Got the engine started but not running

[bwsimmons@shaw.]

1977 Porsce 911S 2.7 I am finally able to get the engine started but I have to prime it by lifting the air control flapper for about 10 - 20 sec. The engine will then start and will run if I keep the throttle depressed and hold the tach about 4000. When I release the throttle the engine quits and won't restart without being primed again. I repaired the safety switch on the flapper so that it is open in the raised position and closed in the at rest position. I don't know where to look next. Any suggestions greatly appreciated.

[cstreit]

Don't know the history of your motor, but I'd first check the timing... Then check the control pressures and see where you are at. Report back from there?

Is this a new build, old engine, etc?

[bwsimmons@shaw.]

Thanks for the reply Chris. This is not a rebuild. I had the engine out to replace the clutch and to clean it up. I replaced all the seals and gaskets I could get at. I had the tensioners out but I wired the chains before removal and didn't move the cams while the tensioners were out. I didn't remove the distributor either for the same reason, I didn't want to affect the timing. What do you mean by control pressures? I checked the volume of flow from the fuel pump but I didn't check the pressure. Is this what you mean?
thanks, Barry

[Walt Fricke]

BW

You test CIS system and control pressures by plumbing a pressure gauge, with a three way valve, into the fuel line connecting the fuel distributor and the WUR. For general CIS engine ailments you want to do this to check that things are as they are supposed to be.

But in your case those things would be pretty far down my list. Somehow you either dislodged something or reattached something incorrectly. For instance, if you switched the safety switch plug with the cold start valve plug (sounds like you didn't do this, though my suspicions are raised because you had some kind of problem with this and disconnecting the interlock will allow the engine to start and run fine, just with less safety), but it also sounds like maybe the CSV isn't squirting because you are "priming" with the main system to get it to start).

Or maybe you dislodged or tore the rubber boot connecting the right and left sides of the intake system. Old boots can get brittle. If you find a tear, duct tape will work for a long time until you find a replacement. That boot can get jostled when you install the engine.

Anyway, I'd go over everything I did, and look at how everything got hooked back up.

Since it won't idle, I gather, it will be tough to do the normal check for leaks: put a hose over a propane torch, turn on the propane a bit, and stick the hose by various places to see if intake leaks allow propane to be sucked in, raising the idle speed. But maybe that would work at 4 grand too?

Then, just for grins I'd at least check the static spark timing. And inspect the points. I'd also check cam timing, which is not hard, but then I have the holder and a dial indicator and you may not.

Keep at it - has to be something biggish, and thus it should be findable and fixable.

Walt

[cstreit]

I mentioned CIS control pressures because I assumed he checked all the connections and spark. However ifyou haven't, obviously, start there.

You need to verify fuel and spark of course. Fuel is easy, pull an injector and press the air-plate. See if you get a good strong fuel spray. If that works, then pull a plug wire and put a spark plug on it. Put the plug on the block and have someone crank the engine and make sure you're getting a nice spark. If you are, the you need to check spark timing. Use your timing light for that.

If all of those check out, since the next thing you changed was the tensioners, I'd verify your cam timing.

[black993]

I'd go with the ignition timing first.
Maybe cam timing slipped a touch too!
Good luck, let us know
Art

[bwsimmons@shaw.]

Thanks guys! I have a lot of leads to check now. It is really tough trying to check these things when you are working alone. I guess I am going to have to find another body to give me some help.