1990 3.8 wont start and im at my wits end!!!!

combatmedic

Registered User
1990 3.8 SC purchased last year from a friend who garaged it 11 years ago because because he started having problems and jumped through hoops to fix it to no avail. I took it off his hands for the low low price of five hundred bones, had it flatbedded to my place and the clean up began.
After doing the necessary in and outs and maint. she fired up and I was tooling down the road. Car ran great after working out some bugs then his original problem revisited upon me.
Here is a description of the symptoms: driving on freeway on night the car started to buck and lurch. Pulled over, shut her down, and after a few mins fired her back up. Car ran fine rest of the night. About a week later happened again on low speed surface road. Same deal... Let her rest fired back up and drove her home. Next day it wouldn't start. Would crack endlessly but wouldn't turn over and I parked her for the winter.
Well, spring has sprung and I decided to try and fir her up. Wishful thinking. No dice. After a bit of tinkering and considering it sat for so long I decided to get invasive.
New battery, fuel pressure sensor, cleaned and tested all injectors, new crank sensor, cam shaft sensor, plugs and wires, cleaned mass air flow sensor, O2sensors, checked inertia switch, new fuel filter, cleaned countless connectors, checked all fuses and relays, etc.....
Still nothing. Called mechanic friend who specializes in diagnosis and his work began be he was stumped. Eventually he pulled the ecm and plugged his diag comp into cor and he received an error message indicating no power to ecm or ecm not responding. He wanted to do an 88 pin flow test but that never happened. Have not seen him since.
So in short. Getting spark although I think its week. Getting fuel pressure. Wants to turn over but will not.
I was reading an earlier post about someone having same issue and most answers were leaning toward DIS which is the only thing I dint replace because previous owner had replaced it shortly before garaging her.
Any help would be truly appreciated. Hope I gave enough information.
 
Good evening

I would start with:

(1) The power distribution box (located in the engine bay driver side) for the Ignition blown fuses.

(2) Recheck the air gap between the crank senor and the harmonic balancer vane (used search). Speaking of balancer does it "wobble"? Pull/Push on the outer ring. If it does moves the balancer must be replaced.

(3) The DIS harness for chaffing/damaged. Take special note of the Cam sensor connector. Insure there is clearance between the connector and the supercharger belt. Inspect the DIS the four bolts for indication of rust. Clean or replace bolts if necessary. Inspect Bottom of the DIS for any indication of "heat sink". Re-apply if necessary.

(4) Check the negative battery cable where it is bolted to the front support. Make sure the small (16 GAUGE?) wire is securely attached from the front support to the cable itself.

(5) Check the ignition switch located in the steering column. Pull gently and check the switch has not separated.


Good Luck.
 
Hello Sam and thanks for your quick rrsponse.
I did fail to mention that while replacing crank sensor I discovered that the harmonic balance center bolt head had sheared off. I removed balancer and it checked out fine, cleaned everything up, remounted balancer and installed new factory center bolt, torqued to spec.
My mechanic buddy installed crank sensor and cam sensor at that time last year.
Checked out harness to DIS and it looks tip top. Removed DIS cleaned, reapplied dielectric grease, cleaned bolts and reinstalled. Negegtive cable; check! Ignition switch; check.... All fuses are good. Good strong spark detected.

Results: same issue. Won't start.

Anything I'm missing?
 
Reset the impact fuel shutoff in the trunk?

Inspected for burnt wires on the underside of the power control box?

12v at the battery while cranking?

Any dash lights on while cranking?

Fuel pump chatters, then stops after key on?

Have another computer to swap in?

Is the center bolt present in the harness connector at the computer (it's the ground)...?

See this troubleshooting walk thru if still no joy:
http://mnharms.com/tutorials/disnostart/
 
Good evening

I would take a second look at the harmonic balancer. When you removed the balancer did you inspect the key way slot in the balancer? How did the key way look on the crank shaft snout? Where there any cracks in the elastomer "rubber" section of the unit? Do search. If the balancer is original Ford or a replacement Dorman the sheared bolt is a warning of a pending failure (do search). The center bolt function is to prevent axial momentum from forcing the unit off of the crankshaft snout. I suspect the broken bolt and possible key way damage would allow the balancer to move both axially and radially at the same time causing the inner aluminum section to "deform". Removing and installing the original balancer and using a new bolt/washer could delay (during driving) the deformation but in time I believe eventually the bolt would shear again. Or worse.
Again take a second look at the balancer air gap. Check to see if there are "strike" marking on the balancer vanes or semi-circles "groves" on the crank sensor air gap section.

Good Luck.
 
I had an intermittent no start issue, replaced with a used dis and continued, replaced with a new dis and no issues since then...
 
I would replace the balancer if it were my SC. I have experienced the failure you described of the bolt breaking off...actually 3 times (I've owned roughly 30 SC's'). If you replace just the bolt the next failure will either be the entire balancer snapping off or potentially worse with damage to the crank. Again its happened to others and well I experienced it first hand myself as well.

The 2 replacement options that are suggested are:

http://www.summitracing.com/parts/pbb-pb1530n

(believe you have to extend 1 bolt hole slot on the pulley for this also)

or for more coin BHJ Balancer which is available from

www.supercoupeperformance.com or http://spinningwheels-sc.com/

Also to touch on the DIS - If you think it might be bad - you can take it to your local Advance or Auto Zone and they can test it for free...I usually test it repeatedly 4-5 times...when they get hot is usually when the issue shows up.

Oh and if the balancer is bad (which at this point I feel it is)...the Shift up light will stay on in the tach area of the cluster while cranking over.

-Tim
 
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Hello Sam and thanks for your quick rrsponse.
I did fail to mention that while replacing crank sensor I discovered that the harmonic balance center bolt head had sheared off. I removed balancer and it checked out fine, cleaned everything up, remounted balancer and installed new factory center bolt, torqued to spec.
My mechanic buddy installed crank sensor and cam sensor at that time last year.
Checked out harness to DIS and it looks tip top. Removed DIS cleaned, reapplied dielectric grease, cleaned bolts and reinstalled. Negegtive cable; check! Ignition switch; check.... All fuses are good. Good strong spark detected.

Results: same issue. Won't start.

Anything I'm missing?

check the position fo the crank sensor I had the same problem I had to use a feeler guage it took some time but I finaly got it
 
Try Dave

Dave Dalke is one of the best on these cars and he is only minutes away from you. Email him and set some time and $$ to have him look into the issues if you are still stumped.

Smitty
 
I would replace the balancer if it were my SC. I have experienced the failure you described of the bolt breaking off...actually 3 times (I've owned roughly 30 SC's'). If you replace just the bolt the next failure will either be the entire balancer snapping off or potentially worse with damage to the crank. Again its happened to others and well I experienced it first hand myself as well.

The 2 replacement options that are suggested are:

http://www.summitracing.com/parts/pbb-pb1530n

(believe you have to extend 1 bolt hole slot on the pulley for this also)

or for more coin BHJ Balancer which is available from

www.supercoupeperformance.com or http://spinningwheels-sc.com/

Also to touch on the DIS - If you think it might be bad - you can take it to your local Advance or Auto Zone and they can test it for free...I usually test it repeatedly 4-5 times...when they get hot is usually when the issue shows up.

Oh and if the balancer is bad (which at this point I feel it is)...the Shift up light will stay on in the tach area of the cluster while cranking over.

-Tim


i bought the fat 1. i didnt know about a thin 1 or i might have gotten that. https://www.supercoupeperformance.com/bhj-harmonic-balancer-sfi-approved-89-93-sc-xr7-540
 
DIS looked fine? Did you have it tested? Go get a new one and install it. The bucking happens after the car is warmed up that usually points to the DIS especially if it runs fine after it has cooled off. The HB should be replaced if the old bolt was broken. Never seen, heard or had one break just because......
 
I had the same problem turned out to be a worn timing belt. You can usually check it by using a timing light and varying the rpms at low rate to see if the timing wanders too much. My problem showed up at around 70,000 miles. My sc would stall and it would not start. By tapping the starter several times it would realign the timing and the care would then start until the next failure. Thplacid
 
I had the same problem turned out to be a worn timing belt. You can usually check it by using a timing light and varying the rpms at low rate to see if the timing wanders too much. My problem showed up at around 70,000 miles. My sc would stall and it would not start. By tapping the starter several times it would realign the timing and the care would then start until the next failure. Thplacid

If your SC has a timing belt I will buy it and you can name the price. Are you talking about a Turbo Coupe?
 
First replace balancer with a powerbond from Orielly they work great! all you have to do is elongate one hole in the crank pulley.

Replace DIS i've seen them test good and be bad. DIS is likely youre problem
 
timing belt ?

all those years of replacing the timing belts on my other cars and all I had to do was whack the starter to adjust it..
 
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