Porsche 981 high pressure fuel pump

[@tawaspt]

Jeff, thank you (from Texas, USA) for this (and others) fantastic video! Thanks especially for your tip of lowering the engine (I lowered mine probably mine 1.5 - 2" (~35-50mm)) and gained enough room to be able to remove and reinstall the HPFP without disconnecting any coolant hoses, etc. The only thing I disconnected was the bracket that holds the solenoid assembly to the frame so that I could at least move that around a bit. It was by no means easy to get it done, but I made a point of being patient ;) and was successful. Now my issue - this didn't fix my problem. This all started two weeks ago when, after a 2 day track event and a 30 minute drive home afterwards with ZERO symptoms, the next day my 2014 Cayman S wouldn't start whatsoever. The starter cranked normally but the engine wasn't firing at all. I plugged in a Foxwell NT530 OBD unit and got a low fuel pressure code. Readings were in the 600-700 hPa range (if I read the Foxwell correctly). So, I assumed I had an HPFP issue (Note that I have had "micro hesitations" under low-gear moderate acceleration since I got the car in 2018, but have never noticed any acceleration issues at the track. So until this point I have lived with it and was hoping that the HPFP replacement would solve both issues.). However, the problem hasn't changed at all and the Foxwell, though now showing ~800 hPa, still is throwing a low fuel pressure code. I would greatly appreciate your thoughts on some question: Would there be an issue with air in the fuel system (I cranked the car a good long time and it never showed any signs of life)? If so, how does one bleed it? Could it be a relay(s)? If so, how may I debug that possibility? Could it be the LPFP in the fuel tank? I watched your excellent video on that topic and am a bit daunted by the thought of removing that ring around the top of the sending unit. But, before I tilt with that dragon, and before I drop several more hundred USD on the other fuel pump, will I be able to determine if it's bad by trying to turn it on and see the flow at the junction point in the back of the car you note in the other video? My concern is that fuel might flow but I wouldn't be able to tell if it was at a good pressure. Of course, any other thoughts/suggestions would be greatly appreciated. My goal of participating in a 12/7-8 track event is in grave danger at this point. The car has been up on jack stands for over a week... Extreme thanks for any feedback.

[@jeffrichardsoncardiy]

I'm not an expert on this subject, but what I do know is that the low pressure fuel pump is simply 'filling' the HPFP, so it can then increase the pressure and provide this to the engine. If it worked fine immediately afterwards I would think there is no air in the system. It will purge it very quickly. If you test the LPFP output at the join like I show in the fuel pump and sender video, this will give you a very good indication if it's working OK. You can see the rate that is pumped when the full 12V is applied in the video. Getting access to the top of the pump and disconnecting the fuel lines to test is pretty simple. If you do need to replace the LP pump, the tool to do so is now easily available. See link below. It's the same as the BMW pump. It takes a lot of force, and you will need a long breaker bar to remove. This is just the way it is, and the tank and fittings are designed to take it. www.aliexpress.com/item/1005006259802939.html?src=google&src=google&albch=shopping&acnt=631-313-3945&isdl=y&slnk=&plac=&mtctp=&albbt=Google_7_shopping&aff_platform=google&aff_short_key=UneMJZVf&&albagn=888888&&ds_e_adid=&ds_e_matchtype=&ds_e_device=c&ds_e_network=x&ds_e_product_group_id=&ds_e_product_id=en1005006259802939&ds_e_product_merchant_id=564517555&ds_e_product_country=AU&ds_e_product_language=en&ds_e_product_channel=online&ds_e_product_store_id=&ds_url_v=2&albcp=19821179470&albag=&isSmbAutoCall=false&needSmbHouyi=false&gad_source=1 The pressure you quote is pretty much zero. So it's going to be either the low or high pressure pump. Testing the low pressure pump first is the way to start the diagnosis. The micro hesitations are generally not going to be a fuel issues. Normally this is due to carbon build up in the intakes, as it's a GDI engine. See my video on walnut blasting of intakes for how to correct. kzbin.info/www/bejne/fqKzgYN8lN-cpJIsi=4bx7D-C8OXcjo9O4 kzbin.info/www/bejne/paHbgWp6odp4rtUsi=eDq2nY3JB0rcv2kg

[@tawaspt]

@@jeffrichardsoncardiy Thanks much for your reply! Very much appreciated. Well, I ran the LPFP directly from the battery and output the fuel from the under-car access point, per your video, into a .950L bottle. In about 2 seconds there were 5-7.5cm of fuel in the bottle. From my perspective, it seems to be working fine. So, new (remanufactured) HPFP, LPFP OK, car won't start and the OBD computer complains about low fuel pressure. Thoughts? (I will owe you a case of Fosters after this... ;) )

[@jeffrichardsoncardiy]

@@tawaspt You definitely don't owe a thing. I'm more than happy to help. The last test I'd do is to confirm the LPFP module is working OK. Have the fuel line disconnected like you did for the other test, then crank the car, so the fuel pump module is applying power to run the LP pump. If it flows normally, then I'd say it's the HPFP. Note that the flow will probably be less as it will adjust the output based on demand.

[@tawaspt]

@@jeffrichardsoncardiy Excellent idea. I will try this tomorrow morning (20:23 here presently) after I put all the "stuff" back together on top of the fuel tank. I understand the supply/demand concept that the DME will presumably manage. I'm just curious as to how that will look coming out of that pipe. Strong initial flow then less? Or? Is there a sensor downstream of the HPFP that could be bad? I just went through 2 HPFPs (OEM and remanufactured) and I would be surprised if both were bad (could Murphy's Law be that cruel?).

[@tawaspt]

​ @jeffrichardsoncardiy I forgot to ask. Is there such thing as an air purge/bleed process required? I have searched and found none.

[@GamePois0n]

Hello, could you make a video about how to remove and install the fuel vapor evaporator charcoal canister?

[@mechaniaclife]

Are you going to investigate the failure point of the pump? I just pulled mine after a failure and wondering if it can be rebuilt. Noticed a lot of oil on the top surface.

[@jeffrichardsoncardiy]

I'm not planning to. I had a good look at it an it seems you would need some specialist equipment and knowledge to rebuild. I'm all about rebuilding stuff if you can, but this looked beyond me.

[@mechaniaclife]

@@jeffrichardsoncardiy yea, I thought the same thing. Know any vendor that will buy back the core? I ended up purchasing a brand new one and was able to keep the old one.

[@jeffrichardsoncardiy]

@@mechaniaclife I haven't heard of anyone, but I've never looked. Another reason I didn't tear the one I had apart is because it was working perfectly, as is pretty much everything else in the car. There was a very high chance that it would be ruined once I was done, and trashing a perfectly good pump with the requirement to buy a new one to get the engine going again wasn't something I was willing to do. Are you in Australia? If so, and you can't find anyone to buy the pump and you plan to bin it, could I pay for the postage and have it so I could pull it apart and see what I could do?

[@mechaniaclife]

@@jeffrichardsoncardiy Thanks, Jeff. I am a US citizen. I will get in touch with you if I can't source a core exchange, it should go to you since you help all of us 981 owners out.

[@jeffrichardsoncardiy]

Thanks.

[@riyadhassan3803]

Hello, I have a 2007 Porsche Cayman. It has a problem. After running it for an hour or more, it starts to cut and stops completely, and this condition continues until it cools down, knowing that I changed the coils and spark plugs.

[@nicobekaert8729]

Hi Jeff , Nice series you're making . You are referring to thé maintenance manual , how did you get a hand on one ? Rgds Nico

[@jeffrichardsoncardiy]

Nico, link here for download www.planet-9.com/threads/workshop-manual.246427/

[@nicobekaert8729]

@@jeffrichardsoncardiy thanks ! Btw how is the oil catch can doing?

[@jeffrichardsoncardiy]

No issues with the catch can at this stage. The real test will be to remove the intake manifold after a good number of km to see the effect inside the intake ports, but that's a way off.

[@ameritooamando9845]

@jeffrichardsoncardiy . hi , how you can tell if the High pressure fuel pump has issues ? my car have same symptoms you mentioned but i don`t have codes. I have only on Live Data misfire in cylinder 3 and 5. please advice. thank you

[@jeffrichardsoncardiy]

The only real way is to check the fuel pressure via PIWIS or similar.

[@ameritooamando9845]

@@jeffrichardsoncardiy Thank you

[@ameritooamando9845]

I have question please. cayman s 987.2 cutting off in lower speed only ,, lower speed means 20 to 70 km . car has zero codes in diagnostic . Do you think PDK have issues ?

[@jeffrichardsoncardiy]

@@ameritooamando9845 It's extremely difficult to diagnose a problem like this without being there, looking at diagnostic readouts etc.

[@ameritooamando9845]

@@jeffrichardsoncardiy yeah i agree. thank you for the reply

[@joeyvanravesteijn9205]

Ive been fighting single cylinder misfires, no additional codes, fuel pressure is 105.000 hPa at idle. would that indicate a bad/going pump?

[@jeffrichardsoncardiy]

That sounds pretty good to me. Normally would see far lower than this if failing, and would normally have very long crank times on start as well. I'd be looking at intake carbon build up as a cause. This is a known issue and is rectified by cleaning, normally walnut blasting. I've made vids on all of this. kzbin.info/www/bejne/fqKzgYN8lN-cpJIsi=vp_veWj3E4n0IfLW kzbin.info/www/bejne/paHbgWp6odp4rtUsi=MfSEKcVsBd_m_T2q

[@joeyvanravesteijn9205]

@@jeffrichardsoncardiy thanks for the quick reply, the intake is pretty clean, checked with a bore cam, only has 23k km's on it. Recently did the IPD upgrade and had it mapped. No problems, only after about 3 hours of driving. Coils plugs solenoids, all replaced at this point.