so I just took my 87 GXL to mazda because it has a problem starting at warm temps (specifically when I let it sit for 30 minutes after running it for a good amount of time). They say that I need new apex seals when one of my buddies said it was a temp sensor. which one is right? I really need help because I need the car
it runs perfectly fine when started. and when it refuses to start it cranks and I have to pump the gas to start it.

 

Compression test it. Don't trust Mazda until you find out yourself. I would also always recommend installing a temp gauge to always get accurate readings.

 

Could be something as simple as injectors bleeding into engine after turning off and causing a flooded situation. Perform a compression check and if it looks good have your injectors rebuilt.

Good luck!
-M

 

To troubleshoot this remotely sight unseen, we're going to need more details.... So you say it runs fine once started, and the no start issue only occurs when the engine has sat for about 30 minutes after running at operating temperature. When you say "runs fine" does that mean performance under load is good from idle up to redline - i.e., you hit the go pedal and she moves off without hesitation? What about cold starts? Does the engine fire right up if it was overnight cold, or say at least several hours after it was last run?

Do you know how many miles are on the motor? I wouldn't trust a word the Mazda dealer told you if they said "needs apex seals/replace engine" without first doing a compression test and showing you results.

 

So I did a poor mans compression Compression test and it sounded fine (the rhythmic sst, sst, sst, sst) So as of right now it dossn't sound like compression. My car has 112k miles, doing a thorough test on Sunday.

 

Well, that test really tells you whether or not it has compression at all. But it isn't an indicator of how much compression the engine has. A new engine and a worn engine will both make rhythmic sst, sst, sst noises, but a blown engine won't. Buying a compression tester is the most thorough way to get a firm number for compression.

The best thing to do would be to test as per this guide: Link to Racing Beat

One thing that isn't mentioned is you should pull your EGI fuse, so your injectors don't fire (to avoid flooding). Make sure to perform the test warm. Report back with some results, and it's easier to go from there.

 

yes, id go even to say its retained most of its power throughout its 30 year history. Im able to pull her from a dead stop to 60 in about the same time as a factory spec fc (7.9 seconds but I think it might be faster than that). I was able to max her out on the highway at about 122mph this is about 10 less than factory. It has 112k miles. Cold starts are never an issue.

 

The after sitting 30 min part makes me think injectors as well. Don't know about the S4 but on the S5 if you floor the accelerator while cranking it disables the fuel injectors. I had to start my car this way if it sat for a while but was still warm. After I got the injectors cleaned it went away. You could try this to diagnose it. https://www.mazdatrix.com/c-bleed.htm

 

So one of my friends who is helping me suggested this as well because I would take the fuse for the injectors out and crank it a couple of times and put it back in and it would run. Compression test came back as an 8 or 120 psi. we even replaced the starter to see if it was the calanoid but it didn't change anything.

 

^Given this comment and prior comments on how the engine runs, most likely its flooding due to leaky injectors. Doing a compression test won't hurt, but poor compression is not your problem now. Pull the injectors and ship them out for the full cleaning/flush/flow test service or buy brand new OEM injectors and pop them back in. I've had good results using these guys for injector servicing: https://injector-rehab.com/shop/home.php

While you're at it, you probably should replace the fuel filter, and replace all the old vacuum hoses with silicone hoses, and replace all the old fuel lines with new EFI fuel line hose.

 

so I've changed the injectors and I'm still having the problem.....