Running Rough!

Mark Klein · Dec 20, 2016

I just bought a 1999 Ranger 3.0l Flex Fuel. It has sat for at least 1 1/2 years. Previous owner claims it ran great. It runs very rough - smooths out a bit - then rough again... Changed plugs. They were a little black/oily? It has 199K miles. Pulled plug wires one at a time. Each cylinder responded the same. No distinct cylinder not firing. The spark was only slightly blue/straw although it would arc about 3/4". Would a weak coil cause the roughness? I just filled up with premium, and it is running rougher than ever? Thoughts? :annoyed:

No error codes stored or present....

RonD · Dec 20, 2016

Welcome to TRS

Gasoline......................................
Two things happen when gasoline sits long enough, the good part, the "Go Juice", evaporates.
And the water in the gasoline, all gas has water in it, settles to the bottom of the container, in this case the gas tank, and the fuel pump suck gas from the bottom of the tank so...........lotsa water mixed in.
And when someone says "bad gas" what they are saying is it has too much water in it, causing rough running.

So the good parts evaporated in the fuel system and that leaves behind the additives, which has the scientific term of "Gunk" if I remember correctly.

You need to clean that "gunk" out of the fuel rail and injectors, but with engine running it makes that pretty easy.
Seafoam, or similar additive, will clean out the fuel system, so add directed amount to NEW gasoline in the tank.

The "old gas" should have been drained before trying to start, if that didn't happen then drain it now.
If you already added new gas then add some more and the "cleaner", fill it up all the way, try to dilute the old gas

After you run 2 tanks through engine see how it runs then.
Change fuel filter at that time as well.

Ford used a Waste Spark system, so pulling spark plug wires with engine running won't tell you much.

Coil pack should be fine, 2001/2 3.0l Ranger coil packs did have problems but wasn't pervasive.
So that would be a long shot for a 1999

And make sure you don't mix up coil pack spark plugs wires, they have a "odd" order on one side
1 5
2 6
3 4
Front

OR

3 4
2 6
1 5
front

the 5 6 4 side gets mixed up, 1 2 3 doesn't, lol

1 and 5 share the same coil in the pack, as do 2 and 6, and 3 and 4, so these MUST be matched

naford · Dec 20, 2016

The only thing I would add is. Change the fuel filter. I cannot remember where I saw it, but somebody wrote that the "gunk" plugs the fuel filter.

Mark Klein · Dec 21, 2016

thanks for the help
Well - I should have waited - but I had a motorcycle that did the exact same thing and a coil solved it.... Spent $85.00 on a new coil - No Change. So... Should I change the injectors or just add more fuel cleaner? I just tanked up on BP Premium. I will get some Sea Foam....

Mark Klein · Dec 21, 2016

Funny thing - the tach quit working when I changed the coil. What could have caused this? Only other problem is the air light bag comes on and off....

RonD · Dec 21, 2016

Airbag light will flash a code when key is turned on if there is a problem, it will be a two digit code, like 25, 2 flashes, pause, then 5 flashes

Often it is no more than a connector under a seat is loose or unplugged

If it is not a steady misfire, i.e. #3 is missing/dead, then injectors are working so no need to change them, let seafoam do it's thing and be patient for a tankful to run through.

Double check firing order on the coil pack, AND at spark plugs
tach runs off computer, not coil pack so that is odd

94tanner · Dec 21, 2016

If it ran great before being parked, 95% it is the fuel. Change the filter, new gas, seafoam. Problem is that you ran the old gas already and probably gummed up the filter/ran a bunch of water through your engine. 1 1/2 years with ethanol in a gas tank = water.

Sent from my SM-G925V using Tapatalk

wildbill23c · Dec 22, 2016

I'd recommend running through a tank of the highest octane non-ethanol fuel you can find along with a bottle or 2 of seafoam or something similar.

Letting a vehicle set with fuel in it for long periods of time is just asking for fuel system troubles, especially with the crap fuel today.

Mark Klein · Dec 23, 2016

Well - that is where I am at. BP Premium and sea foam - still don't know why the tach quit.... The rear spring mounts broke through when I jacked up the front end to change the sway bar links... Got them on order...

RonD · Dec 23, 2016

1999 Tach signal will be from computer, not coil pack, and not sure if it even uses spark as signal like before, I think Crank Position(CKP) sensor signal is used for tach now.

Ignition module was moved into the computer(PCM) in 1995 Ranger and been there ever since.
So either Tach is bad, or wire at dash or PCM is loose, pin 48 on PCM is the tach signal, tan/yellow stripe wire at PCM and dash

Check all 4 hangers, easy enough to pull the bed and do all 4 at the same time, have to grind off or torch out the rivets on the hangers.

aspevacek · Dec 23, 2016

Mark Klein said:
Well - that is where I am at. BP Premium and sea foam - still don't know why the tach quit.... The rear spring mounts broke through when I jacked up the front end to change the sway bar links... Got them on order...

Did you completely drain the tank before filling it with good gas? The bad gas will destroy the octane rating of the good gas you added if not.

Running Rough!

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