Fuel tank 911 SC - unblocking feed and return pipes

[stormlister]

I have removed tank from my 911sc as I suspect blocked pipes. I have steam cleaned and flushed tank quite a few times and roddled pipes. The outflow pipe seems cleaner now with a good flow. I am not sure if return is clear or not. When tank filled with water it only drips out. Is this normal or should there be a flow?

For the return pipe. I am using a stiff but flexible wire based rod but it just stops against something very hard. My understanding is that the return pipe is a straight thru pipe into the swirl. is that correct? I should be able to pass a rod into the swirl area. is that correct? when filled the outflow of the return and main outlet should be about the same? is that correct?

I have spend many hours flushing and rodding. I am getting close to giving up and resorting to a new tank. any advice appreciated

[JSZ]

I have been through this issue, the memories are still raw. Short answer the return and supply will need to be free flowing, otherwise the CIS system will not work and shut the engine down.
Sent you a PM

Jeff

[stormlister]

Yes. It is very annoying. Car idles and refuses to rev. Like you say also shuts down.v We replaced fuel pump, fuel filter and then tried another Fuel head to pretty much have the same problem. We then noticed poor flow in the tank feed and no flow in the return, which is why I removed the tank for flushing. I cannot get anything flowing in the return pipe so I guess its seriously blocked. I don't see how I cannot unblock this pipe.

[nomore]

Research photos of swirl pot, doesn't look like a straight shot.

[boyt911sc]

Originally Posted by stormlister

Yes. It is very annoying. Car idles and refuses to rev. Like you say also shuts down.v We replaced fuel pump, fuel filter and then tried another Fuel head to pretty much have the same problem. We then noticed poor flow in the tank feed and no flow in the return, which is why I removed the tank for flushing. I cannot get anything flowing in the return pipe so I guess its seriously blocked. I don't see how I cannot unblock this pipe.

Storm,

You need some sort visual inspection to clean and remove the debris (if any) in and around the swirl pot. The return line has two (2) 90° elbows or bends before it enters the swirl pot. Without cutting an opening for visual inspection, a bore scope camera does the trick.

Search for pictures of the swirl pot so you could visualize how the delivery and return tubes configuration (bends and location) look like. If you fill the tank with water and allow to drain, both deliver and return tubes should have free flowing water of almost equal rate (theoretically) because they have same size ID tubes. If the flow rates are significantly different or slow, there is flow restriction.

Tony

[Mark Salvetti]

This thread has some good photos of the swirl pot removed, so you can see that there is a narrow circular channel that feeds fuel to the pump.
CIS Gas Tank

I bet that is gunked up. If that's the case, it's going to be hard to clean out.

You might be able to get to it through the strainer opening with a thin brush or maybe a coat hanger.

Mark

[Adrock]

Did you end up cleaning out the pipe? I'm having the same problem and can only get a wire halfway down the length of the pipe. I've been spraying brake cleaner down there and digging it out with a wire with a small loop on the end - it's taking forever!!
I can finally blow some compressed air down there and can actually hear it coming out into the tank, but not freely. Does anybody have any more suggestions how to clean out all the caked on goop that's in there. It's like it's set solid.
I'd just go and buy a new tank - but I stupidly cleaned, treated the rust and painted the tank before I checked to see if the lines flowed freely (never driven the car).