need some info on ford 5.0 no spark problem

mywhite89

mywhite89

Registered User
Between getting my cars ready for the shootout, my buddy dumped off his 95 5.0 stang to me to figure out. Drive for about 30 minutes the car just dies. Cranks but wont restart.

I took it for a drive last night, just as I was getting close to home it died. I coasted the beast into my driveway. How much luckier can you get!

Anyways, no spark coming from the coil. I test power and ground at the two prong connector going to the coil. I lit up a halogen light with it, so seems to be good voltage and current to coil. Anything you guys can think of that I should check into further?

My buddy replaced the coil a while ago trying to track this problem, I don't see anything else it could be.

Only other information I have, when I had my test light hooked up to that connector the light flickered quickly while cranking. I assume this is just the signal which comes from the ground wire. When I used the battery as my ground reference the light stayed on constant. There is no flickering with a halogen bulb connected, probably doesn't respond as quick as my led test light.

Chris
 
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I has a silly question. Why would you get a constant 12V across the coil all the time except when it's cranking?

I'd check the ignition module (known to fail on all the dizzy Fords) and make sure that you're getting a good signal TO the coil.

Dunno where it is on the 1994 Mustang, but one of the improvements they made to the Cougar 5.0HO was to move it to up by the airbox ... so I'd make sure it wasn't there at the dizzy.

RwP
 
RalphP said:
I has a silly question. Why would you get a constant 12V across the coil all the time except when it's cranking?

I'd check the ignition module (known to fail on all the dizzy Fords) and make sure that you're getting a good signal TO the coil.

Dunno where it is on the 1994 Mustang, but one of the improvements they made to the Cougar 5.0HO was to move it to up by the airbox ... so I'd make sure it wasn't there at the dizzy.

RwP
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Sorry I meant I get voltage to the coil when cranking. I just don't see any spark from it at all.

He has replaced the TFI and relocated it, so he must have done a little more homework than I have done. Its a low budget operation, so he may have installed a used one or something.

Well, I figured if I had voltage to the coil but no output to the wire it would have to be the coil.
Chris
 
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mywhite89 said:
Sorry I meant I get voltage to the coil when cranking. I just don't see any spark from it at all.

He has replaced the TFI and relocated it, so he must have done a little more homework than I have done. Its a low budget operation, so he may have installed a used one or something.

Well, I figured if I had voltage to the coil but no output to the wire it would have to be the coil.
Chris
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Not necessarily. The TFI switches the ground side, so you'll have 12V on the hot side all the time.

Which explains what you said - across the coil, you'd usually see nothing except during a spark event. From either side to ground, you'd see voltage (it'd drop on the low side).

Used TFIs are also tricky since they can also be dead.

This unit DOES have a dizzy on it, right? 94 GT should be the same motor as the 91-93 MN12s.

I'd make sure that the dizzy isn't too far off - pop the cap off, hand crank the motor over to about TDC, and make sure the rotor's either pointing to Cylinder 1 or 180* out (depends on if you were on compression or exhaust on #1 cylinder).

There's some tests you can make on the reluctor and on the TFI both with a good multimeter.

If you want, I'll see if I can dig them out (i.e., scan them out of my 1991 service manual).

RwP
 
So it flickers when you crank it? If so, replace the coil. The flickering is the on/off caused by the open closed signal from the star wheel (stator) inside of the dist. If he has already replaced the module, why did he not do the stator at the same time? Ask any Ford tech at a shop and they ALWAYS do both since they go out within a week of getting back together. BTW, what color wire are you testing? Both?

SWS
 
seawalkersee said:
So it flickers when you crank it? If so, replace the coil. The flickering is the on/off caused by the open closed signal from the star wheel (stator) inside of the dist. If he has already replaced the module, why did he not do the stator at the same time? Ask any Ford tech at a shop and they ALWAYS do both since they go out within a week of getting back together. BTW, what color wire are you testing? Both?

SWS
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So the stator sends a signal to the ignition module then the module back to the coil? I tested both wires in the connector using the 2 red wires that come into 1 teminal at the connector as my positive and the other single wire which I believe is the (pip) one as my ground. In that form, my test light flickers but the car wont start.
 
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I would say the coil is bad then. If you have no light or a solid light it is pip and/or tach. If it flickers, it is working. Not to say there is not an intermitant problem, but I bet if you get (remember those are e-coils and conv ones do not work) a good coil and replace it when it goes, I bet it will be fixed.
 
seawalkersee said:
I would say the coil is bad then. If you have no light or a solid light it is pip and/or tach. If it flickers, it is working. Not to say there is not an intermitant problem, but I bet if you get (remember those are e-coils and conv ones do not work) a good coil and replace it when it goes, I bet it will be fixed.
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Thats what I was thinking, cheap and easy replacement. I might just have him drive the thing, when it quits on him he can replace it on the side of the road and see what happens. If it was me, I would probably buy a module also and keep the tools on board just in case since those are a big problem as well. It is an autozone coil, i've just never been a fan of autozone parts anyways.

chrs
 
I am going to go with a bad distributor. The distributors on the 94/95 5.0's are notorious for going out. The pickup unit goes south and causes all kinds of intermittent issues. I would also agree that tfi modules are also terrible but when I worked at ford I installed more dead distributors in the 94-95 5.0's than tfi's.
 
If he has a flashing light on the coil power, and nothing out, how could it be the dist? Like if you flip a light switch, and the light does not come on, but you have power to the socket. Do you replace the switch or the bulb?

As far as vatozone electronics, Im out. If the TFI is not ford and the coil is not ford, you have wasted your time and he has wasted his money. Those will cause more problems than they fix. The ONLY way I use those stores for electronics is for cheapie stuff on weekends to get me through.

I replaced the DIS on my 93 on a monday because Ford could not get it 'till Wednesday. Tuesday, I took it back because it lasted 45 min or so, and then cut out worse than the burned factroy one. Put the factory one back on, limped it to a bone yard, and picked up another Ford one until I got the new one a day later. Had to have it.

SWS
 
Well I guess we'll find out soon enough, he bought another cheap autozone coil. I told him to keep his tools handy and as soon as that thing died again to stick the new part on by the side of the road. That will tell us if the coil is the problem. Hopefully the new cheapo part he bought doesn't fail. There is a reason sometimes when fords part is 50 bucks and aftermarket is 22.

Chris
 
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seawalkersee said:
If he has a flashing light on the coil power, and nothing out, how could it be the dist? Like if you flip a light switch, and the light does not come on, but you have power to the socket. Do you replace the switch or the bulb?

SWS
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I hear you but these distributors are intermittent when they go and do strange things when hot and spinning much faster than cranking speed. Only time will tell.
 
maybe im just lucky but i've never had a crank trigger cam sensor or dis module from autozone ever fail on me, nor an alternator

i did have an autozone starter fail on me once in a chevy beretta but other than that my dealings with duralast have lasted durably lol
 
The problem with the dist would be the stator if it is an electronic/signal problem. New Ford one is probably 1/4 the price of the dist. Not discounting this, but if the signal to the coil is right, and there is no fire, the coil is the problem.

If you have never had any problems with aftermarket parts, knock on wood. When I worked in the dealership, I had a good amount of comebacks because of junk electrical parts. Ran Orilleys out of starters in one day for a 2.9 ranger.

SWS
 
Ok distributor was the solution! Kudos to the genius' that said so!:D. Word to the wise, check for rust on the pick-up inside the distributor.
Thanks,
Chris
 
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