97 Mazda 626 2.0L Hot Start Problem
 

Hot Start Problem

Car: 1997 Mazda 626 LX 2.0L – 148,000 miles

I have been trying to hunt down this Hot Start Problem for some time and I can’t seem to locate the source :confused:, so I am turning to some of you experts here. When the engine is hot, the car usually takes about 6 seconds to start with me holding the key in the start position, but if the engine is cold the car starts up right away. I have been going by the rule that the problem could either be Air, Fuel or Spark and have replaced the following parts:
1. Spark Plugs
2. Air Filter
3. Fuel Filter
4. Fuel Pump
5. Battery
6. Ignition Coil
Has anyone else had this problem or has anyone heard of a fix? Also, my car does have a distributor that is installed at the Head and Valve Cover.
Thank you ahead of time for your help.

When my car is hot, it doesn't start on first try either, did it a couple times today. I have double the coil voltage and really good plugs! I guess maybe, turn the key to "on" position for about 2-3 secs before actually turning over the engine?
I also have synthetic oil if it makes any difference?
It's almost like when I let of the key sometimes, it springs back too far.

Sometimes oil gets into the distributor, but that causes misfires not hot start problems.
Make sure the intake air temperature sensor is clean, look for vacuum leaks.

In carbureted engines you sometimes get vapor lock. I can imagine something similar happening in the fuel rail. If there is vapor in the fuel rail it could make life difficult for the pressure regulator. Once the vapors are pushed passed the regulator things should be alright. That is just theory. May someone with real knowledge chyme in.
It helps if the EGR valve closes completely and the idle air control valve is clean and functional.
Check the EGR Boost sensor and the vacuum line that goes down behind the intake manifold. Pull it off and poke into the nipple with a strong wire. It gets clogged. Here I assume that it is the same as with the Protege.
Turn the AC off prior to starting.

Thanks for the responses

tanprotege:
I currently have the throttle body off and in the process of getting the IAC off the throttle body, when I get passed this I will perform a funtionality test of the IAC (using a freezer and blow dryer). If the IAC is fine I will then check for vacuum leaks. I tested the EGR valve about 2 months ago when I had the Intake Manifold off, also I cleaned the vacuum Port on the back of the Intake Manifold (that was clogged big time). Do you think the Pressure Regulator might be a problem? Boost sensor? Someone in another mentioned the possibility of fuel vaporizing in the fuel rail. Seems very logical in relation to the type of problem I am having.

I have some updates:

- Turns out the IAC failed the freezer and blow dryer test.
- I picked up a throttle body and IAC from an 02, and everything looks like it will fit up fine. Is there any reason why this won't work?

Great job! and thanks for the update!
I don't know for sure if there were changes between the model years that would make the TBs and IAC incompatible. Go to RockAuto and check the order numbers between the different model years. If the parts number are the same you are A-o.k. If they are different you may have issues.
Vapor in the fuel rail should not make much of a trouble. Once the fuel pressure goes up the regulator will open the recirculation line and the vapor ends up in the tank. However: vapor can be compressed, fluid do not. That means the regulator will be late in opening, but it still will open. Maybe that is why most engines need an extra second to start up when hot.
If the membrane in the pressure regulator is damaged you have a bunch of other issues. You tend to get fuel into the intake manifold through the vacuum line. You get a rich condition and flooded engines. That is probably the most common failure mode for the FPR.