Delayed start when warm (sometimes only)

[Skip1]

So, having brought the car back out of hibernation ('84 Targa ROW) a week ago or so, I've noticed periodically that when I make a short stop (about 10 mins or so) the car periodically takes a fair number of engine rotations before starting. It does always start however. The car runs very well, and normally instantly starts. I replaced the reference and speed sensors about a month and a half ago, and have confirmed their resistance when the engine is both warm and cold, and they seem fine. I wonder if there could be a fuel delay or fuel vacuum issue whereby the pressure isn't held in the line sometimes?

Any ideas?

Thanks.

[blucille]

search fuel pump check valve and see if it matches your symptoms. Could also be the fuel accumulator.

[kodioneill]

1984 911's had motronics for fuel and spark I don't believe they had a accumulator. As for the problem it could be one of many things that you have to rule out one at a time. Could be sensors (cht), fuel pressures, ignition, valve / tune up issues, afm, ect...

[Skip1]

OK, thanks, guess it's back to basics again - ah the 911... :-)

Will add the check valve to my testing as well.

Thanks

[john walker's workshop]

did you remove the bracket when the sensors were replaced or leave it attached? clearance is important. old or new style head temp sensor? recent dme relay? recent fuel filter? ignition distributor not internally self destructing?

[Skip1]

I had to remove it as the sensor screws were rusted and seized in place.

New style temp sensor replaced about two months ago, same with fuel filter, dmd relay, and distributor / rotor / plugs / wires and complete tune up and valve clearance adjustment.

How can I ensure the proper gap on reference sensor without splitting the engine from the transmission / engine removal?

[ejp]

I had the same issue in my 3.2. Long shot, but check the intake header gaskets. My problem was resolved when these were replaced.