DDK - Die Deutschen Klassiker

SeanP wrote:

dlampard wrote:Hi Sean P,
New inline fuel filter.
Haven't checked the fuel quantity by doing as you mentioned but will do so and report back.
Not aware of a fuel mesh from the tank but that's not say there isn't one. Something else I will have to check.

https://www.rosepassion.com/en/cat/pors ... -mm/P12948

This is the in tank filter I am on about. If the tank is not clean, (sediment and rust in the bottom), as the fuels passes through it can drag the sediment onto and block the filter, hence the fuel starvation issues

Regards

Sean

Will take a look at that too. Do I need to remove tank to get to this or just under the car?

Jack up car and support it
Remove under tray.
Find fuel pipe that Nick Moss suggested changing.
Remove pipe and drain tank into suitable container.
Find outlet on tank and that is the tank filter.

My link has a Parts diagram at the bottom of the page

Sean

Will try this at the weekend. Thanks again.

Marcus[/quote]

You had an electric pump feeding into a mechanical pump. We simply took the mechanical pump out of line once we had confirmed that the electric pump was working correctly.

Let me know when you are free to bring the car over to have a proper look.

Regards

Sean[/quote]

Thank you very much Sean thats really kind (again)! I will drop you a line to see when might be good for you.

Best,

Marcus

Seven wrote:Marcus

You had an electric pump feeding into a mechanical pump. We simply took the mechanical pump out of line once we had confirmed that the electric pump was working correctly.

Let me know when you are free to bring the car over to have a proper look.

Regards

Sean[/quote]

Thank you very much Sean thats really kind (again)! I will drop you a line to see when might be good for you.

Best,

Marcus[/quote]

Marcus I had this too on my 912. The electric pump was filling into a mechanical one. There are two approaches.

1) By pass the mechanical pump. To do this just buy some more hose. Then decide if to leave the mechanical pump on or just get a plate to block off. This is what I currently have

2) By pass the electric pump. You can buy a rebuild kit for the mechanical pump and Bruce Smith in the states can help you with any parts that are worn.

I suggest you go for 1) and rebuild the mechanical pump as a back up?

I am in the process of going through the fuelling system on my car as I suspect some of the fuel lines may be originals! Absolutely solid with no flexibility in them. I am going to replace the braided fuel lines with Gates R9 fuel line which supposedly deals with the Ethanol content in modern fuels better. Don't forget the wee bit of flexi hose on the solid lines behind the fan housing. I imagine most 356s and 912s are running around with 50 yr old fuel hose just waiting to split and spill fuel.

I am prepared to sacrifice a bit of originality for safety.

You may want to blow out the solid lines with air also. If your rubber lines have fallen apart you may have a blockage?

I am also going to rebuild the fuel pump and carbs in time.

The mesh filter in the tank unscrews from the tank as previously stated. Be careful with it as they are not cheap. I soaked mine overnight in 5% distilled vinegar and it came up all sparkly with all sorts of fine crude in the bottom of the vinegar bath.

Matt

wildtexas wrote:I am in the process of going through the fuelling system on my car as I suspect some of the fuel lines may be originals! Absolutely solid with no flexibility in them. I am going to replace the braided fuel lines with Gates R9 fuel line which supposedly deals with the Ethanol content in modern fuels better. Don't forget the wee bit of flexi hose on the solid lines behind the fan housing. I imagine most 356s and 912s are running around with 50 yr old fuel hose just waiting to split and spill fuel.

I am prepared to sacrifice a bit of originality for safety.

You may want to blow out the solid lines with air also. If your rubber lines have fallen apart you may have a blockage?

I am also going to rebuild the fuel pump and carbs in time.

The mesh filter in the tank unscrews from the tank as previously stated. Be careful with it as they are not cheap. I soaked mine overnight in 5% distilled vinegar and it came up all sparkly with all sorts of fine crude in the bottom of the vinegar bath.

Matt

"Took my 68 car out today for a run. About 8 minutes in I came up to a roundabout and slowed down which then produced a loud 'slapping' bang. Car didn't stop as I managed to keep going on to a slip road but under acceleration the car was hesitating. 2 further minutes I came off on to slip road and had to stop at roundabout to allow cars to go round.. At this point my car decided to stop and refused to start. I noticed that I had loads of bubbles feeding up back to the fuel filter as though it was boiling. Took about an hour or 2 to get it going again which involved sucking fuel through, filing rotor arm, points (tried everything). Not sure what did the trick."

I'm not sure about the boiling fuel but this sounds like an ignition problem to me. I check the points gap and dwell angle over the rpm range. Then checks the max advance. Then replace each spark plug and check the leads.

To add my personal view.
I would go with the electric fuel pump (my personal preference) It has the benefit of priming the carbs before you try to start your engine. A note of caution, use a timer relay that fires the pump for up to 10 seconds, but then shuts off until it sees a pulse from your ignition system. This adds a little safety in case of a crash etc

Its simples and should cost no more than £10

As per all the above- work through all service items first, then identify if its fuel or ignition related etc etc if the problem persists

Martyn

Could well be blocked mesh filter in tank if you have rust in the tank. My car suffered from this when I first got it, it would run OK until you put your foot down then the suction would pull all the rust flakes in the tank up against the mesh and stop the fuel from coming through, it would bog and stutter (usually just as you were trying to overtake something!) as soon as you let off the accelerator the rust flakes would drop back and allow you to accelerate again (gently).

This doesn't particularly explain the loud slapping bang though, which could be attributed to unburnt fuel exploding through your exhaust if you lost spark somewhere.

neilbardsley wrote:

Seven wrote:Marcus

You had an electric pump feeding into a mechanical pump. We simply took the mechanical pump out of line once we had confirmed that the electric pump was working correctly.

Let me know when you are free to bring the car over to have a proper look.

Regards

Sean

Thank you very much Sean thats really kind (again)! I will drop you a line to see when might be good for you.

Best,

Marcus[/quote]

Marcus I had this too on my 912. The electric pump was filling into a mechanical one. There are two approaches.

1) By pass the mechanical pump. To do this just buy some more hose. Then decide if to leave the mechanical pump on or just get a plate to block off. This is what I currently have

2) By pass the electric pump. You can buy a rebuild kit for the mechanical pump and Bruce Smith in the states can help you with any parts that are worn.

I suggest you go for 1) and rebuild the mechanical pump as a back up?[/quote]

Hi Neil & thanks very much for the reply.

Good to know my setup was not the only one like it out there!

Marcus

Ok, carried some of the recommendations today.
Checked all hoses and replaced as necessary.
Took fuel tank out in filter. Have a good clear out but not much crud in there at all and filter was clear.
Changed fuel filter again.
Cranked car over with fuel line off from mechanical pump and all working fine.
Took it out for a drive again and after a while of driving I came up to a junction and once again the car died and wouldn't start.
Same as before- bubbles coming up into the fuel filter.
Lost as what to do next.

When this happened was it the first time you have used the car this year?( I'm thinking stale fuel) If the car was ever ok and then it started playing up did you do anything that may have caused the change? Have you noticed the bubbles before ie when it was running ok? If its dying, your carbs are running out of fuel (float levels?) or its an ignition problem. Sorry not much help but you will have to go through everything to eliminate till you find the source of the problem. Good luck Simon

Rebuild the fuel pump. Sounds like the non return valve is stuck open and then check the carb float heights to ensure they are correct.

Sean

Been looking on other forums and pretty certain it's vapour lock the car is suffering with. Will look to see how I resolve this.

Bubbles in the fuel are not necessarily a problem.

http://forum.porsche356registry.org/vie ... =1&t=27960&