Engine back in - won't start.
 

Reinstalled my engine in 84 911 last night and it won't start.

Car has not been started in about 10 months.

Need some advice on how to proceed:

1) I have seen a lot of posts about injectors getting stuck. We "tapped" two of the injectors while trying to start the car multiple times. Do they all need to be "unstuck" or if we get a couple loose should the car at least start to run on a few cylinders?

2) We have spark (tested with spare spark plug) and fuel movement (as we had an open fuel line which we missed and attached after discovering the leak.)

3) We pulled off one of the connectors on an injector and don't get any voltage when cranking the engine. Should we?

4) Other posts indicate this could be a sensor problem. How can I test the various sensors to see if they are properly hooked up.

Any advice appreciated as everything is back together after a LONG time and would really like to get this resolved soon!

jcsjcs

check your DME relay

Is it likely that the DME relay could go bad after a period of non-use?

Will check - but want to understand.

Mine wouldn't start after an install, and it turned out that I had not reconnected the bundle of Brown ground wires on the left side of the engine. Are you sure these are connected?

Of all the sensors that could cause a complete no start, the 2 flywheel sensors are the main culprits. Not hooked up, the DME would not even know the engine was turning over, so would not fire the injectors.

yes...they can go bad without the slightest provocation.

All the other suggestions are also very good. I would first check the ground batch at intake #1, then the DME relay, then the 2 sensors. Start with the easy stuff first.

DME relay must be working or the fuel pump would not work.
There is spark, so I would think the speed and reference sensors are also working.
You should get voltage to the injectors when cranking. Have you made sure the connector by the shock tower is snug. Check for voltage there. This branches out to all the injectors.
Otherwise it might be the DME itself.

Reference sensors reversed?

Try tapping the injectors with a wodden screwdriver handle while and assistant is cranking. They are notorious for getting stuck closed when sitting more than 3 month. And sure check the the sensors (reference and speed) are not reversed.

Ingo

Ditto above ^^^ - check all cables.
The speed and reference sensors are easy to reverse. I Added coloured tape to both parts of one sensor cable.
The sensors can be tested for resistance, values in bentley manual.

AFAIK the injectors are earth switched? and cannot measure this with a volt meter. Think an oscilloscope shows square wave, with dip corresponding to low voltage when injector is open.

Does yours have immobilser? My 3.2 would not start after 9 month long rebuild. Tried all of the above and more, as I had not spark or fuel. My duaghter asked about security thing, so I refitted the immobiliser "key". Started first turn. Doh!!!!

Since you have spark this is not an immobilizer issue. On the 3.2 it simply would have cut power. You can confirm whether it is sensors (reversed or not good) by spraying starter fluid into the intake.

The logic is that once you have spark it could still be bad timing (reference sensor marginal). Else your problem is either stuck injectors (likely) or a damaged DME (fuel injector output stage).

Ingo

I first read this thread as ...................Engine In Back - won't start..:D

You have spark, and you have fuel, right?

I am at a loss, sorry.

He wanted to say: "We have fuel pressure" He had a leak at one of the fuel lines and deducted correctly that the fuel pump was running during cranking.

Cool.

Still looking for a faulty connection to a sensor though, right?

This happened to me once and I went into great depth looking for the problem; forgetting one of the first things auto repair had taught me... Look for the simple and obvious things first. I know you can tend to get frustrated and then all of a sudden you find yourself knee deep in Porsche.
I had replaced a clutch and when I tried to start the engine, it would crank but not fire. I searched high and low; DME, ECU, fuel pressure, alarm system, coil, sensors and after all that it turned out to be a wire harness had become unplugged from underneath the dash, just left of the steering column. I discover the loose connection as I was about to replace the ignition switch.
Look for the obvious.
Hope this helps.

Thanks for the all the replies - this thread took off when I wasn't looking. Planning to spend a few hours this weekend and will report back.

Great suggestions!

You had the engine out... what did you do to it while it was out?

Other gotcha items... other than sensor issues... did you plug in the 4-pin connector that rests on the little shelf behind the engine? Distributor in correctly? The aforementioned ground wires, including the tranny ground? The 12-pin (or is it 14?) wiring harness connector in the engine compartment is in securely, and no wires have come out of the connector block? The big ECU connector is snug into the ECU?

JB

That was it! Thanks for the tip.

The actual overall problem was the fact that we had 3 oil hoses BELOW the engine and 3 electrical connections ABOVE the engine after we reinserted the engine. Probably a novice mistake - which we will not make again.

Car runs GREAT after 11 months off the road.

Shifting is remarkably great!

Thanks for the help.

Another post coming to thank the entire community.