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Fuel Injection Problem 76 911 S


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First time posting... so Hi! to all.

So here is my problem.

Relativley new car to me , bought it a few months ago.

Ran but it lacked power and took a while to warm up.

I pulled the fuel distributor and injectors to clean then. the spray pattern of the injectors looked bad.

Cleaned everything up, put it back on my car and it won't start.

pull the injector when cranking- no fuel

crack the injectors at the distibutor- no fuel

Replaced the distibutor with a spare i had- getting good fuel ,starts up then floods.

Pull the injector when cranking- nonstop fuel

replace injectors because i thought they were leaking.

Same problem....

seems like too much fuel pressure.

Any help would be great , not sure where to go from here.


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Funny thing, right after I posted I got the car running. It had a small miss but it started fine and was running. It starts everytime no problem

Had my son wash the car. I started the car was going to move it and it dies.

Now it won't again this time no fuel

i'll check the cold start and see what happens

Any other suggestions would be great


Edited by plob
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playing with the CIS can lead to flooding engines and exploding Manifolds. Floddeed engines don´t start and craked manifoldes make a hard start.

Right now the first thing to check would be if the fuelpumps runs correct.The fuelpump only runs while the starter turns and/or when the choke plate on the CIS regulator is liftet off.

Now a funny thing that can happen is if someone removed the manifold unit with the CIS and didn´t mark the wires you can swap the fuel contact wire with the cold start injector wire. The engine will start but run very rich and has a lousy performance.

Right now my forst check would be if the manifodld doesn´t have cracks or an air leak is somwhere else. The 6 Manifold runners can come loose on the head and the flanges do warp over the years and the plastic inserts for the injectors can leak as well. This will explain some from the poor performance.

Now finding and fixing CIS Problems start with messuring the Fuelsystempressure and the Working pressure drop relatet to the WUR timing.

The CIS messuring unit have a main plunger inside wich has a rubber seal who can swell over the time ( deppending on the fuel) and if water is in the fuelsystem the plunger can rust and stick. There is a reseal set wich is aviable at Bosch or Mercedes Benz.

On he old rennlist section is a user page with the complete CIS papers and a trouble shoot tree.


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