No spark when cranking. 89 STX 2.9L

[Maui-sprint]

Truck is a 1989 stx 2.9 manual trans. Just got truck. Wires and harnesses are in poor shape but was able to get it running few months ago then it sat. Go back to it and now wont start. On some tries it will begin to idle then nothing. Im getting 12V at coil red lead. Ground tested good. Not sure how to test the signal wire at coil (green/yellow stripe)...? Hook a spark tester between coil and distributor: tester sparks once when you start cranking then nothing until you stop cranking and then it sparks twice. Any ideas what this should point to?

 

[lil_Blue_Ford]

Almost sounds like the TFI module is toasted. Probably be worth checking the cap and rotor, I’ve had them end up broken/messed up before. If they look good, I would pull the TFI module off the distributor, some auto parts stores can still test them, make sure the test gets run a couple times in a row so the module gets warm to the touch and have them test the new module the same way, I have seen them fail out of the box before

If it is neither of those, then we move on to other things, but that’s where I’d probably start.

 

[Maui-sprint]

Ok will do. Hopefully that does the trick. Manufacture date of truck is jan 89. Will any 2.9 TFI work for my rig? Or does it have to be a specific date code?

 

[RonD]

Needs to be Grey color TFI module, not Black
4 types seen here: https://www.stangnet.com/mustang-forums/attachments/tfi_5-0_comparison-gif.250293/
You need the 2nd one down


Sitting a few months?

Gasoline doesn't last very long, the combustible chemicals degrade over time especially in warmer climates
Also water and gasoline can't mix, and all gasoline has some water in it
Water is heavier than gasoline, so when it sits in the gas tank for a few months all the water collects at the bottom of the tank
Fuel pump pulls in fuel from the bottom of the tank.....................so all the water FIRST


Try 50/50 test
Spray fresh fuel into the engine directly to see if you can keep it running
If so then add some octane Boost and fresh gas 5-10% ethanol to tank

 

[lil_Blue_Ford]

Ok will do. Hopefully that does the trick. Manufacture date of truck is jan 89. Will any 2.9 TFI work for my rig? Or does it have to be a specific date code?

I believe any Ranger/Bronco II TFI for a 2.9 will work. Don’t quote me on it though, been awhile since I had such problems since presently my 2.9 equipped B2 has been down for a few years and the only other TFI equipped vehicles I have are both full size with the remote mount TFI modules.

They sell a tool to get the bolts out, it’s either a torx bit or a thin wall socket. I’ve done them without the tool before but now I have two of the tools, one lives in my F-150 because it’s managed to toast a couple modules over the years despite being remote mounted. The tool has both. The module has an electrical connector and also three blades that plug up into the distributor. Pain in the neck. When I get back to fixing my one 2.9, I’m going to do the conversion to a remote mount.

 

[Maui-sprint]

Thanks guys. I just picked one up from auto parts store. Matches the one Ron D said to get. I used a deep 5.5 mm socket to remove. Was tight but worked. Motor will not run when spraying in quik start. Spark tester shows a spark initially upon cranking (1sec) then nothing until you stop cranking (another two sparks). I installed a new coil, checked cap/rotor looked good, new plugs, replaced all the crappy harnesses with decent good condition ones. Still nada. Im on way home with new TFI module. Will let you know how i make out.

 

[Maui-sprint]

Put in the new TFI module. Same thing. A quick spark upon initial crank-no spark while cranking-two sparks when stop cranking. TFI module passed resistance test. Any ideas? I just need a temp fix so i can get it moved onto and off the ship. Once it gets to hawaii im making a boat anchor out of this motor. What about ignition switch? It appears kind of sticky. Any way i can bypass it?

 

[lil_Blue_Ford]

If it’s cranking, theoretically it’s not the ignition switch. Really kinda suspected the TFI from the weird spark pattern. Unless the new coil is DOA, rare, but I had it happen, after I painted it too. But if it’s throwing some spark, you would think that would indicate it works…

 

[alwaysFlOoReD]

I'm not good with electric. That said, isn't there a start wire that can that can be misplaced so that there is no spark except at beginning and end of crank?
@Uncle Gump
@RonD

 

[Maui-sprint]

Actually i left a part out. The first time i tried cranking motor with new TFI module was the best it performed yet. I was able to rev it and keep in running for about 10 seconds befor it quit and went back to the usual. Maybe a short or ground fried the TFI? Is there a way to test all the connections at TFI connector?

 

[Uncle Gump]

In some vehicles there is a bypass wire to feed the coil during crank. Because the coil feed wire is resistive to reduce the the voltage to the coil running.

Edit... I believe that was pointed and duraspark ignitions though

 

[Maui-sprint]

Update. Put new ignition switch in and made no difference. Except now no fuel pressure as well. Throughout this whole ordeal the fuel press has been intermittent on/off. If I jump the relay connector pump works every time. But its hit or miss when cranking with key. So intermittent fuel pressure and spark-no spark-end spark. Has to be a short or something grounding. Open to ideas. My time is running out

 

[RonD]

'Hot wire' the coil, just to test, put jumper wire from battery positive to coil +, leave other coil wires connected
Try to start

What you described it as "A quick spark upon initial crank-no spark while cranking-two sparks when stop cranking " this is a "classic" symptom of START wire issue
There are TWO separate 12v wires from ignition switch that power Spark, one powers spark with key on, the other powers Spark with key in START, the 12v in ON is CUT OFF when key is turned to START, so if no 12v on that START wire then no spark
With key ON coil is powered up, so will spark one time if power is cut, that's how coils are suppose to work
When you stop trying to start the engine key comes back to ON and engine is still turning so a couple more sparks, but engine is turning too slow to start

This two separate wire system was originally used with a Resistor Block or a Resistor Wire so coils didn't burn out
The other "classic" symptom for this setup was engine would start but then die as soon key came back to ON, so START wire has 12v but ON wire doesn't



Fuel pump only runs for 2 seconds with Key on, then won't start again until RPMs are above 400
Cranking speed is 200rpms

But each time you turn key OFF and then back ON it will run 2 seconds again, so you can repeat key on and off to build up pressure

I would try Jumper wire on Fuel Pump test port
It is on the OBD1 connector in engine bay

Look here: https://www.therangerstation.com/tech/testing-eec-iv-equipped-engines/
2nd drawing
OBD1 connector, it has Fuel Pump slot labelled
Computer Grounds the fuel pump relay to activate it, for those 2 second or full time after engine is above 400rpm
This slot is that ground wire from computer to FP Relay
So use a Jumper wire in that slot and to a Ground(battery negative)
With Key ON FP relay should "click" closed and fuel pump should come on full time
You can pull the jumper out of slot and put it back in, with key still on, and you should here relay "click" and fuel pump come on each time its grounded
And try to start engine with jumper inplace, doesn't hurt anything

This tests if FP relay is working as it should

And you can use a test light in the slot and to battery positive, light should come on for 2 seconds each time key is turned on, this tests if computer is grounding FP relay as it should


Just FYI, the 2 second thing is for safety, in an accident/rollover any electric fuel pump will keep on pumping out fuel if battery is still connected
If a fuel line should break that would be a VERY VERY BAD THING, lol
But if a fuel line broke then engine would STALL and computer would shut off power to fuel pump once RPMs were under 400
So a safety thing

 

[Uncle Gump]

This two separate wire system was originally used with a Resistor Block or a Resistor Wire so coils didn't burn out
The other "classic" symptom for this setup was engine would start but then die as soon key came back to ON, so START wire has 12v but ON wire doesn't

That system was used not to prevent the ignition coil from burning out.... but to protect the low side of ignition coil driver circuit (points, duraspark or earlier electronic ignition controllers) from over heating and burning out. The bypass wire or ballast resistor block was necessary because during crank... the battery voltage would drop... and if coil power was low (because engine was cranking) and it was supplied through the additional resistance.... there was not enough voltage to create a hot enough spark to start the engine. So the bypass circuit was used.

You should be able to try two jumper wires.... one to ignition coil B+ and another to fuel pump and see if it will start and run. If it does then you will have to trace down the problem in the wiring system that is in "poor shape".

 

[Maui-sprint]

Good stuff RonD. Will try jumpers to coil + for spark and to OBD1 for fuel pump. Hopefully this works.