input screen clogged. I cleaned my injectors and ran all sorts of fuel flow tests. My Idle mixture screw was turned all the way in and seized, took a few days of soaking to free it up. I still had problems so I pulled the System pressure regulator from the fuel head and found the valve missing. (sent you a pic in an earlier post). I replaced it but couldn't find a spring so I had to resize the one I had. After this my pressures came into line and I made progress. I had the wur rebuilt and modified, added air fuel monitors and permanent control pressure gauges and she has run pretty well for the last few years. Many thanks to all of these guys with endless suggestions to help me figure this out.
Good Luck!

i agree with alan, #49.
yes, clogged input screen is common.

you really need to do the fuel flow test.
you remove the return from the FD and measure the amount of fuel OUT of the FD. i think its for 30sec.
then do the same for the line to the WUR. that one i think is a min.

a clogged sys PR

like i said. if your sys PR is working at all and your return is clear then your pressure should be some what less than it is before the FD.

if you connect your gauges to the port on the FD for the CSV you can check sys pres there too.

There is no clog. Return lines were full of fuel - that was fun! The return lines are clear. I also let the pumps run with the return line disconnected - free flow - no reduction. Also measured the pressure of the return line - a bit less then the input side. Maybe 1/2 a bar - but still reading off the scale - past 7bar.

All fuel lines are new. I ran 1/2" OD aluminum lines thru the tunnel (I will never attempt that again - took me 5 nights of incredible patience). All fuel lines are stainless steel braided alcohol resistant lines with 8AN fittings.

I can do the flow tests - I already know it will be more than stock. The amount of fuel coming out of the main input is quite a bit.

Do you think I will have to install a valve, pre-FH, to reduce the pressure?

Dumb question - what controls the reduce fuel pressure at the WUR? The WUR restricting flow or FH internals.

thanks all

Hello Turbo friends, It's been a while. I hope everyone is good. I see a lot of new people here. From my past experience adding a 044 pump to the rear is not a good thing and will cause the fuel press to be too high and run lean. You can use one 044 pump up front a loan and get good pressure and be good for 400 RWH. I prefer leaving the rear pump stock as well the front, that you can set everything to stock spec and you have room to adjust, including the system pressure valve shims at the FD

I have two 044 s on mine , and the system pressure is maintained as per normal adjustments.
There are/have been several CIS similar threads going lately and I loose track of which is what. But have you checked that the screen on the WUR is clean? Underneath the union that joins to the FD.

"Dumb question - what controls the reduce fuel pressure at the WUR? The WUR restricting flow or FH internals." - The bimetallic finger/spring pressure on the internal diaphragm in the WUR controls the variable pressures - Cold Press, Warm Press, Boost dump press. The system pressure is controlled by the spring loaded needle valve in the top of the FD - except yours, apparently.
Have you pulled it out and checked it has a spring? As per post #50.
Alan

[QUOTE=Alan L;11659585]I have two 044 s on mine, and the system pressure is maintained as per normal adjustments.

Hi Alan, You're right it can be done and your car modified. But on a stock 930 with stock CIS, 044 pumps may through things off enough to have issues.

It seems our friend is running on one pump from what I read. That can't help

As in the diagram on post 33, the main pressure needle valve has a spring. Except mine has a threaded hex head plug in the center of the retaining bolt. I have already posted this. I can remove the needle valve by removing this plug and leaving the retaining bolt in place.

I have a banjo bolt at the top of the FH as shown and labeled in my pics. The plunger can be removed using a magnet. No spring. Apparently it moves with the fuel flow, the pressure pushes it vertically. There is a port in the FH that runs 90 degrees to the rear, in relation to the plunger. Removing the rear banjo connector (that runs to the main input of the WUR), and placing a mirror to view inside the port, I can see the vertical plunger.

Again this FH and the WUR were rebuilt and modified by turbokraft.

Do you think I will have to install a valve, pre-FH, to reduce the pressure?

Dumb question - what controls the reduced fuel pressure at the WUR? The WUR restricting flow or FH internals.

thanks all[/QUOTE]

Someone posted a diagram of the FH with valve, you need to remove the valve and remove shims to reduce the system pressure and shims to increase pressure. If your pressure is high then there's a reason for that. The 044 pumps increase system pressure.

Reduce the system pressure and the fuel pressure will also be reduced at the WUR,

I did have this engine running about 2 months ago, but only at idle. It stumbled when I tried to accelerate it. Started it again the next day, but had to in rich the co mixture adjustment. Again no acceleration. Stumbled and stopped.

Could not get it started again. This is when I realized the front fuel pump was dying. Bought the pressure testing equipment and here we are.

A question was brought up about changing the outside copper washers to a thicker washer to further reduce the system pressure.

This is a very good overall video on CIS adjustments. However it is on a earlier non-turbo motor but the basics are all there

Jump to 21:00 and he discusses reducing pressure when the shims are not present to remove
https://www.klassikats.com/2021/08/21/how-to-fix-your-porsche-c-i-s-fuel-injection-system/

The valve on the 930's are different looking, there's a shaft/pin and behind the spring there are shims, I would buy a new valve from our host, it comes with many size shims as well. Can you share your numbers? Cold, warm and system pressures Please