Hot Start Issue 1987 911

[djsioukas]

I have had a problem with my car lately. Car starts fine. I'll arrive at my destination with the car now warm / hot. I'll go back in the car and it turns over super strong but no start. Once the car cools, it then starts again. Super frustrating. I've changed the coil. I've changed the DME relay. The starter is also new. Any ideas?

[jussumguy]

Mine was doing that. There’s a little o ring in the top of the fuel distributor. I think it is the regulator. The inner o ring is probably beat up. Easy fix

[911TerryT]

fuel regulator was my hot start issue. I just replaced it as it was original 78 equipment.

[jussumguy]

Where did you find the oring? I just got an assortment from harbor freight! It wasn’t exactly the right one but it sure fixed the problem instantly. I tried to get the correct one from pelican but it isn’t listed anywhere

[wazzz]

Originally Posted by djsioukas

I have had a problem with my car lately. Car starts fine. I'll arrive at my destination with the car now warm / hot. I'll go back in the car and it turns over super strong but no start. Once the car cools, it then starts again. Super frustrating. I've changed the coil. I've changed the DME relay. The starter is also new. Any ideas?

Since car runs fine once started and keeps running fine when warm, but does not start anymore when warm, that makes me think of a weak ref sensor that would go bad when hot.
Once car is started, ref sensor is no longer required provided the other sensor (engine speed sensor) is good. How long have your sensors been running? May be time for a change. Get two Bosch 0 261 210 002. They are cheap quality replacements.

Or maybe just unplug them at vertical ramp on left hand side of engine and check and clean their contacts.

You may also want to check the CHT sensor, white connector on vertical ramp.

[76FJ55]

Fuel damper and regulator diaphragms are prone to leaking with age as well. when this occurs fuel bleeds through the diaphragm nd into the vacuum system flooding the intake with fuel vapors making it hard to start. cold engines usually all the fuel has evaporated and left the intake, plus cold engines don't mind the extra fuel as much so it isn't a problem. next time you have to start the engine hot try pulling the fuel pump fuse and then start the car. it may start then die shortly after. once this has happened it should have burned the excess fuel off, so reinstall the fuse and try again. if this works you will need to determine which diaphragm is leaking and replace it.

[Mr. Merk]

Originally Posted by 76FJ55

Fuel damper and regulator diaphragms are prone to leaking with age as well. when this occurs fuel bleeds through the diaphragm nd into the vacuum system flooding the intake with fuel vapors making it hard to start.

Easy way to check this is pull the vacuum hose off of the two fuel diaphragms and see if there is fuel in the hose (there should not be!)

Originally Posted by wazzz

You may also want to check the CHT sensor, white connector on vertical ramp.

This was my first thought. Mine failed on a road trip, so we bypassed the sensor and grounded the signal wire directly to the intake manifold ground point. This got me home but made it almost impossible to cold start the next day. I replaced both crank sensors and the CHT (cylinder head temp) sensor