I presume to find out the pump was working you jumped out the fuel pump relay or switched the relay manually or put a flying 12 Volts onto the pump direct.
You could try running the pump externally again but with the fuel lines connected and crank the engine over at least you know fuel is getting to the injectors. I have a lot of experience with Cosworths but not Porsche's and thats what I would be doing at this stage. Even if that worked and the car ran you would still have to find why the fuel pump relay is not getting triggered. If it didn't work then either the injectors are not working or there is no spark. Either way there must be something missing from the DME.

One last thing and please I dont want this to be a Red Herring, but i read once on a forum that if the engine is in serious danger of overheating it will shut down, I noticed at the start of your post you had an engine over heat/Gauge failure?? What was that all about. Did it ever overheat or is it a sensor problem because if the engine does ( and I dont really know) shut down with severe overheat has the sensor told the DME to stop the engine. Faulty sensor. You know, I almost want to delete that whole paragraph cos I just dont know but what if it did.
Perhaps if you post another new Thread asking those with much more experience of the 996tt than I have if that can happen with an engine overheat.

Ps I think you will find the fuel system hold pressure once the engine is off. You will have noted when you disconnected the fuel lines to the filter there was pressure still in them. Its enough in conjunction with turning the key/ pump trigger to supply fuel to start the engine.

 

I'm looking at my 996tt 2002 wiring diagram for the fuel pump and there seems to be no big surprises.
The Fuel Pump ( FP) is fed direct from Fuel Pump Relay ( FPRL) from con-tack 87 which is fed from Fuse C4
There is another fuse showing here C5 . Looks like it by-passes the FPRL for some reason. Goes to contact pin 87 on the FPRL then directly to the pump. I wonder if it comes from the iggnition switch as an initial kick to the pump when cranking?
The FPRL switching circuit is fed live 12volts from VS 100 terminal to con-tack pin 86 on the FPRL.
The FPRL is switched on/off by the dme on con-tack pin 85.
There would appear to be nothing else to stop the FPRL switching the Pump on.
Hope it helps a little.
Frank
ps I would send you a copy of the wiring diagram but its an adobe file so I dont know how to put it onto the forum. I dont seem to be able to copy & past it?

 

I don't know if you already saw that post. You can jump the fuel pump relay (Porsche tech) https://www.6speedonline.com/forums/...ost-leaks.html.
When you did your clutch did you disconnect any ground wire that was in your way? (ground point #3).

I am just thinking and writing here:
First the last thing that was done on your car was the clutch??? That is why ground points came to my mind.... Also,
I am trying to found a relation between the engine shut down and a coolant temperature sensor fault ????? Anyone (sunnyside) sees the coolant temp sensor on one of the wiring diagrams (cluster, mfi vehicle or mfi motor). I cannot???
But you already prove that you have ignition (starter fluid) .... It seems to be related to fuel supply. If I get closed to the tank I can hear the pump when its running... Did you?

Info: look at this nice post from Pumalx! https://www.6speedonline.com/forums/...-pictures.html

Info: a friend of mine had a problem similar to yours. The car refused to start. He decided to measure the amount of cc per minutes. Here's his answer: "I looked inside the gas tank, no damaged hose inside, put other pipe on feed to motor, 30seconds 50cc of fuel! should be 1.5 liters" Finally the fuel pump assembly was replaced....

 

Hi Jpflip,

Hi mate perhaps a misunderstanding I cant see any coolant temp cut off in the wiring diagrams at all, its was something I read on a forum and I really dont know how much or if any is correct.
I was wondering about the starter fluid, you dont always need a spark, if its Either fluid. It could pe-det with the compression of the engine alone. So as I earlier posted it should not be taken for granted that there is a spark. Works even better on a Diesel. I dont like the stuff at all.

Your thread about the amount of fuel delivery could be a winner. The figures you have given are what I have read in the Porsche workshop manual as well. I think Markski mention damaged pickups earlier.
I hope Mike123 tries a fuel delivery test.
Just one thought on that , he did say he had fuel at the filter, I have asked him if the engine coughs or splutters be he hasn't replied. Because even if a very small amount of fuel was in the lines the engine should give some indication with a few splutters of life.
Engine speed sensor, I wonder??? Been a few posts about that looking back on 6speed.
Lets hope he gets it fixed . Nothing worse.
Frank.

 

I have fuel coming to the fuel filter when I turn the key. I CHANGED THE CRANK SHAFT POSITION SENSOR AND THE TEMP COOLANT SENSOR. BUT THE STUPID THING STILL DOESNT START. NO FUEL COMES TO THE RETURN LINE TO THE FUEL PUMP. BUT IT SHOOTS OUT LIKE CRAZY FROM THE EXIT LINE TO THE MOTOR. What a car. lol

 

Lets re-cap here.
You have fuel pressure at the filter ( is that what you mean by exit line??), but nothing in the return line.How far have you chased fuel pressure too? You haven't mentioned if the car coughs or tries to kick over when you crank it. If it does you have a spark and a little amount of fuel getting there but not enough to start it. can you smell fuel at the exhaust? If you have crimped the return line some how when working on the car the Fuel pressure will be at Max. ( ie all the pressure from the pump cant return back to the tank so will be at Max) so you will have pressure at the injectors. If you have a fuel line problem between the filter and the injectors and no fuel is making it to the injectors then the car most likely will not kick over or cough.
I'm not too sure what is between the fuel filter and the injectors Who knows if there are valves or coolers. Will have to look at the diagrams tomorrow.
Perhaps others might know if on a 996tt fuel will return back to the tank> It has on all the other cars I have had, but I have to admit my 996tt surprises me all the time.

Frank

ps could really do with knowing if you have a spark as well.

 

You got a very difficult one to troubleshoot! Please keep us inform of every step you are going to take because I am really curious about the final income.... If you look at this picture you will found, the only thing between the filter and the injectors is the fuel pressure regulator. I never heard of a FPR failure but may be someone did. Again I hope when you are saying a lot of fuel is coming out you are talking about 1.5 liters per 30 seconds or more !!!!

 

ONE THING I CHECKED WAS THAT I GOT NO FUEL TO THE FILTER COOLER AREA ON TOP OF THE AC COMPRESOR. IM GOING TO CHECK FOR KINKS IN THE LINES. Thanks guys for everything. I will work on the 996 tomorrow with your guys tips.

 

Did you check the fuel pump relay?

 

what do you mean by filter cooler area?
I have looked at my issue of PET 107.05 24.1.2010 and can see what JPFLIP has posted.
Basically:
1. Fuel into Filter
2. out of filter to item 17 feed line
3. Through fuel Rail 1( feed injectors)
4. Through fuel hose 3 ( Bridges fuel rails).
5. Into fuel rail 2 ( feeds injectors)
6. Through fuel pressure regulator 4
7.Through return line 24
8. Into fuel cooler
9. Through fuel return line 15

If you have fuel at the regulator and the reg is defective open you will have no fuel pressure but max fuel full flow through the return line to the tank and the car will get almost no fuel. Could still just cough though. If the reg has failed shut you will have minimum flow but max pressure at the injectors. Car will definitely cough / kick ( assuming a spark) but will over fuel very quickly. You should be able to smell fuel at the exhaust and it will be easy to flood the engine.

So back to my first question , what do you mean by filter cooler area? Please be more specific as it is very easy to misunderstand over the net.
How have you checked the fuel at the fuel cooler. Have you been able to disconnect a pipe in that area??

For no fuel to get to any injectors vial rails 1 & 2 then there must be a blockage some where in 17 feed line( assuming you know there is good pressure coming out the filter) ie this is assuming that we are confident the pump is working 100% as it should when you turn the key without any jumpers or " cheats".
If you dont get at least a cough or kick with fuel pressure in Rails 1 or 2 then I really do think there is no signal to the injectors or no ht ( Spark)
Either way I would start to wonder if the DME is stopping either or both for some reason.
Might sound daft but have you checked all the fuses. Power to the DME ??
Frank.

 

When standing at the rear of the car on the left hand side fuel comes to the fuel filter. I tested it by opening the bleeder cap. Fuel only comes out of the bleeder when I start the car not when the key is in the position right before you start the car. When I open the fuel cooler lines no gas comes at all to that area. Does anybody know if fuel should come out of the fuel pump when the key is turned right before the start position?

 

I have just been out the the car and took the union off thefuel filter. Yes on the first attempt I got about 30ml of fuel out with the key in position 2. One quick pulse then stopped.
I tried another 4 times and it didn't do it again. Maybe on some timer to stop pump damage. Who knows. But what I do know is that even after dropping all the pressure form the system the car started instantly I turned the key to the starter position, it didn't need to be cranked a few seconds to build up the pressure again before it fired up. So even if you dont get a pulse of fuel with position 2 if the pump runs when cranking you should have fuel to start the car.

This has got to be one of those faults that gets printed off once you have the answer.
Phew...not easy.
Frank

 

I just checked feed line 17 and gas does get to the injectors but it doesnt circulate to the return lines attached to the cooler. Does that mean the fuel pump is not working correctly? (MEANING THAT IT DOESNT FORCE THE FUEL THROUGH THE LINES WITH ENOUGH PRESSURE?). THE CAR DOES COUGH A LITTLE.

What I need tio find out is if power should come to the fuel pump when the key is in position 2? lol

 

That's better, now we know it coughs so you have HT.
As I posted above Yes I had one pulse of fuel in position 2 then nothing, no matter how long I left the iggnition turned on.
I am going to do the test again...ie undo the fuel filter union and see if i get another pulse of fuel.
I would think that once the pump is running continuous it will pas through the pressure reg and fuel cooler.

You are going to have to do a fuel delivery test. it should be 1.25 ltrs in 30 seconds . This info is direct from the workshop manual 22 66 01 " Checking quantity delivered by fuel pump"

And do a fuel pressure test: 3.8 bar.
Now I dont know how to copy and past from an adobe file so I cant send you a copy of the maintenance sheets. I wish I knew how. I am not going to write it up as any mistakes could be dangerous there are safety precaution to observe

Basically to test fuel flow you disconnect the fuel line say out of the filter , hold the pipe in a measuring jar and get a friend to short out the fuel pump relay to run the pump continuously for 30 second. Remember to remove short link. There are loads of general fire and safety precautions so I am not condoning you doing it as I dont know exactly how you will do it.

For pressure testing basically the plug/cap you called a fuel vent is for pressure testing. Its where the gauge goes. Once again with a suitable gauge and piping jump the pump relay and get the pump running. Measure the pressure.

Frank

ps sorry I am not very good with instructions especially over the web. I'm more of a " move out the way and let me get my hands dirty "guy. Its hard not being there with you.

 

I cant get your problem out of my head.

I keep getting this nagging feeling that if your pump is ok then the answer to you problems lie buried somewhere in your very first post.You have the clues we just dont see them. Or something you have done just before the problem started might be the cause.
This would have been a very long journey to end up at the start again.LOL
I think 1st Pump....must do some checks.
If you cant do them, get an Indy to do them. Its time to get some pro help before you spend any more cash on other parts etc.
Frank