I have been having a hard time starting my '94 lately. It starts good when it's cold, but it is almost impossible to start when it is at normal temp and it is shut down for a short amount of time. I changed the plugs and checked for anything major. The motor is pretty fresh and stock, with only reliability mods.
I get no codes, but there are a couple of solonoids and sensors that I wanted to check out under the extention manifold. I also wanted to replace all of the vacuum lines, which are mostly rock hard.
When dissasembling the intake pipes, throttle body, and manifold I have noticed a lot of oil residue inside. Is this normal? I just wondered if I should look into this.
Any info. on any of these issues is greatly appreciated. Thanks for your time.

Garrett

 

A little oil residue in the intake is normal.

If you are getting puddles of it at the lower point of the intercooler, then maybe it's too much and your turbos might be going out.

I would look into the hot starting problem - is the engine eating coolant? Any chance the coolant seals are leaking into the combustion chamber?

Dave

 

i had a similar problem, but I got a check engine light for the coolant temp sensor. but, out of the 15 times that my car had starting trouble, the light only came on once. so definately check or replace your coolant temp sensor. if it's faulty, the ECU won't know what temp the engine is, and will think it's cold and add too much fuel.

 

Given the information you provided so far, I would take a look at the Fuel Pressure Regulator and its associated solenoid (labeled PRC, Pressure Regulator Control). Its used for hot starts to help control vapor lock.

Here's a diagram which will hopefully help you on your troubleshooting:

http://www.fd3s.net/vacuum_hose_diagram2.jpg

 

Thanks very much for the information. As far as the oil goes, it doesn't seem to be a lot. I'll see if I can get any out of the intercooler. Coolant level hasen't really changed. No oil in coolant or coolant in oil.
I have an old Honda commuter thad had a bad coolant temp. sensor. It had the same symptoms as the Mazda. When researching manuals I couldn't find any info. that pointed to that sensor so I just blew it off. I will definately remove it, test it, or just replace it.
I will also check the Fuel Pressure Regulator and PRC. Thanks for the diagram.

Thank you again for all of your time. This really helps.

Garrett