No start

[Jim Wright]

So I have a 1989 ford ranger 2.9. Been fighting this problem off and on for 6 months. Took it to a local mechanic and the next day he called and said come and get it. Said he could not spend any more time on it. Charged me 140.00 bucks and said he couldn't figure out. So here is what is going on. Injectors are pulsing but putting out minimal gas. Installed new injectors, no charge. Have 38 lbs of fuel pressure at fuel rail. Can jumper 12 volts to injectors and they spray just fine. Have 12 volts at connector to injectors so I think the problem is the ground from the ecm that grounds injectors. Have checked and double check all grounds on truck and ecm. I hookup a multimeter to battery positive and the ground side of injector connection and turn motor over with remote starter and it shows 3 to 4 volts when pulsing. Was wondering if bad ecm. I know that the power ground floats in ecm. If that ground is bad would that affect the grounds to injector also. I am completely out of ideas. Thanks jim

 

[RonD]

First things first

Crank the engine over a few times and pull out any easy to get at spark plug
Tip should be WET with fuel, light that fuel with a match/lighter, should burn fast and easy
If not, it ain't fuel in the gas tank, drain it, put in fresh gasoline(5% or 10% ethanol fuel is best, you have water in the tank, ethanol clears out the water)

If tip is DRY then yes, injectors are not opening as they should on a Cold Engine(choked), or not at all, because if they were opening, even a limited time, engine would "fire" after a few cranks, maybe not start but "fire"

If tip is WET and burned easy then you have a spark issue, or compression
You can test compression at this point but on a 2.9l it would be a long shot with mechanical chain setup

On the dash is the CEL(check engine light), 1989 should have that
Watch the CEL
CEL should come on with key on, means computer has powered up
Crank engine, CEL should go OFF as soon as engine is spinning, that means computer is getting a good Timing Pulse from TFI module/Distributor
If CEL stays on or goes off and on then bad or no timing signal from spark system

TFI modules do "go bad", usually the first stop

If you want to test spark there really is only one way
Spray fuel into the engine manually, 50/50 test
Gasoline, ether, carb cleaner, ect....
Crank engine
If it starts, runs and stalls then fuel delivery is indeed the issue
If it doesn't start/fire then no spark or no spark at the right time
50/50 instant results no guessing where to look next

If 50/50 gets engine to start then pull the computer out and open it up
There will 2 or 3 barrel(radial) capacitors on the circuit board, check them but just plan on replacing them, under $5 fix, unless you plan on swapping computers

 

[rusty ol ranger]

Just curious...


Have you replaced the fuel filter?

Good pressure doesnt always mean good volume

 

[Jim Wright]

Thanks for comeback. Did the 50/50 test starts right up and runs till out of fuel. I had a old upper intake so I installed fuel rail onto it so I could see what the heck was going on with the injectors. Have pic as attachment. Seems that with injectors connected very little fuel is coming out even though I have pulse. If I remove injector harness and hook up 12 volts from battery to injector it has normal spray. I recently replaced distributor and ignition control module also fuel filter. If I disconnect ignition control connector and check

ground at connector I only have 7 volts. Not sure what voltage I should there. Thanks jim

 

[RonD]

If engine starts and runs with 50/50 test then spark is strong and timed close enough, lol

So issue is solely computer and fuel delivery

Did you check spark plug tip?
WET or DRY
If WET did it burn easily?

+1 on fuel filter

 

[rusty ol ranger]

It could be a wiring issue as well.

I think you should have 12v there...but im not 100% sure

 

[Jim Wright]

If engine starts and runs with 50/50 test then spark is strong and timed close enough, lol

So issue is solely computer and fuel delivery

Did you check spark plug tip?
WET or DRY
If WET did it burn easily?

+1 on fuel filter

So why I suspected fuel injector spray was because after cranking with good fuel pressure and pulse. I would check plugs and they were dry. Also checked flow of gas coming from tank and had good flow to fuel rail. Over time i have had three mobile mechanics plus a shop troubleshoot the problem and all three gave me different solutions to fix the problem, after doing the fixes they recommended still having same problem. My theory is if these guys don't get a code from a obdll there kinda lost. Because I have eliminated all the suspected causes guess I am looking at new ecm. Thank you for your reply and if you can think of anything else I could try please reply.

 

[RonD]

Just pull the ECM(PCM) and open it up
Look at the barrel(radial) capacitors, there are only 2 or 3

Do you have a CEL(check engine light)
Does it come on and then go OFF when cranking engine?

 

[Jim Wright]

Just pull the ECM(PCM) and open it up
Look at the barrel(radial) capacitors, there are only 2 or 3

Do you have a CEL(check engine light)
Does it come on and then go OFF when cranking engine?

Check engine light lights up and go's off when engine cranking. Will check inside of ecm and see if anything is noticeable. Thank you for replies. Jim

 

[Cees Klumper]

Replacement ECUs can be had for about $100-150 on Ebay etc. I recommend you get a spare one to try out. Besides replacing those capacitors as recommended in your current one. A bad ECU can definitely cause odd issues.