New engine - but is it getting fuel?

[Gary Lewis]

Cool!  How 'bout taking pics while doing it?

[sgauvry]

I can manage that!

[NotEnoughTrucks]

Yes, that is the tank selector switch and it sure is interesting in that you have the 5 pin version.

I did make that promised trip to my old cab last weekend. Still grumbling about the weather. trudging through 1/4 mile of snow when we are supposed to be up to our knees in mud and spring runoff!

Anyways, my truck has the 6 pin wiring.



Views of each side and the face.







The harness runs into the wire bundle on the right side of the truck. You can also see the inertia switch in this picture.



Now, it's my understanding that the 6 pin switch is used with the in tank pumps and EFI while the 5 pin switch is used with the motorized tank switching valve. Is it possible that your truck was previously converted to EFI? Sure would make sense of some of the issues you have found.

[85lebaront2]

Remember his truck is a 1985.5 and was a factory change in mid year to EFI and everything about those seems to be unique to that model.

[NotEnoughTrucks]

Hmmm.

Steve, you mentioned your wiring more closely resembles the 7.5l wiring on p102 of the EVTM. I'll presume you also do not have the dual tank switch in the heater control, but you were able to locate the plug, which is wired for 5 pins.

So, I'll presume your truck was a factory single tank truck and being one of those 85.5 unicorns, Ford may have simply used a cab harness from a non EFI truck? That 5 pin switch does a polarity reversal trick for the fuel selector valve instead of the more conventional DPDT arrangement of the 6 position switch found in a dual tank EFI truck.

At any rate, I have not personally seen a single tank EFI bullnose truck. I have seen a few bricknose with single tank and they always had the wiring for dual tank, with a plug in jumper in place of the tank switch, permanently configuring the wiring for the front tank. One application I saw was an F350 cab and chassis, the other an F150 single tank pickup.

Another one of life's mysteries!

[sgauvry]

Wow! This gets more interesting with each post!!

Hard to say what this truck was at the beginning. The wiring may be a original, or not.  Hard to say.

However, I can say she cranks and she's getting plenty of fuel. Had three wires that were not connecting correctly.  Resolved that and both fuel pumps are working as they should.

Now, it's a starting problem. Will be doing diagnostics on the coil checking primary and secondary resistance, spark, and so forth. Hope to get that done today.

[Gary Lewis]

As Jim says, progress is good!  You are nigh unto having it running again.  

[sgauvry]

We will see, but I think you are right!

Coil has 12.4 volts going to it.  That is good.

Primary Resistance on coil is only .2.  Not good.

Secondary resistance on coil is 7.8.  That is good.

Will do a switching signal test when I am able, as well as the other coil tests, and check the PIP.  

Something's not right somewhere, just have to track it down.  

[85lebaront2]

Steve according to my AllData, Primary windings 0.3-1.0 ohms, Secondary windings 8000-11,500 ohms.
If you want, I have an extra here I can measure for you.

[sgauvry]

Thanks, Bill!  Coil is likely bad, so I ordered a new one.  However, there are other coil related tests I want to do as well as a TFI module and PIP test. Want to make sure all is working as it should.

[sgauvry]

Today I ran tests to the Ignition Control Module (TFI) using my voltmeter.  

Here's the results.  
1.  Tested for power to the module = 12+v
2. Tested the ground circuit = 12+v
3. Tested for Ignition Coil Switching = Voltmeter switched from a reading of volts to no volts back and forth as engine was cranking.  This means the ignition control module is triggering the coil as it should.

I know my ignition control module is working and the connections I made are good.

My crank-but-no-start situation has GOT to be the coil.  If you good gents think of something else I should test, please share.

Thanks!!

[Gary Lewis]

Pull the coil/distributor wire and place it close to a good ground.  When you crank the engine you should see a good white or blue spark.  If so, the coil is good.

[sgauvry]

Hi Gary -

Yes, I did that, but I had a reason to make this more complicated.
I extended the wiring to the ignition control module (TFI) because I want to mount the TFI remotely so as to preserve it's life.  Gets too hot mounted to the distributor and that heat is cause for TFI failure.  

So I wanted to (1), check that my TFI module is still good, and (2), ensure all of my new connections are solid.

Passed on both counts and also served as another indicator that the coil is bad.  

Prior coil testing involved primary and secondary resistance.  Overkill, maybe, or possibly showing off newly acquired skills.  

Steve

[85lebaront2]

Steve, is Gary that much of a bad influence? He certainly likes to complicate things just like my former department manager, his initials are CES and several of us decided it stood for Complicate Everything Snyder.

[Gary Lewis]

Do you read lips?