996 won't start after sitting for 5 years

Dear 996 enthusiasts Unfortunately I was in the situation that couldn't use my beloved 996 (996.2, 2002) for a long period of time, but times have changed and I am ready again. I would like to give you some information first. Engine was completely rebuild (IMS, oil service, filters,..) before I out the car into garage. The car has driven 120.000km (75.000 miles), automatic transmission. It was last started 2 years ago without any problem. Couple of weeks ago I wanted to start it again but it just cranks and doesn't want to start. I assume the fuel is very bad so my plan is to drain the fuel out of tank and start from here. Option 1. is to bypass the fuel pump relay, connect the hose to the fuel pump and pump the fuel out this way. I have heard that in this care some fuel remains in the tank so there is Option 2. to open the fuel filter cover and pump the fuel straight from the fuel tank. What do you think? My next step would be fresh fuel, start spray and give it a try. Should I be careful with some other things? I can hear the fuel pump when I turn the ignition, the RPM moves a little while it cranks so it shouldn't be a crank position sensor. Thank you for any suggestions and sorry for my broken English Have a great day! Best regards, Blaz

I'd drain as much fuel as possible using option 1, then fill with 5 gallons of fresh 93 octane fuel. That should dilute the fuel still remaining in the tank enough to get the car started. I'd drive more cautiously until you completely fill the tank...maybe even until the next tankful. You may also have clogged injectors due to old ethanol fuel being left in the injectors. Also, change the oil in case any fuel has leaked into the cylinders and then into the sump.

The fuel in there is old. I would recommend manually removing the fuel via the fuel pump access under the battery. good time to make sure the fuel pump is in good condition as wells as the interior of the tank. I this checks out, fill with new fuel. I would purge the fuel line also by disconnecting in engine bay. I would scan the car for codes. If all checks out, then crank it. Lastly, since car has fresh rebuild and condition is known, I would replace all injectors before ever trying to start it. If it was a **** unknown car, I would not bother with injectors. since ur car is fresh, I think injector replacement along with full fuel system clean is very important. All that said, a good buddy started his c5 corvette after 10 years of sitting. Fires first crank. He didnt care. Was doing an engine out to replace clutch.

So, today I have manually pumped out the fuel through the fuel pump opening and refuelled 15L of fresh 100 octane fuel. I have managed to start the engine only with a help of start spray in the air intake. The engine was running for couple of seconds then it turned off. At least the sound was nice while it was running. Sorry, I haven�t read your reply before doing it, so I tried to start it anyway. Should I somehow clean the fuel hose from fuel pump to the engine? Do you think the old fuel was already burned/used out of the fuel system after the engine was running for 5 seconds let�s say 5 times in total today? Problem is definitely the fuel but I am not sure how to continue Thank you very much! Best regards, Blaz

Well its good that it started on the spray. U need to check for fuel pressure. Most parts stores will rent the tester out or u can get them from amazon for under $40.

The injectors are most likely stuck and dont open even though they receive 12V pulses, as teh engines runs on starter spray. Old Fuel has been replaced and pushed back into the tank through the return line during cranking. If you can reach the injector bodies using a long thin screw driver or a mechanic's stethoscope you can listen if you hear the injector clacking away when the engine is being turned over by the starter motor. If not, then tap the bodies using said screw driver and tapping its handle with a plastic or small hammer whilst the engine is turning over. This can free the injectors. Removal and ultra sonic cleaning them and then run them in a test Set up will free them no doubt. I recommend removing spark plugs to see if they are wet with fuel or bone dry.

You are getting some good suggestions, but you need to slow down and just go back to basics. It runs on starter fluid so you know you have spark. Whether the car is fuel injected or carburetor, you still need fuel to which ever. Either get a fuel pressure tester or go crazy and just pull the fuel line of the rail, have someone crank it and see if you are getting any flow. That will tell you whether the pump is any good in the tank. If you have fuel, than move on to injector issues. I doubt you have any.. For all 6 to fail is pretty unlikely. It would run on a few cylinders. If all good, that clean fuel will help things. Don't just throw parts at it without knowing what EXACTLy is needed. People tend to complicate this process. Start over with the basics than come back and tell us what is up

You have fuel issues and there are only 2 of those. 1) fuel pump, 1) injectors Fuel pump is cheaper. Good luck

Not sure if this was mentioned but check fuses for Fuel Pump and Injectors.

Reference this thread ( https://rennlist.com/forums/996-foru...-location.html ) for fuel pump relay location and bridge pins 30 and 87 to ensure that the fuel pump is running. My fuel pump relay died suddenly and that got me home (I know you are just trying to start it). You can also refer to figure 2 on this Pelican Parts page: https://www.pelicanparts.com/techart..._Fuel_Pump.htm

Agree with checking to see if the fuel pump is running.

Drain the fuel whichever easier for you, fill with fresh gas, put some injector cleaner in it at the same time. Change the oil (I would change it a second time once you're able to get the car started and able to drive it for a bit). Get it up to temp (do a few heat cycles) then drive it. I would also recommend checking the anti freeze as well as probably switching out the brake fluid. Everything sitting that long and not being used should be switched out. Report back and let us know how it goes.

Hi guys, thank you for all the replies. It�s the pump, no signs of life As I am from Europe, do you have any experience with some alternative brands, because original fuel pump costs 600+�? I can get VDO (Continental) A2C52124455Z for 280�. Thank you!

No experience but i would bet that the vdo is the oem. It not that hard of a repair so i would take the chance.

Thanks for the update! Does the pump receive 12V when cranking? Check the fuse, if you've not done so already. Does the pump run if you feed it with a charged battery directly? Perhaps it's stuck and it needs a jolt and a tap to start spinning again. However, I fully understand, that even if it kicks back to live, it does not provide the confidence that it will reliably run on turn of the key in the future. No personal experience but I would feel confident to buy a pump from continental. Even more so if it says bosch or pierburg on the box.

The pump receives 12V, I have also connected it directly to the battery but nothing happened, just sparks⚡️ I assume buying a new one would be the best idea. I�ve found some cheap one from Germany for 180�, but not sure about the quality. Probably better to go for Continental. https://www.mhteile.com/p/porsche-ht...fUtx11xX56x9wn Best regards, Blaz

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A couple years ago I bought an Audi TT that sat for 5 years. The fuel pump(s) and their wiring deteriorated to the point that the car would not start. I sourced Continental fuel pumps to replace them. They've worked fine for the past 2 years. I'm curious what else you will find. In my case I had a couple of vacuum leaks that I had to take care of (cheap plastic connectors & tubing) and somewhat surprising to me at least was that all 4 shocks were totally shot from sitting.

Quote:" surprising to me at least was that all 4 shocks were totally shot from sitting" Dis-use of the human body causes atrophy in muscles and weakened bones too. I don't expect cars to do any less. I brought a Ferrari 355 back to life after sitting for 10 years and everything hydraulic needed replacement.

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Sounds like the way this vehicle was stored had more to do with the issues than time. I�ve had to deal with cars sitting outside for years and years, versus cars stored in climate controlled spots indoors.

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Good comment. My TT was stored under cover in an airplane hangar in Texas for 5 years, prior to my purchase. So while it was out of the elements, it did experience the humidity/temperature of a Texas environment for 5 years, sitting still.