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2.4T MFI first start-up for a while and new fuel tank

Posted: Mon Oct 26, 2020 10:32 am
by deano
Just going through a few procedures before starting my engine for the first time in maybe 5 years, since removing the fuel tank for front end panel replacement.... was set up and running good before this...

So, who things this old bugger will start on one battery charge?

So far, I have:

- cleaned out the new tank as per manuf instructions, cleaned the fuel outlet gauze.
- pulled the plugs (all black and wet, and one had a bad gap but maybe it was boinked on the way out)
- engine turned freely by hand
- bore-scoped the pistons through the spark holes (out of curiosity since I was using the camera anyway, and through paranoia because I once found some pieces of a plastic intake inside on another engine)
- Biro test on MFI pump - rack moved freely back and forth

Next steps are:
- disconnect the MFI pump fuel feed and place the hose in a clean glass bottle
- put 5 litres of 99 RON in the new tank, operate the fuel pump and dump fuel into the bottle (hopefully!)
- reconnect the pump fuel feed and put the fuel back in the tank, operate the pump again to fill the pump.

HAVING TROUBLE with 2 things at the moment:
I want to pull the 3-pin CDI connector before cranking for the first couple of times to build oil pressure (hopefully!)...
- however, the connector will not budge - is there an alternative way to disable the spark? Many thanks to the Porsche engineer that decided to put one of the bolts for the CDI panel right behind the 3-pin connector!!
I want to fill the MFI pump with oil... it appears that the traditional way to do this is to fill it through the oil return (see attached pic) that connects to the breather. The rubber hose section doesn't want to budge either, but I am thinking of 'cutting' it off and replacing it with new hose.
- has anyone tried to get a new joining hose section on with the pump and breather in place? I am a bit worried that its going to be a royal PITA.

Following on from that, I am taking some advice from Grady Clay's suggestions in these posts primarily:
http://forums.pelicanparts.com/porsche- ... k-mfi.html
http://forums.pelicanparts.com/porsche- ... e-mfi.html
- you might notice a small contradiction, or alternative procedures, in Grady Clay's suggestions for enabling/disabling CDI and fuel pump. I am going with fuel pump on and CDI off for initial cranking so that the injection pump get fuel fed during cranking:

Does the following procedure look good to you?
- crank the engine and check for oil pressure build up with fuel pump off (but injection pump primed with fuel first) and CDI off (or alternative way to turn off the sparks).
- loosen the injector connections at the injectors, one at a time to the expel air (faster) and crank again with fuel pump on. I'll be soaking up the fuel with paper towels or funnelling it into a jar if possible...
- reconnect everything and try to start the engine.

I'll keep you posted - any suggestions or advice warmly welcomed :cheers:

Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Thu Oct 29, 2020 4:59 pm
by deano
After syringing in some motor oil under the ends of the MFI pump oil return hose, I managed to wiggle/slide the hose down over the mating bent pipe section. I then syringed in about 0.25 litre of oil into the pump. After following the remainder of the pre-start procedure (see my restoration thread for more details), it fired up on the first turn of the key... and idled smoothly!!! Mission accomplished!

Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Thu Oct 29, 2020 5:00 pm
by Lightweight_911
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Excellent result !! :cheers: :cheers:

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Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Thu Oct 29, 2020 8:00 pm
by Jonny Hart
Sounds like a result! For future you can just pull the spade connector off the side of the distributor to stop the CDI firing.

Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Thu Oct 29, 2020 8:32 pm
by deano
Jonny Hart wrote:Sounds like a result! For future you can just pull the spade connector off the side of the distributor to stop the CDI firing.
- doh! thanks! I think you might be the CDI retrofit chap?

I think you might be talking about the output terminal from the CDI box? I read somewhere in one of the manuals that the CDI shouldn't be fired without being loaded, so I didn't. I wasn't sure about removing the ground terminal (D) or not either - it still whistled as normal when disconnected, but I suppose the primary winding in the coil would not be charged up and would not produce spark on the secondary side. Again, wasn't sure, so I played it safe.... Do you know if it is one of the winding's inside the coil that whistles when switched - I have heard this kind of noise before in large switched air core inductors?

Thanks for your input and all the best! :cheers:

Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Thu Oct 29, 2020 10:08 pm
by Jonny Hart
No, I mean remove the wire at the distributor. With it disconnected, the box won’t fire as there is no signal from the points.

Btw, there is no concept of coil ‘charging’ in a CDI system. It’s the capacitor in the box that charges up.

Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Mon Nov 02, 2020 9:40 pm
by deano
OK, thank you ! There are three wires connected together on the side of the distributor, but only one wire goes to the CDS, so I think you must be talking about that one... anyway, a good plan for next time. The engine will be on the floor by this time tomorrow!

Re: 2.4T MFI first start-up for a while and new fuel tank

Posted: Tue Nov 03, 2020 2:21 pm
by deano
Don't you just hate that inevitable small oil slick that ends up on the garage floor whenever you (have to) drain the oil !! :lol:

I wish someone would invent some kind of a tap to replace the standard sump plugs !!