No Spark, and the definition of insanity

TRU 5.0

New Member
Sep 30, 2007
11
0
1
Nazareth, PA
Greeting all,

I want to apologize in advance for the lenght of this post, but I want to be thorough. Having spent a number of months trolling this site, it's time to seek some assistance to my current frustration. I bought my 90 LX 5.0 approximately 6 months ago (from the original owner) with a few issues, but resolved them fairly quickly ( dirty MAF, bad battery cables, TFI and stator). I cleaned the MAF, bought a new MSD distributor, and replaced the battery cables. Car ran strong thereafter with no further problems. 2 weeks ago, we performed some improvements to the drivetrain (shown below), and took the car for dyno testing at a local shop. During the test, the TFI ( on the MSD 8456 distributor) apparently failed, and was replaced with a stock one. We finished the tune, and I left. About 5 miles down the road, the car shut off - no spark. I have used jrichker's checklist, among other information, and have this to offer:

Coil is getting 12V, as are terminals 3 & 4 on the TFI
(Another) New MSD distributor and coil ( both swapped during current diagnosis)
Verified coil wire resistance
Fuel Pump is providing 39 LB pressure at the rail
All fusible links on starter solenoid are intact ( tested with a voltage meter)
Verified ground wires are connected to back of block
Swapped computer into another 5.0, and his car started with my ECU.
12V on the red wire going to injectors/MAF
We also verified continuity from the TFI to the ECU
TPS is set at .98
Battery cables are new, 2 gauge - battery is fully charged at 12.62V

I have not checked injector pulse, but will pick up a noid light today to verify. It appears they are not pulsing, as I don't smell fuel and the plugs look fairly dry.
We spent the better part of the last two days checking everything (twice, three times), hence, my title - The definition of insanity is doing the same thing and expecting different results - I am out of ideas. :shrug:

Thanks for your assistance.
 
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Iam just taking a stab in the dark but clean the 10 pin connectors and spread the male terminals. You have done every thing I would of thought to say. Make sure you still have a good ground to the 10 pin connectors the orange wire that goes to the back of the manifold on the driver side. The only other thing that triggers injector puls is the stator in the dist. Whick most people including my self I think they are junk "my opion" and run a known good stock dist and make sure you have it set at tdc.
 
Do you have a spare dizzy to put in there? I would be wondering about the PIP (they seem to be, ahem, problematic with some aftermarket dizzies). Once you get your noid light, you'll know. If it flashes, the PIP should be ok.

If playing with TFI's, be sure to keep the same color TFI as yours had stock. There's a push-start TFI (early aero foxes) and a CCD TFI (later aero foxes). They bolt right up but are not interchangable. Note that I don't see this as an issue for you - just something to remember if swapping dizzies around.

Once you know what the injectors are doing, that will help.

Good luck and bump.
 
A trip to the JY netted a marginal dizzy ( not many choices), but I got it installed and the car started. Noid light flashed before it fired up, telling me the PIP in the previously installed, brand new MSD was N/G. The car still doesn't run properly ( I question the integrity of the JY dizzy), but it's running.

I have to question why the car has 'eaten' four PIP's in a six month period. The factory one, one I rebuilt thereafter with all brand new parts ( non-Ford, however), the first MSD which lasted 5 months, and now this mess.

Thanks for the push to get another distributor - It was my feeling the PIP was bad, but it seemed virtually impossible that a brand new $275 high-performance part could be out-of-the-box bad. Live and learn, so they say.....

:SNSign:
 
If it were not for all the folks having issues with the PIPs in aftermarket dizzies (guys are reportedly losing them after as little as 200 miles), I'd have been skeptical too.

A bad bushing in the OEM dizzy could have taken out the OEM and subsequent PIPs. Then the aftermarket dizzy had an issue all its own.

Otherwise heat is what eats them. Their insulation is a known weak point, which is why you can sometimes bring them back to life (for diagnostics) with wiggle testing on the harness.