Parking Downhill - Won't Start

[arsin225]

Hello.

I'm embarrassed to even ask if this has happened to anyone, but I must know. After looking it up, people have had issues starting their car while parking on a slope. The slope I parked on has been a slope I've been parking on for months, grade is 35-40°. I had 1/2 a tank in there and no noticeable issues lately. Two weeks back I changed my motor and transmission oil, and ran without a hitch.

So today, I tried starting and it wouldn't go. The starter motor was giving er' its all and only on the off chance I would maybe hit 600RPM before it would cut off. So I checked the battery like any sane person and it was fine. Though it was fine I decided to go for a jump, which did absolutely nothing.

I moved the car from a downhill parked position to an uphill ~35°. Still the same thing was happening, but my neighbour the miracle worker said "I stepped on the brake and put in the clutch and it started". The car ran RICH and was smoky for quite some time, probably due to me trying to start it 20+ times with failure.

I drove around started the car back up, no problems. Has this happened to anyone else? I have noticed that parking in a downward position has felt worse during start, compared to flat. I haven't really parked a whole lot uphill. This never concerned me because I thought my car should handle it. I could point to my fuel pump and say it's the issue, but realistically I don't have the experience to say so. That's just what I read online. I also read a maybe hokey engineering decision that "fuel pumps were designed so that in a worst case scenario when going uphill with low fuel, the fuel will flow back towards the pump. A fuel pump failing during a downhill operation isn't as much as an issue."

Any insight to this problem would be great. I know now that the next time this happens I will go to a flat position and wait a bit to test this theory, but what's done is done.

Thanks.

Car specs:
2011 GX Mazda 3, 85,000km
-Known issues: Immobilizer switch is partially fried. Dash flickers/turns off, infrequently, during operation (randomly? unsure what the trigger is)

[Turbospeed_3]

It sounds like your immobilizer is the problem you should look into that and see if you can have it disabled? Being the car is only 5 years old have you contacted the dealer by chance?

[arsin225]

It sounds like your immobilizer is the problem you should look into that and see if you can have it disabled? Being the car is only 5 years old have you contacted the dealer by chance?

I was hoping this thread would die a quiet death. It's not the immobilizer causing the issue. When it does cause an issue at start-up it only complains that I'm putting in an invalid key. I left a key piece of information out of this thread, due to me writing the post in a panic.

My CEL started to blink when my car finally started the one time. For the remote starter, a 'tachometer' signal must be present for manual transmissions. To do this, the suggested way is tapping into any fuel injector, which fakes a tach signal for the auto-stater. While diagnosing the issue of the immobilizer, I unplugged the auto-starter. Leaving the fuel injector line rolled up inside my battery cover. Because the day before that it was a rainy day, I found that there was a little bit of water in the battery case. I do have the cover on and locked, but there was water. Because the fuel injector wire a small pool or little droplets of water, I assume that was enough to screw up the fuel injector comms. Causing my engine to complain, misfire, thus not properly start till the water settled in a different position, away from the fuel injector signal.

I have since then clipped the spade connector, taped it tight, and put it somewhere else.

Mods can lock this thread if they want, it was a silly post. As in life, the answers to your problems are usually where you're not looking.

[r4BBiT]

Out of curiosity why not use actual tachometer signal?

Isn't the point if tachometer to tell the starter engine is actually running? Injector signal would be on before engine runs potentially.

[arsin225]

Out of curiosity why not use actual tachometer signal?

Isn't the point if tachometer to tell the starter engine is actually running? Injector signal would be on before engine runs potentially.

The purpose of that signal is to check if the car is idling.
It's verifying that
a) Your car isn't in gear when you exit the car.
b) No one is trying to steal your car when it has been remotely started.

Why they don't use the tachometer signal directly is a little bit unknown to me. My best guess is because the fuel injectors use PWM to drive the injectors it gives the impression of a AC waveform, which is what the starter was built for. The tach signal for all I know might just be a DC signal that is some ratio of how fast the engine is spinning. Meaning that low voltage is idle, while high voltage is red line.

On various websites including the 12Volt.com (http://www.the12volt.com/installbay/forum_posts.asp?tid=116276) when you look for the tach line, it suggests "Use Fuel Injector". That's just how she goes.

[r4BBiT]

The purpose of that signal is to check if the car is idling.
It's verifying that
a) Your car isn't in gear when you exit the car.
b) No one is trying to steal your car when it has been remotely started.

Why they don't use the tachometer signal directly is a little bit unknown to me. My best guess is because the fuel injectors use PWM to drive the injectors it gives the impression of a AC waveform, which is what the starter was built for. The tach signal for all I know might just be a DC signal that is some ratio of how fast the engine is spinning. Meaning that low voltage is idle, while high voltage is red line.

On various websites including the 12Volt.com (http://www.the12volt.com/installbay/forum_posts.asp?tid=116276) when you look for the tach line, it suggests "Use Fuel Injector". That's just how she goes.
Thanks for explanation. Yea, tachometer it's likely a digital signal.