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Jump wire went wrong
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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Fri Apr 26, 2024 7:31 am    Post subject: Reply with quote

Raize wrote:
mrborrie wrote:

Dumped some fuel directly in the hose for the fuel distributor


Don't do this. It won't work. The FD needs input of at least 4.5 bar pressure to function at all, it's not a carb.


Noted!

New pump came and installed it today. The pump still does not get power (like before I jumped the wire so I guess I need a new relay)

Powered the pump with a separate battery and tried starting, it goes round and does nothing beside burp every now and then some black smoke.

Pretty much back to where the car was before the incident
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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Mon May 27, 2024 6:38 pm    Post subject: Reply with quote

made video!

https://youtu.be/33TznoJO31U?si=rcGMySQtAP8VDqt8
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Raize  



Joined: 18 Sep 2013
Posts: 229
Location: Scotland

PostPosted: Tue May 28, 2024 5:20 am    Post subject: Reply with quote

Probably just too rich or too lean. Tried starting it with the accelerator pedal floored?
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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Thu May 30, 2024 9:25 pm    Post subject: Reply with quote

Raize wrote:
Probably just too rich or too lean. Tried starting it with the accelerator pedal floored?


Yep tried that on different levels of "push" not much difference.
Also tried start pilot in case of lean.. not much difference
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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Mon Jun 24, 2024 6:34 pm    Post subject: Reply with quote

Got some feedback on the YT video so its only fair i update you guys here too as part of the community

"Lifting the air intake was news to me, when controlling that i get flow. Based on the feedback here and on forums i bought a fuel pressure gauge. I get 3.5 bar on the injector line. I guess i need a stronger pump as Kjet needs more to work i understand."





Probably everyone knows this one but it made me giggle: https://grassrootsmotorsports.com/articles/using-scrap-wood-replace-porsche-924s-k-jet-inject/[/img]
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Beartooth  



Joined: 05 Apr 2022
Posts: 244
Location: Roberts, MT

PostPosted: Tue Jun 25, 2024 7:30 am    Post subject: Reply with quote

Hmmm, I've never tested fuel pressure output to the injectors - it's supply pressure (fuel coming into the fuel distributor) and control pressure (the line going to the warm-up regulator) that generally need attention. I'm not sure what the specified opening pressure of the injectors is, but the Haynes manual says 2.5 to 3.6 BAR. Regulated supply pressure should be higher (4.5 to 5.2), but you won't see that at the injector unless it's blocked. So make sure you're tapping into the supply line to check system pressure before you go any farther.
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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Wed Jun 26, 2024 9:32 pm    Post subject: Reply with quote

So its acts as a pressure regulator (FPR) not only a fuel block? Thats insightfull indeed and just in time. I drained the tank yesterday to put in the Kjet pump i did have but it needed fuel line adjustement to move forward.

Its a 10mm line on the filter as the issue but its all aftermarket with a 944 fuel tank strainer by the looks of it.

I think i have all the correct hoses in stock again so i might proces in putting in the more heavy pump.. But perhaps do the check on the main line, not sure how to get that off since the plastic of the airfilter was blocking my way.. Thats why i took an injector line assuming its not a FPR

Well at least i am having fun again and learning where before i was just angry at myself for messing up
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Beartooth  



Joined: 05 Apr 2022
Posts: 244
Location: Roberts, MT

PostPosted: Thu Jun 27, 2024 4:10 pm    Post subject: Reply with quote

Yup, we all have those moments we wish we could take back! The fuel pressure regulator is built into the fuel distributor, so you just T off the inlet line to test system pressure. It's a very different system from EFI, but generally simpler, so it's usually not bad once you understand how it works. The 944 strainer is a common addition in place of the in-tank pump, and it's arguably the way to go, especially if the in-tank pump has failed. I went a little different way, I adopted a sock filter in place of the in-tank pump on my 931, and it works fine. Several others here have retrofitted the 944 pre-filter, and I don't know of any negative reports on that. I suspect it might be an issue when the tank is very low, or or may not prime if it's run out of gas, but the original in-tank pump is just too expensive to be worth replacing if it fails. As long as the main fuel pump is rated for CIS pressures, I wouldn't worry about it. Too big a fuel pump is almost as bad as too small: too much of a strain on the wiring and charging system.
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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Mon Jul 01, 2024 4:40 am    Post subject: Reply with quote

5 bar verified and that diagnose came with a free new thing to fix 😂
Does not look Porsche specific so perhaps I can find one , tips?

So fuel seems okay
Spark seems okay too (tried a Volvo 940 coil too since I had one around, same result)
Timing seems the next logical step I guess

Symptoms now are the car turns around and nothing, after around 10 seconds the car starts sputtering every 5 seconds or so.

I also noticed that the starter is making wierd noises now, could that be a thing?

In other word what is my next step looking at what I have now?






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mrborrie  



Joined: 09 Jun 2021
Posts: 29
Location: Netherlands

PostPosted: Mon Sep 23, 2024 2:36 am    Post subject: Reply with quote

Car is running again!!!
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