1983 Mark VI won't start

[mercurygm88]

So I've been driving the Mark VI a lot lately as I'm having some issues with the 02 Grand Marquis. It's been running good with no issues until the other day. I drove it for about an hour total and was on my way home when it just stalled on me while crusing about 55mph. I figured it was just a glitch, so I pulled over and tried to start it. No luck. I did get it to start a couple of times if I gave it gas but it would stall if I tried to let it idle, ran smooth at higher RPM's though. My boss towed it back to the shop at work and I've messed with it a little but haven't had much time. I have spark and I have fuel, I can press in on the schrader valve on the fuel test port and fuel sprays out a few inches but I haven't actually put a pressure tester on it yet, I think these are supposed to have somewhere around 45 PSI of fuel pressure.. I know there aren't many if any members left who know much about EEC III CFI but I'm hoping someone comes along with some ideas. I'm going to try to rent a fuel pressure test kit in the next few days.

Things I know for sure

The fuel pump is running/I have at least some fuel pressure
It didn't overheat
I have spark
I have receipts showing a double roller timing chain was put in this motor years ago, so it no longer has the nylon timing gears
This engine only has 45,000 original miles on it and has ran great for the 3 years I've owned the car.

[Arquemann]

Is EEC-3 CFI the one that has the crank position sensor?
But is this a "won't start" problem or a "barely runs" problem?

Check timing with a light if you can keep it running for that much.

[sly]

A few inches isn't much pressure. It should spray out and splash off the hood under full pressure. Definitely get a gauge on that.

Fuel filter clogged may be an issue. Might check that.

Fuel pump to fuel pump hanger hose (submersible fuel line) may have cracked.

Fuel relay may not be providing full voltage (crappy old contacts).

[mercurygm88]

Is EEC-3 CFI the one that has the crank position sensor?
But is this a "won't start" problem or a "barely runs" problem?

Check timing with a light if you can keep it running for that much.

It is now a no start issue. Crank position sensor is less than one year old, when the old one went out I lost spark completely. Timing is not adjustable the distrubutor is keyed and you cannot rotate it.

[mercurygm88]

A few inches isn't much pressure. It should spray out and splash off the hood under full pressure. Definitely get a gauge on that.

Fuel filter clogged may be an issue. Might check that.

Fuel pump to fuel pump hanger hose (submersible fuel line) may have cracked.

Fuel relay may not be providing full voltage (crappy old contacts).

I'm definitely going to get a gauge on it ASAP been pretty busy with work and I borrowed a truck from the car lot I'm working for. Fuel filter is less than a year old but who knows how much crud might be in the tank. The old filter seemed pretty clean and definitely wasn't original.

One thing I will say is that I've been running at about 1/4 tank or lower lately, been kind of broke. The day it quit I had filled the tank and then drove about 45 miles before it quit.

[friskyfrankie]

Running low may have dragged some nasty materials into the fuel system.

[Arquemann]

It is now a no start issue. Crank position sensor is less than one year old, when the old one went out I lost spark completely. Timing is not adjustable the distrubutor is keyed and you cannot rotate it.

Mainly meant to verify timing to be where its supposed to be. If a crank sensor or ignition control is conking out, the timing might be all over the place.

If you think its a fuel issue, you could try feeding it starting fluid and see if it wants to run any better.

[mercurygm88]

Mainly meant to verify timing to be where its supposed to be. If a crank sensor or ignition control is conking out, the timing might be all over the place.

If you think its a fuel issue, you could try feeding it starting fluid and see if it wants to run any better.

I'm going to try starting fluid, then I'll do a pressure test. I was wondering if it was possible for the crank sensor or ignition module to go out in a way that I still have spark but the timing is off. When I first got the car in June of 2021 the ignition module was going out and I would lose spark when it got hot, when it cooled off it was fine again. The crank sensor was replaced with a NOS Motorcraft one about a year ago. My local auto parts store can still test the ignition modules but when I worked there they would often test good when they were not because they worked until they were hot. I think I'll have mine checked anyway since it's doing it all the time.

[Arquemann]

I'm going to try starting fluid, then I'll do a pressure test. I was wondering if it was possible for the crank sensor or ignition module to go out in a way that I still have spark but the timing is off. When I first got the car in June of 2021 the ignition module was going out and I would lose spark when it got hot, when it cooled off it was fine again. The crank sensor was replaced with a NOS Motorcraft one about a year ago. My local auto parts store can still test the ignition modules but when I worked there they would often test good when they were not because they worked until they were hot. I think I'll have mine checked anyway since it's doing it all the time.

The TFI in my MGM was bad, it caused hard starting, wouldn't idle cold and generally ran poorly. But when I put some RPM into it, it would run real nice.
Timing control was all over the place. Replaced the pickup and TFI unit, dunno which was the culprit.

[kishy]

I agree with all that's been said already.

I think, in addition to knowing what the fuel pressure is, it would be useful to know if the injectors are firing. Being CFI, you should be able to see fuel pooling on top of the throttle plates (do be mindful that there's a real chance of getting badly burned if that fuel somehow ignited while you were staring at it).

Not EEC-III-specific since I don't know all of its intricacies:
You need fuel, air, and spark, with reasonably good timing.

Fuel: you need pressure and flow. As others noted, verify pressure, and do keep in mind that a plugged filter could still allow pressure without much flow (however, the car would probably spit and sputter and at least try to run if the pump was fine but filter was the problem, unless it is packed solid). The pickup sock in the tank is suspect, maybe moreso than the external filter. And of course, the injectors need to open. The computer probably does this in response to the crank position sensor (TFI cars do it based on...I think it's called IDM, the tach pulse, but you have Duraspark with some other magic bits). The crank sensor is probably being used for both firing the plugs and firing the injectors, so it is fair to assume if one works, the sensor isn't the problem. I think.

Air: it's all around us, unless the air filter is packed solid, it shouldn't be an issue.

Spark: you have it. I'm not sure how EEC-III manages spark timing, but presumably it cranks at base timing (which is that whole non-adjustable deal with the distributor), and then advances once running. If there is a way to disable computed timing (my brain says, maybe the third connector on the weird Duraspark module?) it might be worth checking but not until after you go through the fuel system.

[gadget73]

Crank sensor signal is indeed what triggers both spark and injector pulse. Should be 4 per rotation, functionally the same as a TFI system in that department. On this one the Duraspark box gets timing advance signal from the ECM on that third plug. On EEC-IV the TFI module gets timing advance signal from the ECM through the SPOUT connector. Its all kinda-sorta the same just different particulars.

A bad TPS can cause no-fuel problems, same as it will in EEC-IV. The voltages are different though, offhand I want to say EEC-III uses a 9 volt reference vs 5 volt but don't hold me to that. There is a way to pull codes from it but its a much more limited range of diag and it involves a vacuum pump on the baro sensor to trip the thing into reporting. I'm also not sure if it can store codes. My knowledge of EEC-III is very limited.

but yeah fuel and fire is it. If you have solid spark, fuel is the most obvious thing to look at.

[mercurygm88]

Well it won't start on starting fluid. I'm not 100% sure but it kind of sounds like the timing is off. Not sure how that would be unless either the crank position sensor or ignition module can fail in a way that timing is so far off the engine won't start but it still gets spark.

[gadget73]

try unplugging the advance connection on the duraspark box. I think thats the yellow one but not completely sure. It should be a 2 wire connector, not the one with the white and red wires. R&W are input from the crank sensor.

also just as a dummy check, is the distributor still locked down? If that lifted up for some reason the rotor would be out of sync with the spark and might cause goofy stuff.

how far will the spark jump? Should have blue-white at a half inch or so. if its yellow or won't jump that far the spark is too weak to light the fuel off.

[mercurygm88]

try unplugging the advance connection on the duraspark box. I think thats the yellow one but not completely sure. It should be a 2 wire connector, not the one with the white and red wires. R&W are input from the crank sensor.

also just as a dummy check, is the distributor still locked down? If that lifted up for some reason the rotor would be out of sync with the spark and might cause goofy stuff.

how far will the spark jump? Should have blue-white at a half inch or so. if its yellow or won't jump that far the spark is too weak to light the fuel off.

On my duraspark box the red/white is a two wire plug, the other plug is 3 wire and I believe it is orange, green, and black? Not sure on that but I'm pretty sure there's an orange wire in there. The distributor is still locked down, I used one of those spark testers with the light bulb, I have one where the spark jumps the gap but I'll have to find that to check the color and distance.

[gadget73]

got a screwdriver? Thats usually how I do it. Pull one wire off a plug, stick a screwdriver in there and prop it somewhere thats about a pinky-wide gap.

so the duraspark only has 2 connectors? hm, I thought those had 3. One was input from the crank sensor, one was power input and output to the coil, and the third was spark advance control. Unless thats the setup on the MCU/VV cars I'm thinking of.