Fabio421

What about the pictures I sent you? I pointed directly at the ports you need to hook up to.

Tampa 928s

I could not open them up big enough to see what they were; looked like you were giving me the finger , it's the age thing you know!
From what I could see on your pictures you showed both the FD and Wur and what I am told now the gauge needs to be hooked up to the WUR inlet and outlet and not to the fuel distributor directly; am I wrong?

jpitman2

DId I not explain it clearly enough? re-read my recent answer please. If you connect directly to fuel distributor you can bypass the WUR , and never see its control pressure. You need to splice the gauge into the pipe from fuel distributor to the INLET of the WUR, which is the pipe you have your finger on in your first pic - lhs of WUR looking in to engine bay.
jp 83 Euro S AT 53k

Tampa 928s

I got it; just giving Shawn a hard time, it's his gauges and he sent me pixx on my cell phone, not sure if he hooked it up different then what you suggested but pictures were so small I could have been looking at a lug nut!
Seems like what you are describing with the connection this way you can measure Fuel Pump max pressure with it closed, fuel pressure with it open and drop off pressure when closed and motor off, seems to make sense.

Tampa 928s

Hooked up tested as shown I measure fuel pressure and control "pressure which is not accurate due to motor not running. When I closed the valve pressure drops fast after 1 or so minutes to less then 10 pounds.

I wanted to check a hot start issue and it seems if gauges are hooked up correctly it is leaking back to the tank by either the accumulator or one way valve, feedback!

Luis_M

Comments:

Picture 3 (valve closed) shows System pressure approx 5.1 bar looks ok, means fuel pump probably ok (at least with engine off).

Picture 2 (valve open) shows Control pressure approx 4.9 bar---way too high. WUR probably needs to be cleaned out. With the electrical heater disconnected as you show in the picture 4, this should be more like 2 bar (depending on temp in your garage). This will definately cause a starting problem, but it should be more of a cold start problem. Before attacking the WUR, though, I'd make sure the problem isn't on the return side. To check this, crack the connector on the outlet side of the WUR (The right sided connector attached to the banjo fitting) while the gauge valve is open and fuel pump running to make sure the CP doesn't drop, then retighten it. If pressure does drop, the problem is between the WUR outlet and the tank on the return side, and cleaning the WUR probably won't help. Small rag needed to catch slow fuel drip during this test.

Picture 5: residual pressure should be higher. should be 2 bar at 10 minutes, 1.6 bar at 30 minutes. Could be either accumulator or fuel pump check valve.

Also, one more place for trouble. Does your car have a hot-start WUR bypass solenoid? My 81 Euro S does. PET p 107-30 part #1 shows it should be there for all Euro 1980+. This solenoid is supposed to bypass the WUR during a warm start-up, connecting the control pressure outlet at the top of the distributor directly to the return line (essentially zero control pressure) during a hot start. Instructions for testing this also in WSM. If it leaks, it can be a third source for drop in residual pressure.

Other possible sources for leaks include the fuel injectors and cold start injector.

Relevant WSM pages are in chapter 25

GOod luck... Once you've got the pressures in line, you'll need to adjust the A/F screw, since it will probably run quite rich

Luis
1981 928S Euro 5sp

Tampa 928s

Some one has replaced the filter and pump so I am not sure where the anti siphon valve is placed it looks like this is it on picture 3 and 4 on the filter located on the right.
From what I was reading it should be under the fender but sure does not seem like anything was there in the past.
The cost is very high for the accumulator any way to test it for sure?

Luis_M

the check valve you are looking for should be screwed onto the outlet of the fuel pump. The banjo bolt screws into the check valve. You need to check the part # on that fuel pump, though. The "blue" pump may be the EFI USA 1980 fuel pump (928.608.104.01) and not the CIS Euro 1980 fuel pump (928.608.102.02). This seems to be a common mistake when these Euro cars get serviced (ask me how I know). The Bosch CIS pump should be black or silver and is rated for higher pressure/flow than the blue EFI pump. THe silver pump has an integrated check valve while the black one does not.

jpitman2

My 83 Euro had an S4 typoe pump on it when I got it, never had an actual issue with either delivery rate or system pressure with that pump, so unless yours is sick, I would look elsewhere. Start by replacing the check valve on the pump outlet - relatively easy, but I suggest you remove the whole pump+filter assembly and do it on the bench - there is a reason the S pipe is carried by many shops as a spare part. If that doesnt help your hot start issue, check the accumulator for weeping at the breather, or fuel under the screw (if fitted). If you have the above mentioned pressure reducing solenoid and temp sensor (near cyls 3-4), more checking - remove the temp sensor, and check it in hot water on your cooker - specs in WSM. On mine it closed at approx correct temps, BUT it never went below ~20 Ohms, which is high enough to prevent the solenoid closing, which gave me hard starting hot. Eventually found an affordable replacement (off a 944), and adapted it into the fitting on the heater water outlet (m10x1->m14x1.5), fixed problem. If you dont have this set up, and problem persists, next possibility would be accumulator. If the hot start issue is caused by rich mixture (flooding), check cold start injector leaking, and/or thermotime switch.
jp 83 Euro S AT 53k

Tampa 928s

Is there any other tests to verify the Fuel delivery with the way it is now connected. What I see some one has added a ground to the sensor and would like to ID all the fuel lines to get a better handle on this Cis system.

Fabio421

WYF am I looking at here?




And where is the other side of this gauge hose hooked up? I don't see it in any of the pics. Normally it would connect to the top center port on the fuel distributor but I noticed that odd item ( shown in pic #1 ) that is mounted between the fuel distributor and the WUR.

jpitman2

Pic 1 post 25 shows the temp sensor for hot start enrichment (lowers control pressure). remove leads, unscrew sensor test in hot water per WSM - should go zero ohms somewhere. Mine went no lower than 20 ohms, no good -replaced, probably burned contacts. Also worth pulling connector off thermotime switch and checking its behaviour - there is a post by Wally P somehwere detailing the resistances it should give at what temps.
Check valve is easy, so do that first please.
jp 83 Euro S AT 53k.

Luis_M

Tampa928: Fuel delivery rate should be checked at the return outlet from the fuel distributor, middle of the three lines along the bottom driver's side of the distributor. (The front one is the cold-start valve outlet, the back one is the fuel return from the WUR going forward and the return from the top of the hot-start valve going backward). For the M28.09 and M28.10 engines, you should get 1120cc fuel in 30 seconds minumum with fuel pump relay bridged (WSM 25-6e). You can also follow this hard return line out to the right side of the engine bay; it may be easier to disconnect it from the flexible fuel return line that goes down to the firewall and collect your sample here.

Fabio421: That odd item is the hot-start soleniod valve, later Euro CIS models only.

Fabio421

Thanks. I knew my 78 didn't have that part.

Tampa 928s

Making some progress, waiting on some Bosch plugs but I have a miss more apparent at idle. New everything but the car has sat for 10 Years. Fixed a few vacuum leaks had to adjust the after that running at 400 @ idle. So yes, it needs to be driven, but I want to add a little sea foam but have had two negative comments using this on a Cis system. Any feedback on this it worked magic on my 85 so I would like to give it a shot