hi, i have looked all over in my manual and i can't find what size carburater i have. it's a stock 1985 B2 4WD. i was wondering if any of you guys would know. i am planning on rebuilding it or putting a new one in for better emmisions.

thanks

 

You've got guts, BroncoDude! As far as I know, there weren't any other carburetors than the one two-barrell for that engine, nor were there any aftermarket replacements. It's made to work with the engine's computer (ECC), that monitors various aspects of the engine's operation (throttle position, exhaust gases, and any of a variety of smog control devices used) to maintain the best possible performance and fuel economy.

If your engine's running poorly, check ALL your vacuum lines and sensor wiring and connectors. Also, if you have the coffee-can style vacuum storage cannister on the right fender (plastic) shroud, remove it to inspect CAREFULLY for cracks. Look for small rusty trails on its surface. Rust probably means cracks and cracks means lost manifold vacuum which can wreak havok on an engine's control computer program.

If you can retrieve the ECC's error codes, find out what it's seeing wrong and either repair or replace the faulty device(s). Certain of those devices will cause the computer to revert to a "Default Mode" of operation, which is just stable enough to get you to your destination, preferrably a local repair shop, to get the problem corrected.

One of those devices is a TPS (Throttle Position Sensor). My '84 developed a dead spot that made it think the throttle was beyond closed, an invalid reading, and the computer went "stupid", rather than try to work with it. Thirty-some-odd dollars and a new TPS got it working again.

If you don't have references to help you retrieve the error codes, get yourself the Haynes service manual. It's pretty good for that part of problem diagnosis. Once your ECC is giving you nothing but the "Pass" (11) code, and nothing else seems too abnormal (i.e. smoke, very poor performance and/or fuel mileage [less than 19-20 MPG]), I'd say it's running as good as it can be.

Normal HP of that engine is just 115 at around 4500 RPM. When Ford went to the EFI 2.9L, they got 25 more HP out of it. That's about 22%; a significant gain for just a 100cc's increase in volume. That much HP/cc wasn't achieved again with subsequent capacity increases on the Bronco-IIs, which says a great deal for the changeover to Electronic Fuel Injection.

Still, the 2.8L was no 'pup', especially when it was mated to the 5-speed manual and the driver knew how to use it! Good used parts can usually be easily found for them at many salvage yards nowadays, and when they can't, new and rebuilt parts can be gotten at many auto/truck parts chain stores.

 

it's not that it's running bad, it actually running good, it's just having a hard time starting up in the morning now, and it's bellowing smoke, and getting crappy milage, 15-17. but one it warms up the smoke tends to lessen.

thanks for the help

 

if it were mine ide leave it be.typical ford pump it three times turn the key let it warm up for a min. and then go on your way. 300,000 miles + and still going strong

 

You should be getting closer to 22 MPG, so get what you need (Haynes #36070 Service Manual is a good reference) to retrieve those ECU codes and correct all the faults you can. That engine had several smog devices. For example, the EGR valve has a feedback circuit, too! The EGO (O2 sensor) is vital to good performance and economy, though it doesn't begin to function until the engine's been running for at least several minutes.

Make sure your air cleaner preheater vacuum controlled valve is working, too. Efficient fuel vaporization and thus its complete consumption is aided by warming the incoming air, though not too much. My air cleaner's vacuum motor's diaphram was rotted through as well. They're hard to find at parts suppliers, so I had to go hunting for a good one at the local salvage yards. Out of several I spotted, only one still had a good rubber diaphram in it. It was on a Ranger I-4's air cleaner. I yanked the snout off the cleaner and after returning home, got it to work on my V-6 air cleaner. Don't forget to check the condition of the flexible 2" perheater tube going to the shroud on the left exhaust manifold. It's needed to complete the setup.

And it wasn't until I was doing my 2.9L EFI V-6 "upgrade" that I noticed the cracks in the walls of that coffee-can-like vacuum storage unit, on the right fender shroud, that was probably robbing my engine of a few HP. When you only have 115 of them, you can feel the losses that result from all the little things! If you find cracks and are looking for a replacement, find and somehow mount one of the semi-dome-shaped plastic ones some Ford cars and trucks use. They hold up better!

As I mentioned previously, the Throttle Position Sensor (on the passenger side of the carburetor) on my '84 went bad with just 180K miles on the ticker, and the ECU partially shut down as a result. The engine would tend to stumble when pulling away from a stop, and fuel mileage was very poor.

Replacing it improved both performance aspects, though not by as much as I was hoping. But, by then the engine was really showing its age anyway. That's why I got the '88 parts vehicle and did the upgrade. Man, what a JOB that was! (but WORTH it!)

 

Hey Broncodude3, just saw your post. You most likely have a Motorcraft 2150 carb. I have an 85 also, I found this cd on ebay a while back which has helped bunches. Try to contact me by email Hope this has helped
reddeer52