1999 Mazda Eunos Hot starting / running problems.

Tiny
ROCKETTPUNK
  • MEMBER
  • 1999 MAZDA EUNOS
  • 1.6L
  • 4 CYL
  • RWD
  • MANUAL
  • 120,000 MILES
This has been going on for a little while, and I have some ideas, but would like a second opinion.

*Car doesn't want to start when hot
- turns over strongly, but doesn't catch
- if it does catch and hesitantly start, it will run fine
- no hesitation on load when accelerating
- after about 30 minutes, the car will start again and run well
*Car has twice cut out when hot when coming to a stop - the revs simply drop off.
- no symptoms before this happens
*At MOT the emission readings were high and JUST passed
*Fuel economy isn't as great as it could be (but not horrendous, just worse than some other's of the same spec)

I have checked the thermostat, which functions correctly, as does the electric fan, the radiator was changed last week and is functioning perfectly - so it is not an overheating issue.

I removed the Cam Angle Sensor, cleaned and re-installed. I have yet to do the same with the Crank Position Sensor.

As there is no misfire, or hesitation, I doubt it is the ignition module or leads. I have visually inspected them and they seem fine.

My three suspect parts are: Cam Angle Sensor failing, Crank Position Sensor failing or engine block temperature sender failed / failing and reporting back to the ECU that the engine is cold always.


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Monday, April 20th, 2015 AT 2:39 AM

6 Replies

Tiny
HMAC300
  • EXPERT
We don't have that car in US so no info but check fuel pressure with a gauge may be low and clean throttle plate on both sides and iac hole with choke cleaner may be your problem of not running when coming to a stop
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Monday, April 20th, 2015 AT 7:03 AM
Tiny
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Thanks for the reply. The Mazda Eunos is exactly the same as the Miata, it's just the Japanese badging.

I have looked at the inlet, and everything is clean. The injectors look perfect also; same with the fuel filter, so I would assume fuel pressure is not an issue. Also, would fuel pressure being low not cause general running problems, other than when the car is hot?
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Monday, April 20th, 2015 AT 7:15 AM
Tiny
HMAC300
  • EXPERT
It may run ok until it gets heated up then the fuel pump won't put enough pressure out as it may be getting worn. That is why you check it with a gauge and it may effect your problems coming to a stop as well.
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Monday, April 20th, 2015 AT 7:24 AM
Tiny
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Super, well that's on my list of "to checks".

What do you think of the possibility of the other things mentioned in my first post, being the culprits?

The only reason I feel fuelling isn't the case, is it seems to be using more fuel than usual, rather than less.
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Monday, April 20th, 2015 AT 7:31 AM
Tiny
HMAC300
  • EXPERT
If anything I'd say a crank position sensor getting hot and having to many ohms and not working until it cools down. Coolant temp sensors are more of a cold start problem than hot
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Monday, April 20th, 2015 AT 9:54 AM
Tiny
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You're a star. I'll try that and get back if not.

Thank you
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Monday, April 20th, 2015 AT 10:23 AM

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