In ten years of MX-5 motoring I have never had my car not start up when the petrol tank was half full and the battery charged up. Today it happened, I had pushed my car out this morning when it was cold and frosty, only because it easier to do this rather than get into the car when it is the garage, and also my drive slopes away from the garage which makes it easy to do.
After completing some work in my garage I would drive the car back into the garage as it is too hard for me to push it back in but, the car engine would not fire up even though the battery was turning the engine over. I have never had this happen to me for as long as I can remember as I have one of those charger units that keeps the battery charged up and in good condition.
Any help in diagnosing the problem would be grateful.
As you can see from my avatar, I am no Spring chicken.
Pretty sure that won’t actually warm an engine up.
The cars are getting to be 30 years old now. There are going to be random relay failures more and more. Plus wth imports, most are fitted with some cheap immobilizer from the late 90s; the immobiliser on my Mazda-imported Roadster failed last year, though in my case, it was fairly easy to diagnose that it was the immobiliser. I needed a sparks to get it out (though through him, I discovered that Mazda did the right thing fitting the immobiliser black box under the ECU, rather than throwing it into the wiring jungle behind the dash). Running a check for codes would be a good start. Go around the relays, giving them a tap/refitting, a bit of contact spray. The fuel pump relay is the yellow one under the dash by the steering wheel. There are a bunch of relays (though I think, from memory, lighting-type relays) under the passenger front wing. The fuel injector relay (same one as used in a Ford Probe) in in the engine bay fusebox, the cover of which is often not well fitted, and so exposed to the environment. On a 1.6, I had a relay go bad (or more precisely, a previous owner had fitted a used Ford part, which turned out to be junk). The car would run, then randomly blow the fuel injector fuse while driving (swapping the fuse with a headlight fuse got it going again). It was an ongoing mystery to me (and I gave up), the the garage I palmed it off to, and eventually the auto-electrician they got in, who accidentally diagnosed the issue when he knocked the relay while deciding if he needed to put in a new fuse box or not. The relay, which looked ok from the outside, was a mess inside (looked like water had gotten in). Ironically, Mazda had no new relays in stock, and temporarily, a used part was fitted (eventually a new one was fitted, and its expensive for a relay, £50). Cost me the thick end of £500 for a garage to work out a £50 relay was at fault. So, also check your fuses, though fuses generally don’t randomly blow; replacing a blown fuse is the start of the diagnosis, not end.
After the car has stood all night in my warm garage, heated by an extension radiator from the bungalow I live in, I thought the best thing to do before anything else was to try to start the engine as I normally do. Phew, After just the one turn of the key it fired up OK so I took it for a quick five mile run to clear any dampness that might still be there. Back at home the engine was ticking over just as it should do. I am very pleased that it appeared to only be condensation on the plug leads etc that needed drying out.