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starts when cold, runs rough till warm, then dies won't start again for at least a da

cencaligrl

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My credo
she's ugly, but, there ain't nothin' wrong with the radio.
So, I am stuck... My truck ( '86 Ranger 2.9 L) has a fuel problem. We have troubleshot as far as we can.
For starters, you should know what she is doing. I recently moved back to CA from CO where I bought the truck. She ran fine for the 1st 6 weeks or so before she started running rough. On my last sojourn into town (30 miles away), she died as soon as I stopped. She wouldn't start again for anything. Had her towed home, where she has sat for the last 2 months or so while we troubleshoot the problem. She starts when VERY cold (ie., after she sits for 24 hours). She runs rough the whole time, getting progressively worse till she's warmed up. Then she dies and WILL NOT restart for at least 12 hours, and only starts then with the gas pedal floored.

Here's what we've done so far. New fuel filter (below driver's door on the frame rail; new fuel pump, new fuel pressure regulator, new fuel pump relay (the relay that's located on the passenger side front fender next to the air filter box; removed the throttle body and cleaned all parts with high quality parts cleaner; and cleaned the air intake.

Where do I go from here? I was told to check the cat and replace the injectors, but, they were just replaced a few months before I bought her...
By the way, I call her a she because she is a temperamental as a woman.
 
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RonD

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Welcome to TRS

Since you replaced the fuel system parts I assume when you added gas manually to intake the engine started OK?

Or did you replace those specific parts because...........??

First, a few points
Cold engines need more fuel, so can run richer, as engine warms up it will die if too rich

Cold electrics work better than warm electrics, failing coil and/or TFI module can become intermittent as they warm up.
Good read and testing info here: http://www.therangerstation.com/tech_library/TFI_Diagnostic.shtml

A collapsed muffler blocks exhaust flow so engine chokes out, but this is not a cold warm issue, as RPMs increase engine runs worse cold or warm.

As to your problem the "gas pedal to the floor" may be a clue.

All fuel injection computers have a "clear flooded engine" mode.
To get this you:
Turn on key
Press gas pedal to the floor and hold it down
Crank engine(activate starter motor)

That's "clear flooded engine" mode
"Press gas pedal to the floor and hold it down"<< this turns OFF all the fuel injectors but leaves spark on

If you crank engine with gas pedal to the floor and it fires, even a little, you have a leaking fuel injector.
Leaving the engine sitting for a while allows gas in intake to evaporate so you can restart it, so it isn't the cold/warm its the time.

To test this theory, simply do the "clear flooded engine" test, but because of the possible leak I would turn key on count to 3 then turn key off, then turn key on count to 3 then off again, now turn key on and start the test.
This on and off primes the fuel system which would be at 0 pressure if there was a leak.

If engine fires you have a leak, leave your foot down on the gas pedal, do not let it up even a little or injectors will start opening.

Now there could be a wiring issue instead of a leak.
'86 computer operates the fuel injectors by grounding them, and there are only 2 wires from computer to 6 fuel injectors so it grounds 3 injectors at the same time, this is called Batch Fire fuel injection.

When you turn the key on all 6 injectors get 12volts but are not grounded so stay closed, if one of their wires had bad insulation and was touching a metal part, then 3 injectors would open, flooding the engine.
Each injector will have a Red wire, that's the 12v wire
Ground wires to computer will be Green/white and Tan/red, check if these are grounded, they shouldn't be, if one is then move wiring harness around and see if you can find the problem.
 

kimcrwbr1

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Pull the TFI module off of the distributor and have your part store test it three times. If it fails get a high quality one, in general if you buy cheap thats what you get. be sure and put the heat sink grease on the module when you install it.
 

Earl43P

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Your truck also has TWO fuel pumps.
One on the driver side frame rail, high pressure.
Other is in the tank, it lifts the fuel for the HP pump to deliver.
Borrowing a fuel pressure tester from an auto parts store should help you figure out whether they are both working.

If you disconnected the frame one, you will see about 5psi. Reconnect it and see 35.

I'd also check for spark, as advised.
 

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