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Discussion Starter #1
So been having a intermittent " CRANKS BUT WONT START" problem and we've been doing this test. Already cleaned the battery terminal posts, and ground post.

We tested from battery post [+ ] to alternator post [-].When the Car is running and when radiator cooling fan kicks on voltage drops by 8.\ on the ohm meter

Is this normal?
is this a sign of a battery/alternator that is going?

Alternator is original, battery im not sure but it tests at 13.8 volts

Another symptom when im driving occasionally the volt meter on my dashboard gauge wiggles back adn forth between the " r" and "m: in the "NORM" reading.

Today was at a red light and it started to sound like it was going to stall then it did, then had a crank but wouldn't start, then finally it started.

ignition coil bought in 2010, along with a distributor cap, also cleaned the IAC valve today looked good though.
 

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my voltage would drop when i was at a light. I had to clean my main body and engine grounds. I also replaced my ground cable. My never died thou just had a low idle when power would go down.
 

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You could test the grounds by checking continuity between various points. Such as battery neg to alt case and chassis grounds.

Another note, I had an electric radiator fan burn out and the symptoms right before it cooked were that the volt gauge would bounce around a little. Then it pegged over when it finally gave and grounded out.

If it only dies out at idle, i would suggest trying a different/new IAC. Also, clean the MAF (can't hurt).
 

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Discussion Starter #4 (Edited)
You could test the grounds by checking continuity between various points. Such as battery neg to alt case and chassis grounds.

Another note, I had an electric radiator fan burn out and the symptoms right before it cooked were that the volt gauge would bounce around a little. Then it pegged over when it finally gave and grounded out.

If it only dies out at idle, i would suggest trying a different/new IAC. Also, clean the MAF (can't hurt).
maybe it was the MAF that we cleaned, it had two springs on it? and we used a specific cleaner spray.

Any way to test the IAC itself to determine if its faulty? We had this problem before with this car and eventually replaced the ignition coil, distributor cap and IAC.Also were looking at the ignition control module [ICM] Does the PCV valve contribute to any of this?

Basically we ran through this test procedure at the link below, but it's now intermittent and every time it dies or has a "CRANK BUT WONT START" condition i can't do all the tests necessary.

http://easyautodiagnostics.com/ford_ign_fender/fender_mounted_module_1.php
 

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http://forums.tccoa.com/showthread.php?t=131472

This is my thread on the same issue. I believe mine was that the coil would get hot and fail. After it cooled, it ran fine. I ended up swapping out the coil for a new one. I'm not exactly sure that was the problem, but I haven't had it happen since.

http://forums.tccoa.com/showthread.php?t=140426

That is another thread of mine with similar issues. Lol. That time it was a bad connection for the IAC. I re-did the splice I had, and cleaned the terminals and she came to life.

I don't know of a way to test the IAC. I have a few of them I keep to swap around and try to diagnose.
 

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Discussion Starter #6 (Edited)
http://forums.tccoa.com/showthread.php?t=131472

This is my thread on the same issue. I believe mine was that the coil would get hot and fail. After it cooled, it ran fine. I ended up swapping out the coil for a new one. I'm not exactly sure that was the problem, but I haven't had it happen since.

http://forums.tccoa.com/showthread.php?t=140426

That is another thread of mine with similar issues. Lol. That time it was a bad connection for the IAC. I re-did the splice I had, and cleaned the terminals and she came to life.

I don't know of a way to test the IAC. I have a few of them I keep to swap around and try to diagnose.
How do i check the IAC wires?

TY, right the IAC is what i cleaned

- ignition coil? we replaced that and it does have splices in it.. may be it wiggles out and car stalls? or has the "crank but wont start" scenario

"Youve checked spark outside of the vehicle with a spark plug tester, or just a plug grounded out ?? Should have a nice blue spark, if its dull orange it could be weak from something in the ignition system but if spark is good"
read this in your thread, and when i spark test and the distributor its red/orange? Is it suppose to be blue/yellow?
 

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I would check, and possibly re-do any splice. I was using tap splices and that was not ideal.

You could try a used IAC and see what it does. There are 2 different ones though. 94-5 and 96-7. They are the same, except for the connector. One is square vs round or something. I have both pigtails spliced on, and that was where my problem was.
 

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Discussion Starter #8
we did replace the IAC a bit back in 2011 autozone called it a duralast" air bypass valve" is this the same as the IAC/MAF?

what about the spark plug tester color myth

should i run a few days with the IAC unplugged to see if it still stalls at idle/ has the crank but wont start ?
 

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Air bypass valve sounds like the IAC (mounts to the intake). The MAF is on the intake tube by the air filter.

I'm not sure on the spark issue. I just pulled one out and arc'd it on the alt bracket. As for color, I read that saying it needs to be blue-ish (hotter?) rather than orange-ish. I have no experience with that though.

I do know that when I tried to start the car WITHOUT the IAC plugged up, it would do exactly what your's is doing. It'd turn over, but not fire. That was the issue with my splice at the IAC. It was corroded, and the car didn't 'see' the IAC and would not start.
 

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If you can unplug the IAC and your symptoms do not change, then I would get a used IAC and try it. If it fixes it, then solved. If nothing changes with the different IAC you either have a problem somewhere else, or a bad used IAC also. I'd venture to guess the j/y part would be ok though.
 

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Discussion Starter #11
I was looking at the ignition coil and the negative terminal the wire was sort of out of the socket if that makes sense, like i had to shove it back in. i wonder if while driving its becoming loose/loosing connection and leading to this problem?

we also cleaned the distributor rotors where the spark is.

Then driving home it started stumbling? Like it was slipping or misfiring i dunno hard to describe.
 

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I'd also test the crank, knock, and cam sensors and wiring. I hope for yoursa keit 's not the cam sensor, it's part of the distributor and can't be replaced individually. You would have to replace the wholedistributor.
 

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Discussion Starter #15 (Edited)
So it stalled/died again while driving, got it into a gas station on momentum, but wheni got the tools i needed to test ICM etc of course it started back up...

We tested the fuel pressure gauge, and the PSI was only at 10 after a few "primes" and running.

Meaning i'd turn key to"on" position and i can hear the fuel pump activating.these values seem low? Would they relate to teh "crank but wont start issue" ?
ty

http://troubleshootmyvehicle.com/ford/4.6L-5.4L/how-to-test-the-fuel-pump-2

suppose to be 35 PSI?

I think i replaced the distributor 1-2 years ago, it may be under warranty
 

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Yah, being fuel starved WOULD make one not start.

I think it's time to drop the tank and replace the pump.

I'd highly suggest upgrading to a higher flow pump - even if you never EVER do any upgrades, 1) it'll flow more fuel helping to keep it cooler on the hot days and 2) you're set for when you drop in that 460cid 1,000 HP Honda Eater :diablo:

RwP
 

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Discussion Starter #17
Yah, being fuel starved WOULD make one not start.

I think it's time to drop the tank and replace the pump.

I'd highly suggest upgrading to a higher flow pump - even if you never EVER do any upgrades, 1) it'll flow more fuel helping to keep it cooler on the hot days and 2) you're set for when you drop in that 460cid 1,000 HP Honda Eater :diablo:

RwP
any tips on narrowing the fuel pump as the intermittent crank wont start problem? or is it solely the random stall problem?

also When it stalled last i put on the spark plug tester at the main distributor line and got no spark from the test light...
 

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I have an EVTM at home I can scan through this evening. I was told the pump either worked, or it didn't. I've never changed one out, but I've dropped the tank so many times that I wouldn't be scared to.

How old is the fuel filter? Another thing you may want to look at are the temp sensors. There are 2. One for the fan, and one for the computer. Maybe the one for the computer is bad/corroded? I just mentioned it because I have changed both of my sensors since I had this problem.

edit: I also thought that the 94/95 3.8L n/a didn't have a crank, knock, or cam sensor? I thought those came in 96 with OBD2?
 

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edit: I also thought that the 94/95 3.8L n/a didn't have a crank, knock, or cam sensor? I thought those came in 96 with OBD2?
94/95 3.8 NA California cars had a crank/cam sensor and DIS. 49 state cars had a distributor. Only the SC came with the knock sensor.
 

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Exactly! And the truck v6 got the knock sensor. So unless OP has a California car, he won't have those to worry about.
 
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