My wife uses our 74 164 as a daily driver.I usually keep it tuned up ie.points,plugs ,basic maintenance etc. Lately shes been complaining about hard starts after the car has been run and warmed up or even after it has sat for a couple hours. Also she claims it sometimes hesitates badly with loss of power. Anybody experienced these symptoms on their 164's? Cold start injector? What's the easiest way to test? Leaky injectors...how can I tell? Vacuum leak...is this just a matter of checking all the hoses? Someone suggested" disconnecting the thermal time switch behind the exhaust manifold " for a similar problem on a 75 164. What does this do? Any help appreciated. These are great cars.

The thermal timer switch closes (New spec) when water temp is below 90 F, I believe, which opens the cold start injector during starter cranking.
I my experience, older, well run-in b20's (probably b30's also), don't need this extra gas, and seem to be hard to start when warm, possibly flooded.
Could be of 2 reason I can think of now.
1. Engine cools quickly enough to close switch, but even mildly warm engine is easy to start without cold start injection.
2. Switch degrades in performance, staying closed longer and at higher temperatures.
I bypassed my TTS with a dash switch, which I only had to use in the coldest weather.

They are great cars.
I would do a fuel system pressure check. See that it has sufficient pressure when running, and then confirm that it maintains system pressure when shut off. The pressure decreases to a lower value and then creeps down slowly from there over several hours to prevent the fuel boiling in the injectors and fuel rail. If you have no rest pressure, then the vapourous fuel causes the hard hot start, and rough running until it is purged through the pressure regulator. I may also be a good idea to replace the insulator washers and neoprene seals on the injectors and injector holders, and they insulate the injectors from engine heat. To test for leaky injectors, simply leave them out of the holders during the seal replacement, and power up the fuel pump for a moment. Watch the injector tips for any dribbles. Slightly wet with fuel is OK, but drops are not. The idle air bypass hoses are a source of trouble. The factory didn't use clamps on them, so when they get old and brittle, they will pass a bit of air. If they are still pliable, put some clamps on them.

Thanks for the info. What kind of pressure reading should I have when running? Is it simply a matter of turning the bolt down on the pressure regulator untill the pressure increases? If I dont get an increase is it possible the regulator is shot? So the pressure should gradually decrease over a period of say two hours and if decreases quicker then the injectors are leaking or there is a problem with the regulator?

The pressure should be 28 psi. The regulator is a bypass type that opens
and allows gas back to the tank whenever it goes over the set pressure.
Loosen the locknut and turn the bolt to adjust pressure. It is possible the
regulator doesn't seal tightly or that you have a leakdown somewhere else if
the pressure goes down too fast with the pump not running.
--
George Downs, The "original" Walrus3, Bartlesville, Oklahoma

I think the rest pressure should be around 15-20 psi. and fall from there. As George says 28 psi is the correct running pressure, and as long as it is that value plus or minus 2 psi, the problem is elsewhere. In the discharge side of the fuel pump there is a small check valve that holds pressure against the regulator. Figure at least two hours to zero pressure. (these are all approximates - my D-jet manual is "in storage")

Thanks for the info guys. I'll rig up a pressure gauge and test out the pressure.It seems to me that these cars have all the luxury of a modern car without the price tag. Great highway cruisers....and good handling,thePO put on IPD sway bars and its rock solid when passing. Up here in Winnipeg it can get -40 and these cars have the best heaters I've ever come across.