My turn to ask for help

[Glacier991]

Ok, I am usually one of the ones offering advice, but every now and then we all get the need for more input and help. My question relates to a 93 Merc Sable (hey it's FORD, give me some slack here!).

Anyway about 6-8 months ago on a few occasions when I tried to start it it would spin the starter nicely, with nothing firing up. I figured it was ignition or fuel, and cycled the ignition switch a few times (without engaging the starter) and then when I tried it, it would start. Then for a while (weeks months) it was fine. Then my daughter had the car and was stuck at a gas station 20 mins away. When I got there to rescue her 30 mins later, it fired up... 3 months pass, runs fine....this weekend I drove it to the Sierra.... was a long slow ride up, and it was running warm... not over heating but over half way up the temp gauge (which seems pretty accurate with coolant temps on the scanner readout). As I turned off the freeway as was winding up a residential street it started acting funny... I at first thought it was transmission, but then realized the engine was dying, and eventually did die. I could not restart it. I parked it and walked the last 1/2 mile to my destination.

Next morning started fine, drove it to where i was staying, and this morning 100 miles home.... ran fine. No problems at all.

Now from a prior experience with my explorer, I have been assuming the fuel pump is dying. That is still my main guess.

I ran codes, both fast and slow, KOEO and then KOER. Nada.

Now I mean I'm not anxious to drop the fuel tank... nor am I anxious to unnecessaarily replace a relay... so, with that history, I ask YOUR help.... ideas and thoughts. I could be way off base. I have also wondered about a vacuum condition in the fuel tank, but cannot verify that.

(Kinda fun to be on THIS end)

Thanks!

 

[splodo49]

Maybee debris in the fuel tank,or loose wire,bad connection.

 

[Glacier991]

good points all... and all probably drop the tank solutions <sigh> I mean if I drop it I may as well replace the pump. 11 years old 120K....and check for those things too...

I hadn't considered the effect of debris clogging the filter, than falling away. Works for this last weekend as an explaination... but those other times? Hmmm..... I want you to know I appreciate all viewpoints. Not rejecting any. All too often on here someone asks for advice and when they don't like what they hear they reject it and ask.."next?" like we are suitors in a dating game.

If I do nothing else, based on your comments I will definitely flush the tank while I have it out. (which I suspect I will). Thanks!

 

[Iggy flywheel]

Back in the old days when you had a problem engine die. Let it cool or sit while it turned out to be electrical. ie the coil was bad or condensor. since they don't have them things anymore check coilpack. Before you drop the tank should test fuel presure. I think you looking at a electrical problem not fuel.

 

[Iggy flywheel]

Oh the epoxy on the wires inside the coil would get hot and melt causing a short then would cool fixing the short.

 

[Glacier991]

I had thought about pressure testing.... but wondered if the fact it was intermittent might say something.... then again if it was borderline low.... good thought. The main reason I thought fuel pump was it rather mirrored my Explorer fuel pump failure pattern.
I neglected to mention the Sable is Sequential fuel injection... if that matters. Thanks for weighing in... hmmm I'll have to investigate the ignition system... see exactly what setup it is and hook up the scope and see what it looks like "healthy". I hate intermittents. Thanks for the good advice!

 

[wattsgame]

i had a similar problem lately with the wifes mustang turned out to be the fuel filter.

 

[DeRocha]

I've heard of electrical problems caused by heat.. Anyway the Heat will cause wires (E. Ignition etc) to expand and gradually loose continuity, when they cool off and contract continuity is restored and your good to go...

 

[Runnin'OnEmpty]

Chris, I'm pretty sure the 93 Sable has DIS (like our Explorers), but also has an external ICM/ignition control module. It sounds like the ICM is going bad, because of the restart ability after it cools. Does the tach act up when it starts to die, or has the tach acted up in the past? That is a dead give-away for a bad ICM. Sometimes the tach will read double the actual rpms, then return to normal.....

Ford had lots of trouble with ICMs in the early 90s, and had recalls on several models. They solved most of the heat related problems by mounting the ICM on the intake manifolds, which is where your's probably is located.

I absolutely despise vehicles that strand you on the side of the road.....

 

[Doubt Incarnate]

i second that, i have a cavaleir i had as my first car, and it always had icm problems. it used to give false tach readings, stumble off the line, and when the icm died, it always took the coil down with it. autozone parts are the devil. the last time i tried to start her, guess what! no spark, just crankity crankity crankity and the smell of gas.

 

[Glacier991]

I realize this is EEC-IV, but would it throw a code with a bad ICM, or not? And as for the tach, I've not noticed anything in particular...thanks for all the help everyone.

 

[jimbo74]

try replacing the relay.. the relay for the fuel pump is under $10, and cheap insurance... it's still summertime out where i live, and the relay on our 96 explorer with liek 190k on it now sometimes sticks and wont allow the truck to restart..... i replaced the fuel pump on the explorer last year

 

[410Fortune]

did you lsiten for the fuel pump when the problem occured?

check fuel pressure at the rail during idle?
This is the best way to spot a weak/failing pump.

 

[Glacier991]

Ok, after listening to you folks, and doing a little more research, I am realizing that the Sequential Fuel Injection uses the PCM and therefor I am assuming something really wrong in that system MIGHT throw a code, which I do not have. So here's my "current" plan:

First, I have had this car for about 4 years, and it now has 120K on it. Replacing the fuel filter can't hurt, so that's number 1.

While I hate throwing parts at a problem, I tend to agree with Jimabena74 that for $10 a relay is cheap insurance. When I replaced the fuel pump on my explorer last year, I went ahead and replaced the relay too at that time. So, new relay. (and a slap on the hand for utilizing this approach).

I'll check the pressures at the rail, but my expectation is that I will probably find them ok... we shall see.

On the ignition side.... gonna price an ICM, may replace it if it's not a $100 item. Gonna check the coil pack visually and see if I notice anything... I am also gonna scope it and check the firing voltages.

The fuel pump on these beasties is a high pressure high output model for the SEFI system, and deep down still my prime suspicion, we'll see what idle fuel rail pressures are.

Because the problem is sooo intermittent - [First delayed start was 6 mos ago (cold) and then a 2nd one (hot) a couple weeks later... then months pass, and my daughter has the non-start situation I described (hot)...a couple months pass and I have the DIE while operating and no restart situation of last weekend (HOT).....] the following does not come as a surprise, but because the Ford SFI 93 puts out datastream like a OBD-II, I drove the car this morning with the scanner hooked up. Everything perfectly normal. short term fuel trims zero (!) long term -6.

I'll report back what I find out. Again thanks all for your input here. This forum is a great place to collectively troubleshoot things.

Any further thoughts or ideas are welcome.

 

[410Fortune]

The relay is cheaper then $10 at AutoZone, more like $3 and is a direct replacement that will fit int he Ford harness/box

I have to date seen 4ea 93-94 PCM's themselves go bad, causing all sorts of intermittant issues, engine fall flat on its face, etc. No CEL when this happens.
Junk yard replacement PCM = $60 approx. I have a couple of 93-94 Explorer PCM's I keep around just for testing this. However IMO your problem seems to be more fuel pump related, being intermittant and from the symtoms you describe.

Coil packs, do fail, but NOT OFTEN, when they do go bad it is usually kaput, no more worky.

 

[Rhett]

I assume you already checked the PCM to see if the plug is coming loose in there. The intermittent stuff, blech, hard to diagnose

I too like the idea of changing the fuel pump relay, only because that's cheap and easy. I agree the pump itself could be worn out. Does it make any difference in the behavior if the gas tank is full or nearly empty?

One other thing I have seen is an O2 being bad, but yet for some reason not throwing a code. The said O2 was even heat tested and it failed...yet no code was ever thrown. I've still never figured out why no code was thrown. Quirk of OBD-I maybe? Vehicle symptoms were dying when the engine was warm, and not wanting to start again until the vehicle had cooled for a while. Yours dies at cold, hot, or whatever so that may not be the same issue.

 

[Glacier991]

Rhett... the 02 sensors were looking real good on the scanner today - corssing over at a nice clip - and they usually just get progressively slower, rarely intermittent to my experience unless it is a wiring issue. Fuel tank level is an interesting idea, and about the only think I can say is it was at half tank this weekend when it dies. My daughter was stuck with it at a gas station, but she's 18 and well, if she puts in gas, it's rarely to fill it. (smile).

And I WILL double check the pcm plug, good idea (I'm getting lots of good ideas here!)

 

[Glacier991]

Ok update time. First a couple of observations. Though this was not MY car when new (I got it 4 or 5 years and 60,000 miles ago) the original owner BOUGHT THE FACTORY MANUAL FOR IT! I cannot tell you what a great idea that was and is! Was very helpful tonight. Second, I am thinking a brief "Diary" on fuel issues in a fuel injected engine may be a good idea for some of the newbies..... As I bled the pressure off I wondered how many poeple didn't realize how these worked. Something as simple as replacing a fuel filter could be dangerous! Anyway, I digress.

The Sable (Taurus in Mercury clothing) uses a vacuum controlled fuel pressure regulator (FPR). When I checked the rail pressures with the engine running and the FPR connected acceptable pressures were 30-45 psi. I was at 30. When I disconnected the vacuum (disabling the FPR's ability to "regulate") I got 40-42 PSI out of the pump. I'm thinking the FPR may be a little tired.... yet...

That doesn't seem to explain the problem to me. I'd not expect a vacuum operated device to be "intermittent". Am I off base?

So anyway it doesn't change much except I think I am going to replace the FPR as a matter of course, AND the filter AND the relay.... and keep my tank below 1/4 constantly for a while (so if I have to drop it it doesn't crush me).

With this new info, any new thoughts ?

ps. The manual had a series of pinpoint tests, I didn't follow through on them all but will...mostly curious about the amp draw on the pump at this point.... the rest I read and frankly think I'd pass, on the low side.

damn intermittents.

Still leery of the pump.

 

[lifeguard379]

my mom had a tempo that did the same thing and it was the icm.

 

[Brian_B]

Hmmm....just an idea to check, but the inertia switch was intermittent on my dads honda and my old ranger (different times). When they would not start we would bang on the switch and they would always fire right up. Have you pulled it and jumped across it (for testing purposes only) when it won't start?