924Board.org

[Judge]

Hello there, I bought a Porsche 924 from 1979 to fix it. Right now it is sleeping outside, and I'd like to get it running enough so that I can park it in my driveway.

The previous owner tried fixing it but couldn't get it running on its own, but it did run with an external fuel pump.
He did the injectors, hoses, thermostat, fuel filter, cooling pipe, and the ignition coil.
He replaced the fuel pump relay, but still, despite the engine cranking, the fuel pump would not start.

I replaced the fuses, and as a temporary solution, I've decided to run a wire with an amp from the battery to the fuel pump. I can hear the fuel pump turn on, and I tried cranking the engine but it wouldn't start.

I tried again, but before I could get inside and put the ignition on, the engine made a screeching sound, see this video:
https://imgur.com/a/6zxL6N6

From what I could guess, it seems the K-Jetronic has got air in the system, or it is flooding the engine.

I just wanna start the car and get it inside my garage, any ideas?

Additionally I'm in the South of France, apparently there are other French owners on the forum.

[Beartooth]

When I was getting my car going, I used a jumper wire in place of the relay until I was able to get a good relay. The two terminals that need to be connected are the one that's 90 degrees off from all the others, and the one opposite it. That screeching sound could be the the injectors, they make that kind of noise when they're flowing fuel. If it's making that noise as soon as fuel pressure is applied, than there's probably something wrong or badly misadjusted in the fuel injection.

I'd take the fuel distributor off (the square piece the injector lines connect to) and make sure the plunger moves freely. Be careful when you take it out: if it's not bound up, it can drop out, and it's a very finely machined piece that you don't want to damage. A fuel pressure gauge is something you'll probably need sooner or later; you'll want to check supply pressure, and then something called control pressure, which is another circuit to allow the system to supply more fuel for warm-up.

One other thing, there's a basic setting for the fuel distributor that may be out. Next to the fuel distributor is a hole with a stopper in it, and if you remove that, there's an allen screw. That fine-tunes the position of the arm that goes from the air flow plate to the fuel distributor; as airflow increases, the plate pushes the plunger on the fuel distributor, increasing fuel flow. Similarly, turning the screw clockwise increases fuel flow. It could be somebody turned that screw too far in, and that would cause fuel to flow even with the air flow plate at rest. Make sure the plunger and air flow plate and arm are free first, but if they are, then you might need to reset the adjustment. It's been a while, but I seem to remember what worked best was to back it out quite a bit, then (with the fuel pump running - and you shouldn't be hearing any screeching) turn it back clockwise to the point where you get that sound as soon as you move the plate, but no change in sound with the plate at rest. One last note on that screw: if you back it out too far, it'll come out. It's not the end of the world, but you'll probably have to take things apart to get to where you can thread it back in.

Before you dig too far into the fuel injection, you'll want to make sure you've got spark. I wouldn't monkey with the timing for now, but if you get stumped and think that may be off, there are ways to set that without the engine running or a timing light. Anyway, apologies if I'm talking below your level - I just want to make sure the bases are covered. It sounds to me like something badly out of whack with the fuel injection, and you never know what the previous owner might have monkeyed with. They're also very sensitive to contamination: I flushed all my fuel lines and circulated fuel through the system, but still chased gremlins for a while until all the varnish and gunk worked its way out.
_________________
1980 931 diamond in the rough

[Judge]

Thanks a lot that's very insightful.

It's actually my first project car so, lots of things in pratice that are different from theory

Some other guy suggested that the problems could all come down to a faulty ignition and bad grounds. I'll be checking those tomorrow, and I'll update.

Because obviously there's fuel, air, and probably compression, I might be missing sparks in the engine

[copeina]

x2 for the great description Beartooth. I'm in a similar spot and also in the process of learning about the CIS system. Much appreciated!

/Kris
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1978 924

[Judge]

[url]Good news! I have fuel pressure! Bad news, I have a fuel leak.[/url]

Well that's a new clue as to why it won't work.

[Judge]

I manage to fix the fuel leak and now the K-Jetronic injection makes a noise again, meaning it has fuel running it in, the question now is whether the fuel in it goes in the engine or now. Because if it does, then I have no spark. Any ideas of where I should check next?

[924RACR]

Well, it's easier to pull a spark plug wire and see if you have spark there, than to pull a fuel injector and look at that. So definitely check spark first.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Judge]

That's actually pretty smart. Do I need to pull the spark plug too or can I see anything with the spark plug wire?

[Fifty50Plus]

Pull the wire and stick in a spare spark plug. Have someone crank the engine while you ground the body of the spark plug (just touch it against a metal part of the engine). If you see a spark at the tip of the plug you are half way there!
_________________
1979 924 NA race car
1982 924 NA race car - Sold
1982 924 Turbo almost a PoS
1981 924 Turbo a real PoS, new engine
1982 924 Turbo nice body, blown engine
1972 911 E race car - going to Vintage
Various 944s to become IT-S race car

[Judge]

Update:
I've send staring fluid down the intake manifold while a friend cranked the engine, and nothing.
This leads me to believe that the engine has no sparks.
Time to double check the whole ignition system. Actually pretty happy about that because I don't have to rebuild a 1970 injection system.

[924RACR]

Yup, that's a quick easy answer there. Start at the coil, verify you have power there (should be 6V with ignition on, 12 while cranking), then go through the wiring for the pickup lead from the distributor to the ignition box, those often get flaky.

Don't count on the fuel system being fine just yet, though; at very least the injectors ought to be replaced, and the warm-up regulator is unlikely to be happy. Just hoping the fuel distributor is OK.
_________________
Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[Raize]

That screeching sound is K-jetronic flooding your engine.

It's a very distinctive noise.

Your engine will NEVER start under this condition and you will need to change your oil once you get the engine running as it will be heavily fuel contamined.

A leaky injector wouldn't cause this type of issue because fuel flow is only controlled at the metering head and should be ZERO with the engine off.

You can try turning the mixture screw at the metering head anticlockwise, this will hopefully solve the problem (it is the IDLE fuel flow setting). Otherwise, the plunger is stuck in the fuel distributor, you can try to free it off but watch out for it leaking. If it's properly corroded in then it's game over and you'll need a new metering head.

[Judge]

Hello thanks for the reply,
Yeah I figured that out, but I'll be doing a whole flush of the car before taking the road with it anyway.

I investigated more and tried to use starting fluide to see if there was spark, and there aren't.

A friend told me to check for the ignition control module, that apparently comes stock under the driver's headlight. Except I checked and there's nothing there. Worse, it seems the ignition coil has a wire going to the radiator's fan?

I'm getting more confused, it seems a past owner messed with the car's electricity system.

I might stop working on the car for now as I have exams, but once I'm finished, I'll tow it in my house and properly rewire everything as it should be.

In the meantime, anybody knows of a tutorial to fit brake disc on the rear wheels? Former owner told me the rear drum brakes were done, so I might as well just upgrade those.

[Raize]