2.9L burning rich?
 

My '87 ranger with a 2.9L with 170,000 has a problem I'm trying to troubleshoot. When driving down the road it will suddenly start missing and puking black smoke out the exhaust like it's burning too rich. then suddenly take off like nothing is wrong. I just changed plugs, wires, cap and rotor thinking maybe an electrical problem but it does the same thing.

maybe something with the cold start choke? unsure of where to troubleshoot next. all wiring looks ok.

any help would be appreciated. thanks in advance.

"Cold start choke?" What the heck is that? It's been so long so I've done any work on a carburator, I can't remember specifics.

Unless somebody's done some major modifications, your 2.9 is fuel injected, so there are no chokes. 1st things I would do would be to 1) pull codes from the EEC-IV computer to see if the computer has seen a problem and 2) check the vacuum line to the FPR for gasoline and test fuel pressure. Both operations are described in Ken00's tech info post at the top of the BII or Ranger forums.

it is fuel injected so no carb. would there have to be a check engine light on to get a code? the engine light has never stayed on like my 96 F150 that I can read a code with. I'll check some lines. thanks

Most if not all '87 didn't even have a functional check engine light installed, so the answer is, "no the CEL doesn't have to be on for there to be a code."

Also, even if there were not all problems generate a code, and not all codes trigger the CEL. The fuel delivery system is only partially controlled by the computer and the FP regulator is not under computer control so a proplem there would not in itself generate a code. If the problem in turn affected other systems then a code might be generated, such as A/F ratio and its' affect on the O2 sensors...

You could still pull the codes and check them, there may indeed be codes stored in the computer.

I would try switching out the distributor, my friend had a similar rich condition and it was partly due to a shot distributor.

1987 2.9L V6 Ford Ranger Burning Rich...random in unpredictable black smoke
 

Well I have been to just about every mechanic in the area including ford dealerships...no on can find the problem. I know the exact problem you are referring to. I have an 1987 Ranger with the 2.9L. It will run great for hundreds of miles and then start bucking, missing and blowing black smoke out the pipe like crazy. I've replaced just about everything possibly...FP regulator, O2 sensor, air temp sensor, air filter, plugs, rotor, dist cap, plug wires, FUEL INJECTORS. I have had the codes read numerous times, even was told that snap-on throttle body cleaning system was the answer (I can't belive I fell for that one) Anyway, I have another friend that had the same problem...it seems to start when the Ranger hits around 150K. I consider myself pretty knowledgable regarding fixing cars but this has me stumped...I am convinced it's an electrical problem in the ECM but I don't know how to fix it...Oh by the way I replaced the ECM too.... Did you get an answer on this one yet???? I would love to know the answer to this one.

I am also having the same problem, minus the black smoke. I have been looking for an answer to this for months, so if anyone has an idea I havent thought of, I'm all ears! Everything fuel and spark related has been replaced except the ECM and injectors. Not sure if it's worth dumping more money into it to have those parts not fix it either. The only code I am getting is 25 for the knock sensor ,but I performed the flow chart test with the koer "hammer test" and it checked as good. I am stumped!! ps. Fuel pressure is steady at around 38-40.

Well I bit the bullet and replaced the injectors.... As for the ECM I got a used on from a local auto yard and replaced that with a used one.... Fuel Pressure in fine....What is left to check....? It's been months for me as well. I finally parked it in a barn in hopes that eventually I will come across the answer. I really don't want to junk it

Yeah, my truck is parked too. I think the next step I am going to try is taking off the upper intake and completely clean the injectors and fuel manifold and test the injector harness. From what I have been reading, the computers RARELY go bad in these trucks, but you never know. The problem I have is constant, so I will know right away if this works or not.

Like I said I put new injectors in and that didnt' help....I guess it could be the wiring harness; but I find that unlikely since I don't think only one cylinder is the culprit and what are the chances that the wiring harness broke in two different spots??? Well if you get around to it keep me posted! Thanks.

'89 BII same problem. Rebuilt engine and heads. cleaned upper and lower intake, IAC valve, intake air temp sensor, and throttle body. when I put it all together, it was running pig rich and blowing black smoke, and missing like crazy. I have double checked timeing to be at 10* with spout connector dis-connected. I do have a CEL staying lit and I'm fixin to pull codes this week. Checked pressure regulator and didn't smell gas in the vacuum line. Will be checking fuel pressure also but that doesn't seem to be a problem. Sounds like we could use a "miracle" fix. HA HA HA. Any Ideas out there?

When the FP regulator goes bad, it doesn't always leak fuel into the vacuum line. I would for sure check the fuel pressure. And make sure that you have good vacuum at that line on the FP reg. If the line is cracked or broken the FP reg. won't work properly.

Alrighty guys I swear I have the answer. My buddies 86 out of no were did the exact same thing as yours. Its started running really rich and bogging. we started to replace everything and were getting no codes regarding the problem, we had no luck in solving the problem. so we took it to a place called Jobrite up here in Canada that works on mostly fords. It took them a few hours but after looking over the whole wiring system they came across one blown fusible link and the the internals of the distributor were shot. so they sold him and used distributor and fixed the fusible link and WALA it runs amazing now. Just go over all your wiring and specifically check you fusible links and for sure the distributor pickup, which is inside the distributor.

1. Replace ALL vacuum lines.
2. Check to see if the MAP sensor holds 5lbs of vacuum using a hand pump.
3. Replace the 2nd fuel filter on the driver's side frame rail...change it.
4. There is a vacuum actuated valve that the filter goes bad. It is on the
passenger firewall and has two hard vacuum lines to it, one red, one green.
change it with a new one.....sorry, but I can't remember what it is called.
5. last thing I would do is to install a new Distributor and TFI as a unit.
These five things stopped my Rich running 2.9.
Good luck.