SOLVED: familiar song...SC sat for years, won't start, running out of ideas

hulakai

Registered User
Hi all...hoping for some "been there done that" advice.

89 SC 5 speed
Sat for 14+ years after a rebuild of motor
Was running when parked and was moved a couple of times under it's own power but then sat for years

It won't start. Not even a hint of combustion. Here's what Ive done so far:


Changed fuel pump, filter, fresh fuel
Fuel pressure at shraeder valve on rail is 40psi
Spark on all 6 posts of coil pack
Noid light is flashing on injector 1 (or is it 4?) (haven't tested all injectors yet, but again not even a hint of firing.
Tried a known good DIS. No change
Tried a known good '89 ECU. No change

Only ECU code I've seen is 95 (Fuel pump circuit open, ECA to motor)

Fuel pump IS running momentarily when turning key and pressure is consistent during cranking.

My current suspicion is that there's a ground corroded or insufficient or just plain missing because oof that error code and the engine being reinstalled right before it was parked. The install doesn't look too great so a missing ground strap would not surprise me, but it did run after the engine was put back in.

Does anyone have some suggestions for next tests, or perhaps info on where/how engine should be grounded (factory locations or better)?

Thanks much in advance. Hope there's lots of folks still here. Surviving MN12s are getting rarer every year.

Kevin
 
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14 yrs. corrosion is not your friend. Death by sitting lives there.

Grounds first, then relays, not forgetting the IRCM. Be sure to have more than 11.5 volts in the harness when attempting to start Then you have mechanicals like stuck rings, failed fuel pressure regulator, etc. etc.

See this link for a process that should help: http://mnharms.com/tutorials/disnostart/
 
14 yrs. corrosion is not your friend. Death by sitting lives there.

Grounds first, then relays, not forgetting the IRCM. Be sure to have more than 11.5 volts in the harness when attempting to start Then you have mechanicals like stuck rings, failed fuel pressure regulator, etc. etc.

See this link for a process that should help: http://mnharms.com/tutorials/disnostart/


Thanks for the quick reply. I agree....sitting that long is never good. But it was indoors...not heated mind you, but indoors. And it cost me $200, and the rockers aren't totally gone (yet)... so I figured what the heck.

I hadn't even thought about the IRCM so thanks very much for that.

K
 
Is the upshift light on when cranking the motor?

No it's not....I should have mentioned that.

Swapped out the IRCM with a known good one, no change.

I noticed a grounding point on the frame, passenger side near the front. Nothing attached. I still suspect bad grounds but what's driving me mad is that I have spark, fuel pressure and injectors receiving signals. The car should at least cough shouldn't it? What could block the car from starting or at least sounding like it wants to when it's getting fuel and spark? What am I missing in the basic loop here?

The noid light didnt flash very bright but Ive read thats normal because the pulse is so brief. True?

Spark tester was set to a pretty large gap and it arced consistently.

Still no codes.
 
noticed a grounding point on the frame, passenger side near the front. Nothing attached.

That's a key ground path. There should be a short, clean grnd. cable (not just a wire) running from one of the pass. side motor mounts over the frame.

Sorry if I missed it - did you check the impact fuel safety switch in the trunk? What did you learn when you ran thru that linked no-start troubleshooting process? How old is the fuel?

How many volts at the battery? With the headlights on, do they dim while cranking?
 
That's a key ground path. There should be a short, clean grnd. cable (not just a wire) running from one of the pass. side motor mounts over the frame.

Sorry if I missed it - did you check the impact fuel safety switch in the trunk? What did you learn when you ran thru that linked no-start troubleshooting process? How old is the fuel?

How many volts at the battery? With the headlights on, do they dim while cranking?


Thanks very much....I knew that ground would be important but wasn't sure where the other end goes. I'll have to pick up a couple of straps, the original is long gone.

Fuel pump is running, 40psi while cranking. Fresh fuel and filter.

Today I put in a brand new AGM battery. Tons of power. No dimming.

Tomorrow I will do the parts of the no-start check list I haven't done yet such as the crank sensor, but I've already changed the dizzy, checked for spark and checked for injector signal with a noid light. Would the injectors get a signal or would there be spark if the crank sensor was dead?

Talked the previous owner today....he said it was moved 6 years ago under it's own power with no issues. It has to be something simple.

Kevin
 
So now I'm looking everywhere online for a crank sensor (for my 92 and possible for this 89 as well) and NO ONE seems to have them in stock.

Where do you guys find this part?

Kevin
 
Can anyone confirm for me that if the shift light is NOT on during cranking then the crank sensor is ok and I should be looking at the cam sensor?

Could a cam sensor go bad just from sitting too long? Would the motor at least kick a little during cranking if it was the can sensor, or could it be completely dead from that?

Thanks folks

Kevin
 
Can anyone confirm for me that if the shift light is NOT on during cranking then the crank sensor is ok
If the shift light goes out while cranking, the crank sensor is working.

Could a cam sensor go bad just from sitting too long? Would the motor at least kick a little during cranking if it was the can sensor,
Not usually, but here's how to deal with a suspected bad cam sensor... just unplug it. It may take 3-4 tries to get it to start. Most of the time with a bad cam sensor, the tach will not operate.
 
If the shift light goes out while cranking, the crank sensor is working.

Not usually, but here's how to deal with a suspected bad cam sensor... just unplug it. It may take 3-4 tries to get it to start. Most of the time with a bad cam sensor, the tach will not operate.

Thanks. So if the car starts without the cam sensor connected, it's as simple as that i.e. it's the cam sensor? I know the ECM has a backup table for timing, and this is what it uses when there's no cam sensor signal...so if it runs without that means the current cam sensor is sending information but it's BAD information?

Just curious how it works...
 
See this thread for previous discussion: http://www.sccoa.com/forums/showthread.php?105167-bad-cam-sensor-causing-a-miss

You can save yourself a lot of head scratching, tail chasing, throwing parts at it, etc. if you go thru the no-start link first.


Agreed 100%. Believe me, I'm not one to randomly change parts hoping that I get lucky, and I've gone through parts of the no-start list but I haven't done the resistance tests yet.

Here's something interesting: This afternoon I started completely over and got as far as checking fuel pressure (38psi) and then spark. First I checked spark at the coil and got strong spark on all 6 terminals. Then I started checking each plug wire using a timing light, and get this....

ONLY THE WIRES ON THE DRIVERS SIDE ARE TRIGGERING THE TIMING LIGHT. NONE OF THE WIRES ON THE PASSENGER SIDE WILL TRIGGER THE LIGHT.

So I just replaced a MISSING ground cable on the passenger side (as mentioned above) hoping that maybe the head on that side wasn't grounded well but STILL no signal in the wires on the passenger side.

Tomorrow I'm going to pull the plugs and check for spark at the plug on each cylinder. Maybe it's as simple as the plugs being so old (and rusted?) that there's no strong spark on any cylinder.

Can anyone point me to a list of chassis grounds for the engine? Are there any ground straps on the cylinder heads?

If I can't solve this by replacing the plugs and wires then I'm going back to the beginning and doing the no-start list in full.


K
 
I'd like to share some of my experiences that I had in the past....1. The fuel pump harness above the fuel tank dry rotted,cracked,broke in pieces
2. The pink 30amp fuse that goes to the ECU was blown, that is under that black cover in the middle of the battery and wiper fluid reservoir.
These 2 things at different times cause my car not to start and run
 
Fuel pump connectors are good (just changed pump) and on MY SC at least, there isn't a fuse for the ECU in that fuse box under the hood. The fuse map on the back of the lid says *Except 3.8 SC

Again, I have fuel pressure, and the ECU is working.


Yesterday I changed plugs and wires. Same result in that I can pick up a signal with my timing light on the drivers side wires only. If I test the passenger side wires I get nothing, even right by the coil. Very odd. All six posts of the coil DO give spark when I put a tester on them.

I keep coming back to either weak spark ie bad coil but the coil has been swapped with a known good one, or bad grounding on the passenger side cylinder head causing the plugs on that side to not be grounded well enough. Sounds nuts to me but I can't come up with anything else right now.

Today I will go through the dis-no-start check list, in full this time.

Question for anyone who knows: Is it thermal paste or dilectric grease that's used on the DIS? I've seen both mentioned but they do very different things. If it's thermal paste....where have you found it in quantity? I've only ever seen small syringes of it for computer chips.

Thanks

K
 
About that paste....you're right. But this isn't about what each is typically spec'd for.

'dielectric': having the property of transmitting electric force without conduction; insulating.

...in the case of the DIS, the only electrical component at work between the DIS and the pedestal is the ground path from the corner lead(s) on the DIS, thru the mounting screws, and down into the pedestal. Otherwise, there is nothing electrical to insulate, and nothing to conduct.

As for the heat at work, the pedestal is hotter than the DIS when the engine is at temp. The compound's job is to prohibit hot spots on the DIS that can damage it's internals.

In my opinion, dielectric's basic properties can perform the job as needed. An exotic computer chip/heatsink compound will do the same thing, but is not required. What is required is a thin coat of something that can establish a thermal coupling between the two and remain stable at temps.

As a bit of a side note, it's clear Ford struggled with the design/location of the DIS as relates to heat as witnessed by it being moved to the fender in later years (same issue w/it's TFI predecessor). Owners of early model SCs are left to do the best they can, meaning whatever you do, never install a naked DIS.
 
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About that paste....you're right. But this isn't about what each is typically spec'd for.

'dielectric': having the property of transmitting electric force without conduction; insulating.

...in the case of the DIS, the only electrical component at work between the DIS and the pedestal is the ground path from the corner lead(s) on the DIS, thru the mounting screws, and down into the pedestal. Otherwise, there is nothing electrical to insulate, and nothing to conduct.

As for the heat at work, the pedestal is hotter than the DIS when the engine is at temp. The compound's job is to prohibit hot spots on the DIS that can damage it's internals.

In my opinion, dielectric's basic properties can perform the job as needed. An exotic computer chip/heatsink compound will do the same thing, but is not required. What is required is a thin coat of something that can establish a thermal coupling between the two and remain stable at temps.

As a bit of a side note, it's clear Ford struggled with the design/location of the DIS as relates to heat as witnessed by it being moved to the fender in later years (same issue w/it's TFI predecessor). Owners of early model SCs are left to do the best they can, meaning whatever you do, never install a naked DIS.



So the paste is PROTECTING the DIS from the engine's heat, not taking heat AWAY from it ie acting like a heat sink. Makes perfect sense. What about another material that insulates the DIS from conductance of heat through the bracket? Would that work?

An update on the original discussion:

I pulled the codes again and got 096 twice. "Secondary fuel pump circuit failure" or something like that. So I started tracing the fuel pump wiring and from what I can tell (please tell me I'm an idiot of I'm wrong), the 'priming' cycle of the fuel pump when you turn the key on is controlled directly by the ECM, but the 'run' funtion has to go through a relay first. So when starting, if the relay doesn't come on the car won't start even though you heard the pump run when you turned the key. Am I right?

So after starting to go through the fuel pump wiring, I found this black box in the trunk with a pretty good sized harness going to it.

What is it?

(stay with me guys...lol)

Kevin
 
So the paste is PROTECTING the DIS from the engine's heat, not taking heat AWAY from it ie acting like a heat sink. Makes perfect sense. What about another material that insulates the DIS from conductance of heat through the bracket?

I demonstrated via thermal imaging, in a previous thread, that the DIS is cooler than the pedestal: http://www.sccoa.com/forums/showthread.php?138649-DIS-relocate&p=1107435#post1107435 - that thread links to one where an owner lifted the DIS off the pedestal and another discussed relocating it. I've toyed with both ideas, but I don't see a chronic issue that prompts me to take such action...yet. Keep the ground path in mind if you decide to get creative,


So after starting to go through the fuel pump wiring, I found this black box in the trunk with a pretty good sized harness going to it.

What is it?

Does it have a reset button? If so, be sure to push on it, and see my earlier comment #6 above - http://www.sccoa.com/forums/showthr...deas-amp-things-to-test&p=1117089#post1117089
 
I demonstrated via thermal imaging, in a previous thread, that the DIS is cooler than the pedestal: http://www.sccoa.com/forums/showthread.php?138649-DIS-relocate&p=1107435#post1107435 - that thread links to one where an owner lifted the DIS off the pedestal and another discussed relocating it. I've toyed with both ideas, but I don't see a chronic issue that prompts me to take such action...yet. Keep the ground path in mind if you decide to get creative,




Does it have a reset button? If so, be sure to push on it, and see my earlier comment #6 above - http://www.sccoa.com/forums/showthr...deas-amp-things-to-test&p=1117089#post1117089


Thanks. I apologize for my laziness. I looked up the part number stamped on it and it's the keyless entry control module. Probably responsible for that pesky anti-theft system too. I have definitely checked the inertia switch...probably 5 times by now.

I changed the fuel pump relay with another one. No change. I disconnected the battery to clear the computer and rechecked. Now there's no code 096.

So after that I sprayed some carb cleaner into the intake to see if it would sputter at all. Nothing, so I'm leaning away from a fuel delivery issue being the problem.

Time to go through the DIS-nostart list now that I don't have any codes.

Can injectors get so gummed up after years of sitting that NONE of them will fire? Seems highly unlikely to me that they could ALL fail from sitting based on past experience resurrecting cars after sitting. They ARE getting signal according to the noid light.

To summarize:

Fuel pressure, check.
Spark, yes but only at the coil and after that it gets inconsistent even with new wires and plugs (see earlier post).
Injector signal, check.
Upshift light OFF during cranking, check.

Fresh fuel and filter
ECM swapped with another 89, no change
Cam sensor disconnected, still no start after 3-4 tries
Crank sensor swapped with another 89 (despite no upshift light), no change

All that's left (I think) is to check resistances and voltages in the DIS_nostart list.

K
 
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