Help, dont start when`s hot!

[Lubo_car]

Hi, I`m Lubo, from Bulgaria ( Eastern Europe). I`m from Bulgarian Mazda Owners Club. I have RX-7 FC TII 1988 182hp. I have problem with my car and want to asking you for this.
Before one mounth I have problem with loosing the water. Problem was gasket on intake manifold. I replese this gasket ( very hard work, because I remove motor for this operation). After change everything was ok. But now, one week after this, I have other problem. When engine is cold, was no problem to start. But when I drive some km., and stop, after that I cant start the engine. If car stay half of hour or more, afret that is no problem to start. If I try to start the car, when somebody push me at back, car start without problem.
I change battery ( new with 72ah), new spark plugs ( Ngk bur7eqP and bur9eqP â€" new), new water cap with gasket ( and new antifreeze mixture), and some other things, but with no result. This problem`s from 4-5 days and I cant understaend wats the problem. I check electrical, and don’t found something in problem.
I cant undestaend, why car start without problem when somebody push me at back, and when is cold, and when is hot â€" engine don’t start ( starter work without problem).
Is that possible problem to be fuel pump, or injector ( someone from injector not to stop when I stop the engine, and make benzin in spark plugs?), or may be ecu?
Please someone to help if know what can be the problem. Now I driving my car from two years, and to this moment I repair everything on my car, but now I don’t know whats the problem.
Other, I wait new parts for my project â€" full exhaust system 80mm., re-amemiya ecu, bov apexi, cold air intake and other, and cant making anything when my engine is with this problem.
Beforehand thanks, wait your answer friends, and excuse me for my English!

[Carl]

Hi Lubo,
Welcome to the club.
I think that the engine must have low compression,that would mean that the engine needs to be rebuilt.
What you have described points very strongly to that.The overheating could have contributed to it.
Have you checked the compression?
Regards
Carl

[grinder]

first thing before going mad on it - get it compression tested

its not looking good though

Stu

[gsb876]

Sounds like bad/low compression sorry to say dude

[Lubo_car]

Thanks guis for attention. Now i write what i found today.
First and importand`s my compression. Unfortunately she`s not good. Compresion on first rotor`s 2,8, and on second`s 5,2. I know that maxumim compresion is 6, and minimum 3. Maximum different between two rotors`s 1,5.
I checked compresion when my motor`s to normal operation temperature, after that i stop the engine. I wait 10 minutes. After that i disconnect CAS (Crank Angle Sensor) connectors and check the compression.
I want to say, that from 1,5 year only myself ( with one my friend) repair anything to my car. Before some years we repair other rx-7. I have original manual for my model. I repair anything to my car with this manual.
I cant undaerstend something. I have my car from 1,5 year. To this moment i have absolutely no problem with starting when`s hot. Dinamics and running on car, now and before this period ( 1,5 year) is WITHOUT any different. My car`s with better time at 1,4 mile from over 20 cars with 150++hp ( here in Bulgaria), better from Civic VTI 160+ tuned , from most VW TDI(131hp + chip tunning 167hp) models and more, and more cars. Finaly my car running very well. My time on 1/4 mile is 15,7.
My question`s - is that possible, with absolutely no differents in dinamics for this 1,5 year, my car to be faster than this cars, and to be with 2,8 compression ot first rotor ?!?!?!?!
Some from you frends says for vacum leak, starter problem, comutators. I garanted that vacums are 100% ok. Starter running, I thing, without problem, without different in noise, when`s not or cold.
I have new timing belts, new spark plugs, new battery.....
I see that you write for commutators. Where`s this commutators in my car, becouse i thing that i have`t this? And why my car starts without problem when someone push me at back, every time. If is elektrical problem, i thing that car will not start, doesn`t matter when stay or move?!
I won`t believe that my motor`s for rebuild. . Ok if it`s for rebuild, why is absolutely no differentin dinamics for this 1,5 year that i drive the car???
I looking for other possible problem, without problem with compression. Is that possible to be atmosferic presure sensor to make this problem with hot starting. Or may be injectors or connectors on injectors. Other - fuel injection pressure regulator. Fuel pump, do you thing that make this problem? Ot ECU problem. But i cant understaend why before problem with intake gasket ( for this replace on this gasket i remove the engine) i have no problem with hot starting, and now i have this problem. If is compression why before this i have not problem with hot starting, and running on my car is same?
I make something - i move out two fuses ( egi comp and other, to this fuse, i forgote the name) and try to start the engine with full gas on the pedal. This for 5-6 seconds. After that i wait 20 seconds and make this again. After i move on this two fuses, and try to start. Again motor dont start. I make this becouse i wanted to check for injektors problem.
Please if someone from you know somethig for my problem to help me, becouse i won`t to open my motor. I opened and repair only one 12A engine before 3 years, but wont to open my motor becouse i`m not 100% sure that will make everything write. Here in my country is impossible someone else to repair this motor.
Again beforehand thanks, and thanks for attention.

Lubo ( Bulgarian Mazda owners club) !

[grinder]

if you think that it SHOULD be ok - check for leaking injectors

you sometimes find that when you shut the engine off - it leaks a small amount of fuel into the car - hence flooding it

the push start will probably force all the excess fuel out and then it starts

thing to try

1 - start the car and leave it to run for 10 mins
2 - shut the car off
3 - leave for 10 mins
4 - pull the EGI fuse out
5 - remove spark plugs
6 - crank engine whilst someone looks in the engine bay
7 - is loads of fuel being forced out of the spark plug holes ??

if this is the case - then it might be leaking injectors

OR

1 - fit a fuel cut off switch ( so that you can turn off the 12v feed to the fuel pump )
2 - go for a drive
3 - park up
4 - turn off the fuel
5 - when the engine sounds like its about to stall - turn the car off
6 - wait a few mins
7 - turn fuel pump back on
8 - try and start the car

its 2 things to check at least

Stu

oohhh hang on - 1 more thing to check

1 - run the car
2 - turn the car off
3 - try and start it
4 - by rights - it wont start
5 - pull the spark plugs
6 - are they covered in fuel ??

Thats about it for now

Stu

[Grizzly]

If your Compression is 2.8 on the front and 5.2 on the rear you need a Rebuild.

You should have six figures for a Compression test but even if you spin it over on a Piston engine type Compression tester you should get alot higher than 5 bar.

I would say you may have a Carbon problem if your Compression is low where the Fuel is not burning cleanly and leaving Carbon deposits in the Seal grooves, this will also cause low Compression when the engine is not Turning and will get worse untill a seal will stick.

Do you have problems starting from cold? does it use any Coolant at all?

[Lubo_car]

Thanks for answer. Absolutely no problems with cold starting. At winter i use antifreez mixture 60%/40%, at other time - water. Now no cooland loose.
Are you sure that problem`s low compresion? Is that possible to be - injector/connector problem or wrong fuel mixture, or fuel pump, or any something else?!
When i remove spark plugs(new bur7eqP / bur9eqP) ot first and second rotor, they`re absolutely SAME - covered in dark, and with gas.

Is that possible this 2,8 compresion to be for wrong fuel mixture, bad injectors/connectors, fuel pump or something else?!

[Grizzly]

You need to get the Compresion checked properly then if it comes back lower than 5 it needs a rebuid with out a doubt.

The thing is you should have 6 figures (one for each rotor bath) when you look at the results you want a figure thats above 5bar on each bath and whats more important is the amount of diffrence between all six figures, you don\'t want more than about .4 of a bar diffrence.

Unfortunatly Low Compresion is something that means engine rebuild, it is things like Apex seal Springs loosing there shape and not pushing the Seals hard enough against the Housing.

[Lubo_car]

Thanks but i have`t other compression tester different from this for normal piston engine. In my country`s impossible to found original tester for FC. I write how i checked compression ( by my manual) and it be - 2,8/5,2. Is that 5,2 on second rotor bad compression?
 
Lubo!

[Grizzly]

Ok if you just have a stock Compression tester you can get a good idea by doing the following.

First remove the Schneider valve from the end of the Compression tester, then remove the EGR fuse and fit the tester to the car, ask a third party to turn the engine over while you watch the needle bounce, if you watch it carfully it will tell you the compression on each bath (it moves quickly so watch closly) then repeat with the rear rotor. There should be three numbers repeated over and over on each Rotor, record what you see and it will give you a rough idea of the Compression.

If you turn it over without removing the Schneider valve it will only record the highest figure and that won\'t be of any use.

[Lubo_car]

Yes, i make this, and i think was on first - 2,5-2,7-2,8, second - 5,0-5,2-5,2.........i know for this testing from other forum, and i make this when i checked my compresion...:Thumbs-up !

[grinder]

with such a large difference in rotors - i would suggest a rebuild

OR

try the ATF trick - that sometimes ups the figures somewhat

[Grizzly]

May be better trying this, not sure how it would work in the car or if it woud get the compression much higher but its worth a go if you are going to have to rebuild it anyway. But tbh that sounds like it neds a rebuild.

http://www.mazdarotaryclub.com/forums/showthread.php?t=30821&highlight=engine+video