I got my 91 b2200 Auto transmission truck over the weekend. I was expecting at least 20 mpg. I averaged it out and it came to 17.9 which is not acceptable. That getting close to what my v8 352 powered truck gets. I was driving in the rain at a slower speed during this time. Plus I turned off the overdrive through town. But I drive about half the miles on the interstate. I didn't get above 70 mph on the interstate. Is there anything on these that goes bad to cause bad mileage or any tricks I can do to get better mileage. Its really sluggish compared to what I am use to, and as small as the engine is I think I should get in the 20s . Help me before I push it over a cliff.

 

I take it, its carbureted. If it still has the stock one on there its probably the O2 sensor or possibly the fuel mixture is running alittle rich. also theres no reason to run without overdrive in town as its set to shift in and out of overdrive when the power is needed giving better gas mileage...

 

It has had the engine replaced but it was suppose to be the same engine. The idle does seem to run higher than it should. I will look into the co2 sensor also. I have been looking at the weber carb conversion and think that may be a option also.

 

If you do the weber conversion make sure you dont have emmissions in your state or county. Also dont waste money on an O2 sensor if your going to do the weber conversion.as this will eliminate the O2 sensor and most other wires and hoses under your hood.

 

The person who changed the engine out I assumed did away with the hoses. There are places where the hoses went that do not have them. The ends that go into the exhaust were nipped shut. I am wondering if it even has the co2 sensor. I am thinking since studying the preveious post that it is the fuel running rich. I was told it sat for 3 years with old gas in it. I am thinking they may have turned up the idle to make it run. The idle seems to me to run way too fast. You have to hold the brake pedal down hard at redlights to keep from running them. Plus the exhaust seems ot be burning too much gas,it is really strong in burned gas exhaust. Plus it has backfired 2 or 3 times when turned of and a few times it keeps running "dieseling" I think its called. It finally will quit. I am going to experiment this weekend. I think he may have only turned up the idle screw. I hope he didn't mess with the timing.

 

Its supposed to idle high about 1000rpm, but i think its running to rich and dumping to much fuel into the bowl. But you may want to connect all of yoru hoses as they are kind of needed for this carb to make the truck run as normal as it can. This may actually be causing all of yoru problems. The O2 sensor you can follow the wire back and see if it is connected to anythign. That would cause more problems if its not as well. Also make sure your choke is not on all the time. As this will make you run RICH all the time. I would check all of these first then go from there... Have you actually done a tune up on it yet? I reread all of the posts here and you didnt mention it. Kinda had me thinking. After the hoses are all put back the tune up may help you Tremendously. With the tune up dont forget the fuel filter. Small thing alot of people overlook.

 

I agree with you on the running rich part. I think thats exactly whats going on. I take it I just adjust the idle screw for that? What else do I need to adjust? I was tinkering onit tonight with the idle screw. I turned it down and could not tell a difference in park.I got my wife toput it in gear with the brake on and adjusted it down. One thing I did notice is that the choke is unplugged. I don't know what it plugs into.The choke is open but not all the way. The idiot who changed the engine out left things unplugged and unhooked like crazy.So I got to find out where everything goes. As far as tune up what should that pertain? I am thinking points and plugs. I am by no means an expert on engines but I am willing to learn. I have set my 66 ford trucks timing and distributor by hand with no timing lights and it runs really well. But this small b2200 engine now gets the same or less mileage as my ford and its half the size engine. So I know it has to be able to get better.

 

Ok full tune up is basically a Fuel Filter, PCV Valve, Distributor Cap, Distributor Rotor, Plugs, Wires, O2 Sensor (Dont replace this if your going to use the Weber) Oil, Oil Filter, Air Filter, that should be it.

The Choke plugs into the back of your alternator. Theres alittle spade connector on the back of the alternator and the choke wire plugs into that.

I really wouldnt have messed with teh idle screw until you had all of the hoses put back on in their correct places. Do you have a tachometer on your truck? Cause it may sound like its idling real high but it could be that your motor is just running loud. And like i said the truck idles high anyways, like inbetween 800 and 1000 rpm... and with it being older lean more towards the higher end of that.

A vaccuum leak will also cause it to idle high. After you get all of the hoses back where they go, take an unlit propane torch and go over all of the vaccuum connections including the really small ones and at the base of the carb. If you notice it idle higher then you've got a leak there.

You said you adjust the timing on yoru old truck, its going to be the same here as well. Nothing different has to be done, these trucks have timing marks on the crank i believe like all the rest of the trucks out there...

Keep us posted on yoru progress and any other questions you have ill get back to you as soon as i can with an answer. And it doesnt take a mechanic to know or do this stuff either, i mean all i really know are things ive learned on these forums. But safe to say, you havent asked a question i couldnt answer "yet".

Good luck and please let us know how it goes.

 

***** i have a diagram of the vacum hoses for 1991 b2200 truck e-mail me and I'll send you a copy.
my e-mail is leopardon1@yahoo.com.

 

I got the new webber carb and had a mechanic I know put it on. I thought about doing it myself but I got him to do a tuneup and check it out good. They sent the wrong jets he said but it runs now. I think its getting better mileage. He said with the correct jets in it should run even better. I will take pictures in the next few days and put the link up. But its starting to look up on the truck.