TBI to carb conversion on 88 model or similar??

This is all I have done trying to get this truck to run even a little better!!!! New double roller timing chain and gears, new distributor, new dual exhaust with glasspacks and without converters, (we don't have emmission testing here), all sensors has been replaced, rebuilt throttle body, new PCM, new vacuum hoses, plugs, wires, cap, rotor, coil, EGR valve, I have ran a compression test with 140-150 lbs per cylinder. I have ran 2 cans of mopar combustion chamber cleaner thru it and a can of BG 44K power enhancer. Double checked the throttle cable to make sure it is opening all the way. I have closely monitored the air pressure in the tires and replaced the clutch fan with a thermostatically controlled electric fan that rarely comes on. New fuel filter. It idles as smooth as butter and it is not showing any codes. I have checked it up and down for vacuum leaks or intake leaks and then I had my brother look it over also. I think it is anemic on power still and the 9-10 MPG is intolerable. I am about ready to burn it!! After torching it I may consider trying going back to a carb. I can rob all the parts I need off my 85 Dodge van, it has a rebuilt carb that is about a year old. What all is involved, do they make an adapter plate for TBI to carb or do you have to change the intake manifold? I guess you have to change the distributor also and I guess I would need the brains from the 85 also huh? Are their websites that give specific instructions on conversion? This will not be a daily driver anymore due to gas prices so a carb does not bother me. I need the power to pull my camper now and then. The way it is, if their is any wind it does well to pull itself. I really am ready to give up on the TBI and go to a carburetor. I am thru messing with it. It has to be within the computer system etc. It is the first year that PCM's were used on the trucks. Has anyone else done TBI to Carb conversion?

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1988 W-150 4X4 TBI 5.2 Liter Automatic 108,000 miles

You could probably find an adaptor plate, but 9-10mpg is bad for the 5.2, you should be up (3spd trans, no o/d?) in the low teens at least.

What size tires do you have on, and what gear ratios are you running?

Check the inside of the tailpipe; if it's wet and black then your mixture is too rich. You didn't mention air filter; have you replaced that, or done anything to let it breath on the intake end?

[QUOTE=fredjacksonsan]You could probably find an adaptor plate, but 9-10mpg is bad for the 5.2, you should be up (3spd trans, no o/d?) in the low teens at least.

What size tires do you have on, and what gear ratios are you running?

Check the inside of the tailpipe; if it's wet and black then your mixture is too rich. You didn't mention air filter; have you replaced that, or done anything to let it breath on the intake end?[/QUOT

The tires are a little large but not bad. I will have to check the rear end ratio. Does have a K&N air filter as well as new duals with glasspacks and no converters.

So do you have the 3 speed transmission, or is the early 4 speed o/d?

Did you have a chance to check the inside of the tailpipe?

So do you have the 3 speed transmission, or is the early 4 speed o/d?

Did you have a chance to check the inside of the tailpipe?


It is a 3 speed with no OD. I will check the tailpipe soon. I haven't driven it in 2 weeks due to its running not to my satisfaction and gas consumption problem. I did pull the plugs out a few times when I was driving it daily and they looked very healthy. I will post when I find out, thanks.

I don't notice any black or wet in the tailpipes. I am running a K&N air filter. I am having trouble determining which rear end I have in mine. On the 93 I used to have their was a sticker under the hood stating the gear ratios. None on this one. I can't find anything that helps on the rear end either. The VIN is 1B7HWO4Y9J5610583, is their any way to determine from it? Thanks.

Gear ratio? Usually a sticker of some sort on the rear axle; if it's not there, you can always try the "backyard mechanic" way to get your gear ratio:

Tape a piece of string to the driveshaft, have someone hold it, and move the vehicle slowly forward (or back) until the wheel has turned one complete revolution.

Count the number of times the string is wound around the driveshaft. Most Dodges had 3.21 or 3.55 gearsets for that year, and some may have come with 3.92.