We've got a puzzle - 1986 Bronco II --- UPDATE

[pasusan]

This is not about our RV tow vehicle, but it actually does tow a utility trailer once in a while....

We've got a 1986 Bronco II that is missing badly and we don't know what is wrong. If anyone has any ideas, we're all ears.

It has a 2.9 liter engine with electronic fuel injection and a rudimentary computer (not like today's vehicles).

It sat most of the winter (we don't drive it in the snow and salt).

Our first use of it this spring it ran really rough - engine shaking, exhaust coming out in stinky puffs. But then it cleared up and we took it to Lowes to pick up some lumber in our trailer. All the while it was running perfectly fine.

A couple of weeks later... We started it up and it ran really rough again. This time it did not clear up and actually conked on the side of the road and then wouldn't start. I know - I shouldn't have taken it out of the driveway, but I was 90% sure it would clear up like last time. Checking the oil dipstick - we smelled gas.

We had it towed to our local garage and asked them to diagnose it. They told us the fuel pressure was good and they think that it was condensation in the distributor cap and to do a complete tune up - as the plugs were totally fouled. Oh - and then the mechanic mentioned that it might just be the ACT (Air Charge Temperature) sensor that was giving a wrong reading causing a big fuel feed (like an automatic choke).

Anyway - we did the tune up and it still ran rough. We replaced the ACT sensor and it still runs rough. At least it starts right up with the new clean plugs! But we don't want to run it long and foul up the new plugs.

So... What could be wrong - it cleared itself up once and now it won't. Any ideas?

[pasusan]

We had it in to our local garage and they found the EGR valve was totally clogged with carbon. After changing that out and cleaning things up it ran well except at idle. We asked if the ECM had given any codes and they said they weren't able to communicate with the ECM. :h

Anyway - we put in a new ECM and all is well now. So I guess it was 2 problems - EGR valve and ECM.


Thanks much to all who tried to help.

[4X4Dodger]

68ltd wrote:
Those ford 2.9 v6 engines are known for cracking heads.

A blown head gasket is always another possibility when it runs like this. Take the radiator cap off and try to start it. If you get a geyser of water out of the radiator it is very likely you have a blown head gasket.

[68ltd]

Those ford 2.9 v6 engines are known for cracking heads.

[B_O__Plenty]

Ummm...back it up to your computer and let me hear it.... While you might get the right answer here it is pretty difficult to diagnose and it will most likely be a guess. Before you throw too much time and parts at it based on a "best guess" why not take it to a good shop and get a proper diagnosis?

B.O.

[Huntindog]

Have you checked the air in the tires lately?

Seriously.... Asking for a diagnosis on the internet can only get wild guesses for responses. I won't even make a serious attempt at it. Good luck.:B

[carringb]

pasusan wrote:

Big question - what to do with the 15 or so gallons of this gas like liquid???

Does you community have a Hazardous Waste collection site? Some areas do periodic collection events. I wouldn't even put it in your lawnmower, because it could foul the carb. Please don't use it as weed killer. It will get into somebody's ground water eventually.

[pasusan]

4X4Dodger wrote:
Sounds to me like your timing chain may have jumped a cog. There very well could be more than one thing going on here.

Thanks... I sort of doubt that (hopefulness here) as it is a newish Jasper Engine.

As for draining the gas - we did that and then found non-ethanol gas in town to put in it and it still runs cruddy. Even with the Lucas gas treatment.

So - we think we're going to take it back to the garage and just tell them to fix it.

It will be interesting to find out what it is as we have 2 classic vehicles stored in the barn that start up perfectly a few times a year - with some pretty old gas with stabil. Not to mention a tractor that sits most of the year only being used for snow removal. And Geeze - not to mention our tow vehicle that sits for 7 months a year. (Although the last 2 have carburetors that we clean with Gumout once in a while.)

The good thing about this is we found a somewhat local station that sells the non-ethanol gas at 91 octane. Definitely going to use that in our power equipment.

[pasusan]

The Texan wrote:
There are hazard waste collection points all around the nation. Call you local waste management and ask them where to take it. Usually it is free, as they do not want you polluting the country side.

Thanks - of course DH was kidding about the garden because it seemed more like water than gas... We're calling our township tomorrow...

[4X4Dodger]

Sounds to me like your timing chain may have jumped a cog. There very well could be more than one thing going on here.

[The_Texan]

There are hazard waste collection points all around the nation. Call you local waste management and ask them where to take it. Usually it is free, as they do not want you polluting the country side.

[pasusan]

Thanks very much for the responses.

We are now draining the gas ... and it hardly smells like gas!!!

The tank was full all winter - actually since 8/28/14. 😮

Big question - what to do with the 15 or so gallons of this gas like liquid???

DH said sprinkle it on the garden. :E

[carringb]

I would be suspect of water in the fuel. Keep in mind ethanol (incl e10) absorbs water from atmosphere. It does not sit well for extended periods without treating it, and also keeping the tank all the way full to minimize the air in the tank.

[marcsbigfoot20b]

I assume you changed the oil that was diluted with gasoline.

It is possible you have an injector leakdown caused by buildup or varnish that drains them into the cylinder when sitting then leaks past the rings into the crankcase.

If you do have bad spark and the plug does not fire you can flood one or more cylinders and the gas leaks past the rings into the oil also.

What happened to me 2 weeks ago on my 99 Tahoe.....passenger O2 sensor plain quit dead, not lazy but dead. First time I have seen that happen from OK to dead in one drive. It ran full rich as the computer would go (25%). Just driving 30 miles home from work partially melted my headers ceramic coating off. It ran like******at idle.

[nevadanick]

I had a Ranger in that time frame that a part in the distributor failed. Cant remember exactly what it was called but i think it was what triggered the spark.