So I check my fuel pressure at the pump and I'm showing a minimum 100 psi (actually beyond what my gauge will read ) but at the rail I'm showing about 10 psi dropping to 0 as I attempt to accelerate . I'm getting the same readings everywhere I check on top of the engine not just the check port, I've already replaced the damper and the fuel filter is also clear and I know I should be showing 36 or so psi at the rail, the regulators appear to be good and I know I have good vacuum on the damper and both regulators but this appears to explain why my car ( a MY 1984 ) appeared to be starving for fuel (turn out she was telling the truth but who knew ) any suggestions would be appreciated!

 

How did you measure "fuel pressure at the pump" ? With the pump just connected to the gauge and nothing else ?

 

You say you think the regulator is good. Briefly clamp down on the return line where it exits from the regulator, run the fuel pump and see what the pressure is up at the rail.

 

I attached my gauge to the hard line that feeds the inlet side of the filter . I had already tested the pressure at the rail, on those results I assumed I had either a stopped up filter or a bad pump so , to the back of the car I went , pulled the filter and blew it out , then checked the pressure off the pump as I described in the first sentence. I wasn't able to use the check port at the exit end of the pump as I'm having to use the rubber hose and clamp method to attach my gauge (no correct adapters in my end of Tennessee apparently, but as of last night I was able to buy tools to make my own adapter, necessity is the mother of invention) so I put everything back together ans start the car which was still having the same symptoms of fuel starvation, so I check the pressure at the rail and again see the same readings as before. I then check for vacuum at the damper and the regulators (had good vacuum) so I then pull the hard lines that run the between the damper (brand new) and the rails to see if maybe one or both of them was clogged (nope) and checked the pressures at every point of connection between and got the same 10 PSI dropping to 0 everywhere. It occurs to me that the problem has to be somewhere between the damper and the pump, any ideas?

 

I will try that Bill but everything I checked last night suggests I'm losing pressure before fuel gets to the regulators and to be clear because i now wonder if i'm getting conflicting information on these cars is there one damper and two regulators or is it 2 dampers and one regulator? I know there is one damper at the front of the engine and one regulator at the rear of the engine on the passengers side rail but what about the one on the drivers rail? is that a damper or a regulator ?

 

Scratch my last question Bill, I just found the diagram in the WSM its the regulator for cylinders 5-8 also i forgot to add that I had the tank off 3 weeks or so ago and it was pretty clean on the inside and the mesh screen was pristine.

 

A regulator will have a return line to send gas over the amount needed back to the tank. A dampner won't.

 

Has the car run Ok previously ? New to you ? Sudden problem ?

 

No John the car hasn't run okay previously and it is new to me also. I bought it in may of this year and basically it apparently has had every possible problem with the fuel , ignition and intake systems . So far I (with a lot of help from my Father) have had to pull the tank twice attempting to repair a horrific leak in the return line which ended with us cutting out about 4 feet of the line and replacing it with braided line during all this we discovered that the tank saddle was missing having either been removed by the PO or rusted off is unclear so also had to build a set of straps to hold the tank in the car since I didn't feel like the single bolt at the filler neck and the vent lines were quite sufficient to hold the thing in safely (I've since been able to replace the original saddle thanks to Dan Brindle) I've also replaced the vacuum advance on the distributor and the green wire, though as of last night I discovered that I actually have no vacuum at the distributor even though I pulled the plenum and replaced all the broken and dried out rubber under there, so apparently I either missed one or have a completely separate issue to look for , I also replaced that fuel pressure damper at the same time as the vacuum advance since the diaphragms were busted on both and the damper was allowing fuel to flood the vacuum system (fun! I was very excited to find that!) I just replaced the Air Flow Meter last Thursday (big help) and oh I almost forgot the very first thing I did which was to reattach the exhaust that the PO had unhooked because someone told him that his catalytic converter was stopped up (it isn't) and unhooking it would help with the flooding problem he was having (It didn't, but hey never mind all that other crap lets just make the car run so's he can drive it! ) he never did get to drive it anywhere but around his yard since that didn't fix the flooding. But unlike that guy and the 3 PO's before him I have driven it! It took me all of 6 seconds to fix the flooding, I simply reached in and plugged up the air flow meter and the flooding immediately ceased ! But then had no power which led me too the leaking fuel line, which led me to the vacuum advance , which led me to the AFM , and so on!

 

Ok James, you've had a hard introduction to 928 ownership :-)

Soemthing is clearly limiting the flow capabilty of the system. Maybe look for a crushed fuel line under the car or even in the engine bay ?

 

its all good John I spent a few days looking around on this site and pelicans boards so I was expecting a degree of difficulty in getting it running and am heading to the garage now to look at the lines thanks for the suggestion

 

May also be internal corrosion in the delivery line which is restricting flow/pressure ... it happens.

 

James, what city are you in?

 

Connecting a gauge directly to the pump outlet just tells you what pressure the the pump can generate against a blocked line. You should fit a T in the line (Gauge on the stem)so you can see the line pressure being seen at the front , where the pressure is being controlled by the regulators up front. Have you checked the delivery rate is OK- this will tell you a lot more? If its low, thats your problem, and that would be my guess. Have you checked the input to the pump is clear?
jp 83 Euro S AT 54k

 

You have one damper at the front and two pressure regs at the rear. check pressure at the main feed line at the engine...passenger fender before the pressure regs. alspo check the part # on all three damper two press regs to KNOW what you have since several people have been "fixing" this car.