mx5cartalk.com

Above is the issue, the long story is how we got there.

A while ago I was unscrewing two phillips heads to the afm and not once did i think 'if there are screws here i should probably not take this out'. So i did, made a mess, and was running with an afm with the plug 'arms' just resting on the circuit board.

Then i had the bright idea to get a new afm, found one, but the wrecker had cut the wires about 5 inches from the plug and extracted the afm whole. Bugger it I thought, I'll just do the same to my crap one (which still worked but wasn't sure when it wouldn't) and solder it all back in. I should have been a butcher i know.

This worked, no problems, had a great run to Berry and Kiama yesterday no dramas.

Today though went to the local shops on the way back the car sounded like it was running out of fuel then died. Wouldn't start again.

Now my assumption is that the afm and rewiring of it were fine considering the run yesterday.

I have checked the fuses in under the bonnet, all look good and whole.

Checked the fuel pump and didn't hear it run when key on.

Took it out, wired it to battery, runs no problem.

At this stage, without a multimeter and having checked the pump for functionality, knowing the bodgy wired afm is fine from yesterdays running, I'm inclined to think it's the fuel relay under the dash.

I will get a multimeter this week to check the plug that goes into it but I guess after fiddling with it all day i'm asking someone to say 'yeah that's what it looks like'.

All suggestions welcome, and no offence will be taken if one of the suggestions is don't touch your car anymore.

[Best Black Adder voice] BALDRIC! [/end]

Yes, I too have un-screwed the panel on to of the AFM and broken some of the fine wire connections in there ( ).
You do know that the cable to the AFM can be unplugged at the AFM? You should have been able to unplug the cut cable from the wreckers and plug your existing cable into the replacement AFM.

When you say won't start. Do you mean it runs for 2-3 seconds and then dies, or won't start at all? If runs for 2-3 secs then it is most likely fuel system related. Try connecting (jumping) the FP (fuel pump) and gnd (ground) connectors in the diagnostic box in the engine bay. This bypasses the airflow meter and COR (Circuit Open Replay), and keeps the fuel pump running all of the time. If this works then there is a problem with the airflow meter or the COR....could be a bad ground connection. Given that you have solderd/re-wired the connection to the AFM I would start there....I know you did a long run yesterday, but you need to start with what has changed since it last ran.

Another possibility is that the ignitor module (drivers side in engine bay) has died. I managed to short two when I had my fuel problems. I was running on two cylinders when one failed and none at all when the 2nd shorted. A new part of Mazda is $$$expensive. Trident industries make an aftermarket one here in Aus, most Auto shops can order them in for you at less than half the price of the Mazda part.

Lastly, here is a good thread on the big forum that will help investigate and hopefully resolve your issue.

http://forum.miata.net/vb/showthread.ph ... tarts+dies

Let us know how you go.

J.

Yep, found the two spring clips after taking apart the old afm plug to investigate the connections, unfortunately was a little too late for the replacement. I certainly know now though

The first thing i did when i got towed back was check the afm connections as I thought maybe something had come loose at some stage.

Car doesn't start at all, the pump is not getting the signal to send fuel.

Tried the fp to gnd as well and still no fuel coming through and pump not starting.

Today, I buy a multimeter and check the lot front to back.

Baldric1600 wrote:Yep, found the two spring clips after taking apart the old afm plug to investigate the connections, unfortunately was a little too late for the replacement. I certainly know now though

The first thing i did when i got towed back was check the afm connections as I thought maybe something had come loose at some stage.

Car doesn't start at all, the pump is not getting the signal to send fuel.

Tried the fp to gnd as well and still no fuel coming through and pump not starting.

Today, I buy a multimeter and check the lot front to back.

Check the EGI main relay, it's the big green one in the underbonnet fuse box. Look to see if the NO terminal is burnt out. Should be $5 to $25 for a replacement from a wrecker, $120ish new from Mazda. It supplies power to the fuel pump and sender, so if your fuel gauge is moving around a lot it can mean that the relay is on the way out.

Well, i may have spoken too soon. Got my new toy multimeter and pretty much followed diagnosis of this fellow at miata.net http://www.miata.net/garage/fuelpumpdiag.html

Of course, I did it ass backwards.

Took the plug from the fuel relay (of course i broke the clips, i think the old man used to call me passion fingers as i recall) and tested the wires mentioned in the link for 12v, and they were fine. So signal getting to relay. Plugged it back in.

Shorted F/P and GND turned key on and tested blue wire with red strip and black at the fuel pump under the access plate up the back, which is also conveniently located under the roll bar. 12v

Took the paperclip out and tested again turning the engine over (my wife is fantastically patient). Got 10v.

Tomorrow, because I don't really want to get dissapointed on a monday night, i'll take the whole assembly out of the tank and do as above right to the pump proper.

I guess if i get 12v there, it's the pump, yet when i tried the pump on the battery it went like a champion. Can't be a really clogged filter because you'd hear the pump at least labour trying to do it's job.

I'm still ruling out my dodgy afm assembly, as every now and again turning the thing over a bit of residual fuel or maybe vapour gets in and it teases me with a potential catch, thinking it'll start. And of course the fact that power seems to be getting to the pump after all helps.

I have a cunning plan to put in play tomorrow

there's also a fuel pump cutout in the afm, but this is supposed to kick in just after startup if the correct signal is not present. No correct signal could be the afm not seeing airflow, the afm not being correctly wired, or the afm not being present & wiring adjusted accordingly.

When my egi main relay died, I could still measure 12v at the pump, but the voltage broke down under load (i.e. trying to start the car)

back in a couple of days, going to start from scratch.

Bit more info in these ref afm fuel cut out in case it's of use:
Middle of: viewtopic.php?f=29&t=21251&hilit=afm&start=30
Bottom of: viewtopic.php?f=29&t=21217&hilit=afm

thanks guys, back in a couple, while i was going erratic on this i'll now go systematic and hopefully find an answer as my last post.

give me a couple and i'll get back with something positive, i hope, or a plan to take Tojo somewhere for a fix

(finally found a name for my car, hope it's not offensive)

Fuel Pump .... my pump became eratic for weeks before finally, it died - bench tested it and was working fine too - wasted so much time trying to diagnose it.

MX5CHIC you nailed it.

Went through all the wiring and all good, got the pump out yet again for testing on the bench, worked, then didn't, then did, then didn't then gave it a tap and all good. Put it back in and tested under load shorting gnd and fp, erratically is the operative word, almost played a tune in inconsistency.

Nice learning experience, bad time to give up smoking though, then again maybe not when playing with an open tank

Another nice plus, when it did work was able to start the car, so my dodgy afm installation is still dodgy but functional

Thanks to everyone for posting replies, your advice has been really appreciated. Hoping to join the nsw club shortly and get on a track day Feb 14th. Though Mrs Baldric may have something to say about that

It'll be good to have Tojo back on the road again, yay!

Great to hear you fixed it ..... I still kick myself when I think how much time I wasted on tracking down the problem