Porsche Enthusiasts Club Forum

I had put this on hold for a while and sadly the S has been sat under a cover on the drive for a good few months now and I think I need to get these fuel lines sorted now that the weather may be turning better?
I had made up some new fuel lines from cunifer but they got put to one side due to not being able to get the 944 in the garage and the poor weather we've had over the last few months.

This is how far I had got in December

This will be the set up once the cunifer is in line.



Shaping the pipes using the old ones as a template.





So to a question I had when I stripped the old fuel lines out, I pulled the rubber return hose out from the top of the tank sender which didn't come out easily, I removed it because I wanted to replace it with a new hose but when I tried to push a new pipe down the same space it wouldn't go. I also tried a 5mm flexible rod, which I had planned to push through, tape to the new fuel hose and pull through, unfortunately the 5mm rod wouldn't even go through, I think it is catching on something. This is as far as I got in mid December so gave up.
To replace the rubber hose I mentioned above do I need to drop the tank and subframe to give some room? I am going to have another go at this on Sunday as the weather looks okay, so I'm planning what to do in advance and then will see how far I can get?

The return line to the tank, a real pain if you just pulled it out without something attached to itthinkit get stuck on the top of the tank and gearbox support

Hi Infasilver,
As you probably know I did something similar with my 944. I did connect a length of nylon rope to the old pipe before I pulled it out but when pulling the flexible pipe back I don’t remember it being too difficult ie the route it took wasn’t that torturous. I think you’d definitely need 2 people doing it and to use some stiffish electrical cable. I would go from the top of the tank in the boot pushing it down towards the underside and not the other way. The gaps aren’t very big and I could feel my rubber hose rubbing all the way when I pulled the new one back through.
One thing that I think is important to note and I would have done differently had I known when I did mine is that the correctly sized rubber fuel injection hose for the 8mm return pipe has an internal diameter that is too small to fit over the steel? fuel tank inlet pipe on top of the fuel tank. I had to make a copper reducer that allowed me to go from the smaller diameter rubber pipe to the larger diameter rubber fuel pipe I used on the 10mm feed pipe. (Just soldered up some standard plumbing microbore fittings) what I would have done differently is added an 10mm adapter at the end of the 8mm kunifer pipe and used the same sized fuel hose I used on the 10mm pipe to go all the way back to the top of the fuel tank.
Someone more knowledgeable than me may know why it is an 8mm return? Is that just for reasons of economy and in fact using the same 10mm Kunifer and rubber injection fuel pipes would be ok so simplifying everything by doing both feed and return in 10mm or is it a pressure thing too.
Just thinking this might help others in the future.
Otherwise good luck Infrasilver.
Brett and Sam.

Trying to refit the return line was one reason I gave up for the time being as I spent a couple of hours trying to get the new hose fitted back where the old one came from. I just wanted the whole system removed and I didn't think to pull in a cord in when I removed the old one.
I have a really good flexible 5mm fibreglass fish tool with a brass end but even that doesn't find its way through, it goes the same distance every time so it must be hitting the same thing each time I try!
I was thinking there must be a knack to it but maybe perseverance (or luck) is the answer but I can see me just coming to the same stop point as before.

I need to get the 944 running as I've just finished rebuilding my 996's engine and it's ready to be started up and run in but the 944 is in front of the garage, both cars are stuck where they are until I can get these fuel lines fitted!

I’ve had a lot of luck in these situations using a length of pallet strapping. You can often find unwanted pieces at building merchants etc. Just because it flat and flexible.

And very very strong

I didn't have any of that packing strip available so carried on with the 5mm fish, this was how far I was getting down, to the black mark about 10 inches down, not enough to see the end and I couldn't see what it was catching on.



It wasn't working still, I had a hunt around the garage and couldn't see anything that would be thin, strong and flexible enough to go past the point it was sticking. Then it came to me, I had some extra large cable ties in a cupboard in the house.





I tried that and after a bit of wiggling I got it past which allowed me to tape the pipe to the end and slide it through, I had to WD it to make is as slippy as possible and it was still a little tight. The first attempt broke the tape but with more tape around it the second time it was successful.



Thanks for the tip with the thin plastic strip, I think this should help me get the fuel lines all fitted tomorrow and fingers crossed running again.

Great news. Such a relief when you’re doing it on your own and you have a bit of success. Like the hard line to hose connections too.
Are you renewing or rerouting the fuel hoses in the engine bay?

I did make all the difference using the thin plastic to get through. I haven't changed the over engine flex lines, I have inspected them and they are fine, it may be something I look at soon though.

I got all the lines fitted on Sunday but didn't tighten them up until Monday but all looking good so far. I also used clear shrink down tubing, the same as the brake line where it goes under the chassis rail just to protect it at the rubbing points.









My intention was to fire it up today and had already boosted the battery in readiness but after turning over slowly I think my battery is dead as it hadn't taken the charge, a new one is on order. I pulled the new Bosch battery from the 996 and it turns over really well with that but just wouldn't fire up, I undid the fuel rail hose and fuel came out, the return line also had fuel coming out of it after it was loosened, both under pressure so the pump seems to be pushing fuel under pressure.

I then turned to the basics of knowing I had fuel so next checking for a spark which was also there, I swapped the DME relay and again it just spun without firing. I ran out of time to get any further but will need to dig deeper tomorrow and eliminate anything I can think of. I did pull a spark plug and expected it to be wet with fuel but it wasn't so maybe the injector isn't pushing fuel through but will update again in the next couple of days.

Watch for the tacho bounce when your starting, that will tell you if the crank sensor is working
You can also bypass the dme relay with the 3way wire bridge

I will dig a little deeper this afternoon, bit annoying that it didn't fire up but it has been sat for a while so I guess it could be a dodgy connection?

You also need 2.8 bar in the fuel rail for the injectors to work, you did mention plugs dry, will take a while to build pressure

I ran through jumping the DME relay positions and had the fuel pump ticking but still didn't start and I made sure all the injectors were working using a 9v battery to click them several times all seemed fine and I started to scratch my head as I couldn't think of anything else it could be.

I ran back over the fuel lines and found I had mixed up supply and return lines going over the rear subframe, DOH!!, I feel like an idiot now.

At the weekend I had been putting the connectors together before getting back on this and because the new fuel lines had been hanging under the car since the last time I had worked on it I made up the rubber hose return line with a 10mm compression fitting instead of an 8mm fitting and this led me down the garden path and I have then fitted the 8mm line to the supply. So the reason it is not starting is because the fuel pressure is coming in the wrong way through the fuel rail and pressure relief valve!

The moral of the story is, don't leave it 4 month inbetween making up all the fuel lines and then fitting them!!!

I eventually got it running yesterday after rectifying my school boy error and swapping the fuel lines over, I actually made a better job of it on my second attempt. Found a couple of joints weeping but nipped them up and it's all sealed now.

As it's been stood for a few months I found the exhaust split where the pipe goes into the centre silencer, so I welded that up rather than go to the expense of a new exhaust system.

But I have also noticed my temperature gauge isn't working, I was going to just order and replace the sensor to eliminate that as I hadn't replaced that in my ownership but before I bought a new one I noticed the price of them, nearly 85 quid, I was quite shocked at that. So I was wondering if there is a common problem that it may be before I spend big on a new sensor? I guess checking the resistance of the sensor and maybe checking the needle isn't stuck in the gauge?

And cleaning the brass rugby ball shaped connectors on the back of the cluster

And it’s not the blue connector at the front it’s the one a bit further back