Won't start -sometimes

[dmccaig]

Dear Panthers,

Last fall, when it got cold, the 89CP wouldn't start. - Nary a sputter. But not every time - just some of the time. Plenty of battery, starter okay, well maintained. Ran fine when it did start. I left the car at my mechanic and he tried to get it to fail several cold mornings in a row - started every time.

Took it Scott for Mods and when he was at the parts store it wouldn't start. So he put a new coil in it and problem gone.

So - this fall, cold morning, won't start. So figure maybe the coil was chinese and failed. Put a new one in, distributor cap for good measure.

Ran fine.

So, this morning in Richmond, chilly but above freezing it won't start. I am hopeful it will when it warms up a little but would much prefer it start every time.

There seems to be a coorelation between cold-ish mornings (though not freezing mornings) and won't start.
Suggestions welcomed.

Donald McCaig

[gadget73]

I think we replaced the fuel pump and ECM relays already, but possibly not. It could be one of those is failing. It may also just be a flaky connection in one of the 4,281 connectors under the hood and under just the right temperature conditions it opens up. If its anywhere, I'd probably suspect the large black and white connectors that should be along the wiper box area, approximately centered behind the engine.

[GM_Guy]

In line with the relays, on cold mornings, resist the temptation to just turn the key to start, turn the key to "run" and listen for the fuel pump to turn on for a couple seconds. If you don't hear the fuel pump whir/buzz/whine/whateversoundyoursmakes then suspect the fuel pump relay. (ECM relay also if the dash lights don't come on when you first turn it to run).

Alex.

[Lincolnmania]

the engine wiring harness connectors could be the culprit but i know for a fact that they have been pulled apart and cleaned at least twice since 2006
the engine computer could be getting flaky, mrltd posted a thread about the problems developing with them due to age that was posted on a mustang forum. the caps bulge and sometimes leak causing all sorts of weird problems.

[Mike_Windsor]

Could it be the starter motor is shot? Like, has a dead-spot in it?

How about the main relay?

[dmccaig]

Dear Panthers,
More detail. Last November, after a six hour run, next morning in the motel, frost on the hood, car turns over strong but doesn't catch. I wait a couple hours it starts fine. I drive it to the sheepdog trial and it starts fine.

Long series of posts on this problem. I drive it home and my mechanic starts it every cold (-30) morning for a week. No problem.

It goes to Skippyville for other repairs and Scott's at the parts store when it won't start. He replaces the coil.

It's getting many fixes and a few mods and stays at Skippyville from - more or less - February until mid August. I expect it's immobile most of those months but used beginning and end as a parts car - point being, not many miles since new coil
put in and NO LONG RUNS and cool morning afterward motel non start. While its there the fuel pump fails and is replaced.

When it comes home, all the runs are short - 2-3 hours out, run the dog, 2 -3 hours home.

Until I do a seven hour shot to South Carolina, park and next morning (frost) it won't start until ten or so when it warms up.
Drive it home, no problem. Drive it to town no problem.
Other then these intermittent failed starts, there's no other problem. No misses, no sputters, no electrical oddness, nothing.
And when it does start it starts right away. No starter grinding or oddness.

But I replace the coil again and the distributor cap and rotor for good measure.

Took it 4 hours to Richmond motel, up early 30ish, won't start. I wait until the sun comes up and it starts and runs perfectly.

That night I had dinner with David Word (who was voted Richmond's best mechanic) and talked about the problem. He thought the best bet was a bad ECM relay or a bad solder. He said it probably wasn't the computer itself because in 40 years of fixing cars he's only had three ones that went bad.

That's the info I have. Now, every time I turn the key on I listen for that fuel pump. I wish I'd listened for it on a cold morning outside my motel after a long run the day before. But - I didn't.

Donald

[GM_Guy]

Listening for the fuel pump will tell you if the relays are making contact (fuel pump relay won't work if the pcm relay (aka ecm relay) doesn't work, hence the need to watch the dash lights as well and see what they do). But if one is bad, buying two won't put you in the poor house. (note: pcm relay and fuel pump relay that you buy today are two different relays, one now has a diode across the coil. So check your wiring color on the connectors to see which is which).

Alex.

[gadget73]

Has to be a flaky electrical connection in the works somewhere that only acts stupid under very specific temperature and operating conditions. That sort of thing is a complete pain in the neck to figure out, just because its so difficult to reproduce. Maybe this is a good candidate for the "wiggle test" mode of ECM testing. I've had electronics and electrical things that chased out to loose wires like this, and its grossly frustrating how many hours it takes to fix them. Once the problem is actually found, its usually minutes to repair but finding it is the issue.

[dmccaig]

Dear Thaine,

It acts like its got spark but no fuel. If it was something in the spark, I'd think it'd show up in a sputter at other times - yes?
Presuming the problem is the same problem it was last November and that the Coil was a separate issue, and since the fuel pump is new with a new connection at that end, wouldn't it be somewhere in the old wires between newly wired fuel pump and ECM?

Donald

[Lincolnmania]

the relays were replaced and the relay holders were replaced to the later style relay center/vacuum tank to accomodate the abs install.......gotta be funky wiring somewhere or like i posted before the ecm is getting flaky http://www.grandmarq.net/vb/showthre...ems&highlight=

[gadget73]

Could be no fuel, but if for some reason the ECM wasn't switching on, it wouldn't turn the pump on either. Its probably worth opening up the ECM to see if anything looks obviously problematic in there. These things are all getting old enough for the electronics to fail. Its probably fixable for the most part but some of those components are pushing their expiration dates. If its just capacitors, thats easy enough to fix but if the caps failed and caused other damage, that might be another story.

[dmccaig]

Dear Panthers,
It seems to have cured itself (now there's a red flag!). Last weekend I drove 6 hours to North Carolina and next morning -frosty - I went out and it fired up just fine.

When I installed the new instrument cluster all that wiring was changed and there's a new alternator. Can't think of why else it works now - the fail was pretty predictable.

Donald

[jaywish]

Pennies from Heaven?

[dmccaig]

Pennies from Heaven?

Rewiring speedo, gas gauge (new sender needed, warning lights, oil, temp and ammeter, plus tach and changing mechanical gear shift indicator to electric was beaucoup pennies. But that frosty morning start is heavenly.

Donald