RAM 50 4WD with 2.0L gets very poor mpg.

[iwantabuggy]

This is my first post here.

I have an 89 D50 4WD with the 2.0L. It ran really bad when I first got it. Gave the engine a tune up, complete with O2 sensor, cap, rotor, plugs, wires, fuel filter, and adjusted timing to 10 BTDC. I have not changed the oil yet, but I'll be doing that in the next few days. My mpg was 12 when I first got the truck. Now I am up to 16 mpg. The truck seems to be running pretty good now, but I am thinking I should be getting at least in the low 20's mpg. Oh, and it has 113,000 miles on it.

Any suggestions? I'd really like to keep the truck. I like it alot, but I won't be keeping it if 16 mpg is the best I can get out of it.

[4doorciv]

You check all the fluids? Tire pressure can also affect miles per gallon. I'd check for vac leaks like cracked vsf lines and stuff.

[iwantabuggy]

Thanks for the reply. I checked all the fluids and tire pressure first thing, just forgot to mention it. Have continuously been looking for vacuum leaks and have fixed a couple, but they didn't seem to help. Last night (when checking again for vacuum leaks) I found a small device in one of the vacuum lines. It looks like a filter or something. It is white on one end, black in the middle, and yellow on the other end. I took it out and since it looked like a filter, I tried to blow air through it and could barely pass any. I tried to buy a new one, but the parts house couldn't find it in their books. After working with them, I believe it is a vacuum delay valve. I have no idea what that is for or how it would work. Doesn anyone know anything about such an item? I also don't know if it is directional. I forgot to note which direction it was in originally, so it could be in backwards now. If you know anything about this device, please enlighten me.

Thanks.

[camoit]

Yes it is a delay, and yes they are directional. The side you can draw air from goes towards the vaccum source like the carb. I'm not sure on your truck but a valve adjustment wouldn't hurt. It might be a hydrolic adjuster so there would be no adjustment then. Also with that many miles on it you should change the timming belt if it has one. That would make a huge diferance if it is old and streaching. If it's fuel injected clean or change the injectors. There is some good cleaners that you hook up to the fuel system and it will clean them out. Bad or broken injectors will reduce mpg. Incorect fuel rail pressure has an afect on it as well. Let us know what you find and how you fix it. There are lost of un-finished threads that leave you looking for answers.
PS: This thread would get more responces under the "tuening" section for bad fuel milage. I can move it there if you want.

[4doorciv]

From the year I'm guessing carbed. I'd dump a bottle of seafoam in the gas tank with your next fill up but there are others out there. Also clogged vac lines as well as internal carb problems. But knock out the easiest first.

[iwantabuggy]

Yes. Please move this thread to a more appropriate group. Thanks.

This is a carb'd motor and until you mentioned the belt, I was pretty sure that it had a chain. Now I've looked in my book and it shows a belt. I should dig into it and get it changed. Especially with the age of this one. I dumped some GUMOUT Regane in the gas tank yesterday. It's probably too soon to tell if it helped. Seems to not be running quite as well as it was since I put it in there. Maybe its because the delay valve is on backwards? It doesn't flow air through it very well either direction, so it is hard to be sure which way it is supposed to go. Also, both ends connect to the carb, so again, don't know which direction to put it. I'm trying to find a new one. According to my book it is supposed to be open when vacuum is supplied to one side and closed when it is applied to the other side, but the book doesn't say which is which.

[iwantabuggy]

Just looking through my book further and my motor style appears to be a 1979-1982 motor. Which has a chain. Apparently the motor was changed out at some point. That my change things some. ???????

[crvtec90]

If your motor has a plastic timing cover then it has a belt. If the cover is all metal then it is a chain. Timing chains are lubed with engine oil so the engine needs a metal cover.

[iwantabuggy]

It has a metal cover. I've been trying to find the landing tab, but I just don't see it. Probably to much oil and dirt on it? I'll keep looking. I've been looking on the left side near the exhaust manifold. Also looked on front near the distributor and down near the timing mark, I'm just not seeing it. The metal tab at the back of the engine compartment says it should be a G54b, but I suspect it is not the original engine.

[iwantabuggy]

I found the landing pad, and no, I didn't click the link. I didn't see it. My engine is the g54d. I definitely had to do some rubbing to see the numbers. It was pretty rusty right there.