Durty Reader
10/3/19 9:08 a.m.

Edit: the car is running, bad coil packs. I swear I had spark when grounding the plug to the anti roll bar. Thanks to everyone.

Original post:

I really tried, I love the idea of keeping old fun cars alive, and I'll admit to being a hack mechanic, but here we are.


I recently moved (July) and drove my miata 400 miles and parked it for a month on a battery tender. When I came back out it sputtered and died within a few seconds.


After that it wouldn't start at all. I checked that I'm getting spark at cylinder 1 and I am. My camshaft is visibly turning over. All my spark plugs are oil fouled so I changed them anyway without any improvement.


I rented a fuel pressure tool and after pulling the injector relay and turning over the engine to depressurize the system I hooking up the gauge to the pre rail line the car actually fired up! The gauge read 30 psi and held while I revved it.


That night I took a 30 minute drive around and red lined it to give it the old Italian tune up. It felt like it had a few months ago.


The car sat a few days and now won't start again. Turns over strong but I get nothing. A friend suggested starter fluid to help delineate spark vs fuel issue. I got no kick over with a few sprays of starter fluid.

I checked the cylinder pressures and they're all 150-160 which isn't the healthiest but doesn't seem like it's my problem.

I'm at a loss. 

So GRM braintrust please give me something else to try.


Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
10/3/19 9:31 a.m.

First, it's almost impossible to stop them from cranking. That's a really simple system. So that doesn't tell us anything other than the fact that your battery tender works :)

My first thought it that it's a dodgy main relay. It's a known problem, although it would also take out spark. Do a quick check and see if you have 12v on one of the two injector wires (white with red stripe, I think) with the ignition on. If not, then it's the relay. When you were dinking around with the fuel system, you may have temporarily fixed it. If that relay goes down, the ECU shuts down so you don't get fuel or spark. 

30 psi of fuel seems awfully low. I don't recall the specifics, but it should be tied to manifold pressure.

tux424 New Reader
10/3/19 9:36 a.m.

Intermittent fuel pump issue?

Do you hear the pump priming when you turn the key to run (without starting). 

How long are you cranking before you give up? I've seen failing pumps lose pressure over a few days, and have to crank a few time (key on/key off cycles) before they would run.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
10/3/19 9:41 a.m.

IIRC the 1.6 doesn't prime the pump, it doesn't come on until you start cranking. You can force it on by putting a jumper in the diagnostic connector.

Donebrokeit SuperDork
10/3/19 9:50 a.m.

Sounds like a fuel delivery issue to me.


Might want to pull the plug from the top of the tank/ pump housing and see if you have any crossion in the terminals. I have seen this more than a few times. Good time to check the voltage and ground.

Durty New Reader
10/3/19 10:20 a.m.


I got 12.39 volts at the cylinder one injector with the key on run. It was red/white.


Thanks for the quick response. 


It's a 1.8 but I don't think the pump primes automatically either.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
10/3/19 10:45 a.m.

So your main relay is good. Doesn't mean the fuel pump relay is, but the main is!

My bad, my head said that was a 1990. It should run the pump momentarily with key-on. I'd be checking the fuel pressure again.

Vigo MegaDork
10/4/19 9:43 a.m.

Generically speaking if you have ethanol blend gasoline that sits for a long time, the water it absorbs settles to the bottom because water is heavier than gasoline. Your fuel pump sucks from the bottom of the tank. That problem would clear itself up pretty quickly, but if you've already sprayed water on all your spark plugs by then, you're going to have to wait for them to dry out before they'll actually spark again. In 'cranking the engine' terms that would be practically forever, maybe 30s-1min. Maybe enough to burn up your starter! On the other hand if you cranked the thing for 10 or 20 seconds and it didnt start but you then came back 30+ minutes later and it started right up, that would make sense with  this theory.

So, my guess is water in fuel which fouls spark plugs leading to crazy long crank time. Get it running one more time and dump some fuel stabilizer in it (or empty it and add ethanol-free gas, more difficult) and drive around for a while and report back in a month? cheeky

morello159 Reader
10/4/19 10:40 a.m.

Clogged fuel filter?

Durty New Reader
10/5/19 11:03 a.m.

It doesn't cost much to replace the fuel filter so I think I will and I'll recheck the pressures at the pump.


Vigo I just didn't get any mileage at all from putting in brand new plugs. It didn't change a thing.


I appreciate the help guys and I'll keep plugging away this weekend.

Vigo MegaDork
10/5/19 9:50 p.m.

Vigo I just didn't get any mileage at all from putting in brand new plugs. It didn't change a thing.

Until you cycled a bunch of fuel through the system by depressurizing and repressurizing the system.  Granted the time intervals between things you tried weren't listed.  

Pete Gossett
Pete Gossett GRM+ Memberand MegaDork
10/5/19 10:06 p.m.

In reply to Durty :

Your symptoms sound very similar to my fuel issues I had last year. A new pump, sock & filter, and wiping out the bottom of the tank while I could reach in, cured my problem. Follow Keith, advice & check your FP relay ,or just replace it preemptively. 

Durty New Reader
10/6/19 9:08 p.m.

That's the fuel pump plug. It's really clean. This car only has 80k miles.


The new fuel filter didn't do anything, but it really shouldn't have since I had 38 psi with the fuel pump wired "on" in the diagnostic box. It held pressure and after 7 minutes it was still 31 psi.


Whoever put on the fuel filter cover last stripped 3/5 of the plastic screws so I had to drill them out.

Durty New Reader
10/7/19 7:26 p.m.

I just watched the video and the revs aren't registering when the starter is cranking. Is that normal or could it be a problem with my camshaft position sensor?

Durty New Reader
11/7/19 9:26 a.m.

I drained all the fuel out of the tank in case that South Georgia station I filled up had excessive water in the fuel. I put in a new 2 gal after removing the 8 gal in question. 


That didn't help either. I'm running low on options and I would rather not have to go to a real mechanic, but that might be my only option unless we can think of new things to try. 


Take off the valve cover and make sure the timing chain isn't broken? What else would y'all look into?

Stampie GRM+ Memberand UltimaDork
11/7/19 9:44 a.m.

Have you checked for spark?  If it's a 94 iirc the tach signal comes from the coil and is a one year only part. 

Durty New Reader
11/7/19 12:52 p.m.

It's a 95, but I've checked cyl 1 and saw a spark when the plug was grounded to the strut bar and my wife was turning it over. 

i haven't checked the other three.


also I appreciate Stampie, KBBL's gonna give me something stupid!

alfadriver GRM+ Memberand MegaDork
11/7/19 1:24 p.m.

With your wife cranking the car, see if it will start on carb cleaner.  If it does, then you need to change the pump.  I did that with my 99, and had to change the pump.

Durty Reader
11/7/19 1:42 p.m.

In reply to alfadriver :

I did that with a few sprays of starting fluid in the air intake behind the air filter. I got no kick over. How much fluid would it take to be a definitive no spark situation?

alfadriver GRM+ Memberand MegaDork
11/7/19 1:59 p.m.

You can be generous with it.  Heck, you can spray it in (a lot of it) and then you can try to start the engine.

Vigo MegaDork
11/7/19 2:25 p.m.

It's apparent from the sound in the cranking video that you have some compression on all cylinders. You have fuel pressure and power to injectors. That doesn't mean they have a switching ground like they're supposed to and actually opening and spraying, but if that was the problem starter fluid would allow the engine to run briefly. If you have compression and starter fluid and it still doesn't start you either have no spark, or spark that is way out of time. So, i would try starting fluid again, and if that doesn't work then verify that spark exists, then that it's timed properly. 

Harvey SuperDork
11/7/19 4:16 p.m.

ECU gone bad?

Durty Reader
12/9/19 9:40 a.m.

Well I took it to the local Mazda shop, first he suspected the CAS so he had a second that he was able to plug in and by turning it over we did not get spark between the coil pack and the wire. 


Now I swear I had a spark when I grounded the plug to the front roll bar, but he dug in and found that the coil packs were bad. 


Thankfully I have a running miata and new (used) coil packs.

Thanks to GRM for all the help, but I obviously wasn't able to give you the right information. 

Back to the track with my new Hard Dog tow hitch

Vigo MegaDork
12/9/19 9:32 p.m.

I really love hide-away hitches. Congrats on both a running car and a hide-away hitch.

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