1989 323 -- hot no-start

[swivel]

So, after a few weeks of getting 30 mpg on regular in the 323 (yay), I've been hit (twice now) with a no-start issue.

It happens under heat-soak conditions, i.e. Driving, stop off at a store for 10 mins and come back out.

What happens is this:
1) Go to start car, makes like it's going to catch as always, but stumbles for about 3 sec like it's not firing on all Cylinders.
2) Car dies and floods.
3) There is no getting the car going again while it's still hot. After it un floods, I can repeat step 1 and it will proceed directly to step 2 until such time as the car has cooled down enough -- Then it starts as if nothing ever happened.

Previous to this, under a hot start condition, it would start, although the idle would be a little low and tiny bit rough for about 30 sec.

I'm guessing, that this new problem is an extension of the old problem, just whatever sensor might have been starting to go is going more.

Any suggestions on what to check?

Coolant sensor?
O2 sensor?

It's a really simple setup on this car, without a lot of sensor inputs -- normally I'd suspect like the Crank sensor -- but this car doesn't have one.

Just looking for some suggestions.

[Demon_MX5]

plugs, wires, ingintion? I'd check all those first

[swivel]

Right, sorry for the lack of detail. Had a full tuneup -- plugs, wires, cap & rotor as part of the engine swap project -- so they all have about 600 miles on them. I've confirmed spark while cranking.

[hobie237]

How is the fuel pressure?

[hobie237]

In addition, is it throwing any codes?

[swivel]

I stopped by the car on my way home from work and discovered that in fact there is no fuel pressure. I came home and consulted the shop manual. I'll be going either tonight or tomorrow morning to test for power @ the pump and continue diag from there. At this point, it's either the relay or the pump. I'm actually hoping it's pump, as the relay looks like it's a @#$%! to get at -- where I get to the pump via an access hatch under the back seat.

I don't have the special mazda test to read the codes out of this thing -- not that it stores codes as such -- I also don't have an analog volt meter to "read the needle sweeps". Gotta love computer systems with no good way to diagnose them ;).

[swivel]

Well, when I went to diagnose further this morning, the fuel pump sprung to life and the car started as if nothing was ever wrong. I'm really suspecting the relay at this point. I'll have to diagnose further. I feel like there are two ways to test for an intermittent relay failure:

1) Swap it out and wait for it to happen again (on the edge of your seat every time you start the car, hoping that was really the problem).
2) Wait for it to happen again and swap it out (hoping that was really the problem and you'll be able to be on your way).

I really don't think it's the pump, as I've never heard of a pump dying and coming back to life on it's own, and the connections to the pump look good. Of course, since I had power to pump right away it's difficult to trace the power through the system and find the hold-up.

[hobie237]

If it's a relay, I'd replace it and not wait for it to go again. Check the connections between the key and pump, too.

[swivel]

Fuel Pump!

When I went to drive the car home last night it was intermittently low on power, especially going up hills (classic bad fuel pump symptom). Then about 1/2 mile from my house it sputtered and died. I pushed it into a parking lot and went back after a couple hours, hoping that I could get another start out of it, after the pump cooled down -- I'm assuming now that is what's happening, the pump is just overheating as it's always getting power, ruling out the relay and connection problems.

Indeed it started, and I wasted no time, not knowing how long it would last this time. So I gunned it up main street trying to get home as fast as possible, speeding tickets be damned. Of course as soon as i turned off main street, I got stuck behind someone going 10-15 mph. Not 10-15 under, 10-15.... <think> OMFG, I have a finite amount of time before this thing croaks on me...ARRRGGGGHHHHH GO!!!!"</think>
I eventually got out from behind this person and turned onto my street. As I crested the final hill before my house, it died. Luckily it was all down hill to my driveway so I coasted home. Getting into the driveway took some doing, as the first part of the driveway is about 6 feet of a steep uphill. So I picked up as much speed as I could to make the 90 degree uphill into the driveway with no power steering....

Now to order a fuel pump...why are they so expensive?

[hobie237]

There's a bright side- you'll likely get another ~20 years out of the new fuel pump, and from a troubleshooting standpoint, it's way easier than rooting out an electrical gremlin. ;)