Please help...

Alright guys this is my first post. There seems to be ton of threads related to carb issues and what not, but I wanted to share my issues and get opinions.

Bought the truck to get to work and back. 1988 B2200 with 238,000 miles, stock carb. Since I bought the truck I replaced the gas tank due to leakage when filled over the half way mark, fuel pump, also I had the ignition switch replaced after it completely died on me one night. The truck drives great, but I am having some issues. *note, it fired up this morning and it was around 15 below zero (minnesota).

On a typical cold morning, the truck will start one of two ways. First, it will start up (CEL) and the choke will kick in, rev hard until the gas is pressed again and the RPM's come down (sometimes keeps a high rev after pressing the gas until truck is warm). Second, the truck starts up (CEL), but the choke never seems to work, idles like a tractor, and blows black smoke and soot from tailpipe. At that time the engine seems loaded up and have to clear it out with a few good revs. So then I take off, runs good above idle with the occasional miss during acceleration. Runs good at cruising speed, slight crackle and pop when letting off the gas. Also, when cruising the CEL light comes on and off. Seems to go off when letting off the gas, than back on when on the gas. Now for the good stuff, I was averaging about 14 MPG, until last week. Last week was very cold, so I had it running 20 minutes prior to work everyday. I got 9.5 MPG and 130 miles to the tank, all highway! So I read these posts and I get frusterated because it could be so many thing. Where do I start?

Now the secondary "minor issues", passenger side blinker blinks fast in the rear, and not blinking in the front. I replaced the bulbs in the running light and turn signal, and checked the rear bulb. Alll seem to be fine, but I can't figure out why I'm not blinking properly.

Lastly, when filling the gas tank it overflows once I'm about 3/4 full, I have to fill very slowly to achieve full. I was very careful during my tank swap, but maybe I pinched the vent? where does the vent go? Or did I get the vent and rollover line mixed up?

So like I said, the truck seems to always start and run (with issues), but it's doing it's jpb getting me to and from work, but I need to improve my mileage! I bought the truck cheap and don't plan on dumping money into it while chasing problems. My thoughts include, coolant temp sensor, verify vacuum leaks, new intake gasket, verify EGR valve and replace gasket, carb rebuild kit?

Thanks

Little update, I replaced my coolant temp sensor today. It seems to be running better with no noticeable missing, but upon initial start up the Blake smoke was there. Can't tell yet if my mileage has improved as I need to put more miles on. Also I got all my lights and blinkers working. I had to clean up the sockets with some sand paper.

Looking more at the carb today, are the mounting gaskets supposed to be roughly 1/8 inch thick? The same goes for the air horn gasket. Also I'm still confused how the reed valve intake thing works. My air filter was new within 2000 miles but now it appears fouled and heavy. With the black smoke I'm sure it's dumping back up into the air filter and fouling it up. I feel like I am going in circles. Do I purchase a rebuild kit and attempt to go after the oem carb? Or do I ditch the carb and emmisions, and go weber? Or am I completely off track?

Do you have emissions testing in your state? If not I would go with the Weber and emissions delete. If you do have emissions testing then you might be better off with the stock carb. The issues you are describing point to the carb being in "limp mode". Has it had a tune up recently? Also a good idea to replace the fuel filter if you haven't already done so. I don't have much experience with the stock carb on these trucks but there are a lot of members on here that do. It also sounds like you need to check and make sure the choke is working. On cold start it should be closed, after the engine is at operating temp it should be all the way open.

The stock carburetor on these is extremely complicated, to say the least; would not try a self-rebuild. Some have purchased rebuilt carbs and been happy with those, like from National Carburetors Jacksonville, FL 32216 904-636-9400. Personally, I've had a Weber on mine for 9 years, runs nice. But all your engine issues may not be carb-related (oil in air filter, smoke).

Thanks for the replies guys, Minnesota does not have any type of emmisions testing. The truck has not had any formal type of tune up as far as I know, but the plugs and wires appear new.

The PTC heater, how does that work? What appears to me is a thick rubber type mounting gasket? I would think the gasket should be paper or cork based and not 1/8 inch thick. I did notice a foam filter coming into the intake from the reed assembly, but it too appeared very fouled and wet.

So the stock carbs are very engineered, but why do you say they are complicated? What would so difficult in pulling the carb apart and going thru it ensuring jets, needles and floats are doing their job?

Lastly, last night while I was meesing with the lights, I could smell gas in the engine bay and could hear some type of bubbling. Maybe it was my coolant cooling down, but it seemed like fuel was still moving somewhere.

The stock carbs are a pia to work on for me, I'm used to the old quadrajets and carters. The stock carbs have 2 or 3 sensors in them and they are finicky. Being you smelled fuel sounds like its running rich still which can stop up the catalytic convertor over time. If you have the patience to rebuild that carb then its worth a shot if you want to keep it stock. I'm with Cusser on this, that many miles on that engine it sounds like you have some blow by.

Remember this black smoke is only during start up and usually when it's very cold. Once warmed there is no smoke. Let's say there is blow by, does that mean my mileage will drop to 10-12 MPG's? Why would blow by cause a huge increase in fuel consumption?

I shouldn't even say when it's warmed up. Even when cold, a couple revs to the engine will clear the black smoke.

The blow by wouldn't cause that much of a mpg loss. Vacuum leaks, bad carb, fouled plugs and a stopped up catalytic converter can cause that. Being you are getting that low of mileage can mean a few things. I'm still leaning toward carb issues myself. 10-12 mpg is a pretty nasty loss of mpg in these trucks.