90 Ram Van B250 Bad MPG and black smoke (running rich)

[ninevolt]

I recently purchased a 1990 Ram van it says 250 on the side. It has the 318 engine I believe.

If you have it idling there and give it some gas it usually blows black smoke out the exhaust and smells horrible to drive with windows up or down cause smoke always gets inside.

I have heard a weird rattle from the catalytic converter area but it hasn't been rattling lately. One mechanic told me that it was the catalytic converter which was bad and if I got that it would feed back good data again to the engine about the oxygen intake and fix the black smoke/fuel consumption problem.

Another mechanic told me it was the oxygen sensor and I later found out he had not even looked at it while it was there for 36 hours. Then he told me it was the coolant temperature sensor or something like that.

My dad told me it could need a "valve job"? When I got the oil changed they said that it needs to have a procedure done to clean out the engine next time I take it there cause it was "gunked up" or something.

I am having a hard time figuring out what it could be, I have read alot of forums and they all say different things. Does a 90 250 have a choke which can get stuck?

I have tried running seafoam? injector cleaner in it also but it didn't seem to do anything.

Any information would be appreciated.

[landyacht318]

It sounds like the previous owner did less than the minimum maintenance required. The rattle from the catalytic converter could just be the heat shield rattling. Knock on it with something. It could also be a damaged unit. Many things can cause the engine to run rich. The O2 sensor could be toast, the coolant temperature sensor could be telling the computer that the engine is still cold so it adds more fuel. If your air filter is extremely dirty it will be starved for Air and run rich. Running a can of Sea Foam (IMO an excellent product) through an engine can destroy or foul the 02 sensor. It happened to me. It certainly smells horrible when run through the throttle body with the engine running. A full can in a gas tank with only a few gallons in it will also cause your exhaust to smell worse than usual

If the engine is sludged up, the previous owner did not change the oil enough. If you try to run some sort of sludge miracle fix engine flush in a bottle, it most likely will clog the oil pick up screen. Your oil pressure will drop to next to nothing and very soon the engine will be toast. Do not let any quik lube places sell you anything more than oil and a filter. I won't even trust them for this. Short of an overhaul, your best bet for sludge removal is frequent oil changes. If you just had an oil change, check the color of it on the dipstick. It should still be a fairly transparent brown. If it's dark brown or black, then learn how to change it yourself and do it every 250 miles.

There is no choke on your engine. The computer controls the air/fuel mixture. It takes reading from the coolant temp sensor and o2 sensor among other sensors and determines the correct fuel air mixture. In fact the best place for you to start with any engine issue is to check the computer for error codes. This can be done by turning the ignition key from full off to on(do not engage starter) to off 3 times. On the third time leave the key on and watch the Check engine light. When it goes off get ready to count.

The C/E light will flash on and off at a regular interval and then pause and then start flashing again. For example, flash-pause-flash-flash is a code 12 which indicates the battery has been disconnected within the last 50 key starts. One your model year there are only 2 digit codes. A long pause means a new code is ging to start flashing.
5 flashes pause flash is a code 51 which means the o2 sensor is reading a rich or lean condition (I can't remember which). A code 55 means end of codes. You will definetly get at least a code 55. Resetting the computer can be accomplished by disconnecting the battery for more than 30 seconds. Sometimes doing this can temporarily cure a driveability issue.
Had I known this 5 years ago I could have saved mucho Dinero paid to unscrupulous dealers and mechanics.

Do a google search for the codes, many different sites have a full listing of the codes and a better description on how to read them. It is sometimes referred to as the 'KeyDance' and it is the first thing that should be done when something is amiss.

Usually is is blue smoke, not black which is indicative of a required valve job. 318's to my knowledge are not prone to sludge. When mine was rebuilt there was none, anywhere.

A very good dodge technical forum exists at allpar.com but everyone there will ask you the computer codes before guessing. So figure them out and post them here or over there and maybee someone can pinpoint your problem.
Also, Smoke getting inside can kill you. Make sure the windows and doors are closed/ sealed in the back, and if it is still getting inside then you've got a hole in your floor and a leak in the exhaust, and if your exhaust is that bad, it is a good possibility that the cat converter is shot and causing some of your driveability issues.

Unfortunately, unless you paid a very small amount for this vehicle, I don't think it will be worth throwing money into it. If something so simple as oil changes where too much of a burden for the previous owner, then it's likely everything else has been ignored. If your transmission fluid is not pink an it smells burnt, or anything but sweet, well.....
Good luck. Check your codes and post them

[ninevolt]

I just checked the fault codes; it just read me a 5 5 which means no codes. Wouldn't there be codes telling me whether it is the oxygen or coolant temperature sensor if those are broken since the computer is connected to them? I checked the oil when it wasn't warmed up and the oil was black but didn't smell burned, I got it changed about a month ago and it has had time to mix with the sludge I guess. I couldn't find the transmission fluid dipstick. What are people referring to as the doghouse? I noticed that it looks like I can take off the area inside the van in front of the radio (large plastic hump thing). It looks connected with clamps that can be unclamped. Will I be able to access anything interesting if I remove this? Also, I made sure not to put too high a ratio of sea foam when I was putting it in my gas so I don't think I messed anything up with that. I don't even know where my air filter is located, they didnt have one when I got the oil changed. Another thing that's weird is when I turn my A/C on high, smoke drifts up out of my gauges for oil and the other one but when I have it on vent it doesn't do this so I leave it on vent. My switch on the A/C to change high/low/medium was really hot to the touch when I tried changing it also.

[B-300]

The air filter is in a housing like a carburated engine, under the doghouse. (The cover over the engine on the interior of the van)
The computer will only throw codes for the 02 sensor or coolant sensor if they are outside of the range they might run at from cold start to warmup or if they don't change readings such as a shorted wire would do.

[landyacht318]

It's good that you had no codes come up, however that obviously doesn't mean everything's groovy. Once I noticed my mpg dropped and was not getting any codes. I checked the resistance on my Coolant temp sensor and found it about 40% off. I replaced it and started getting better hwy mpg than I'd ever seen. It would get a code if I removed the wires leading to the sensor, but the faulty readings of the sensor didn't set a code. Same thing happened with my o2 sensor. At least you've determined that the connectors/ connections are still okay.
A lot of mechanics hate Vans simply because of the fact that removing the doghouse can be a pain in the ass compared to pulling a latch and opening the hood. Myself, I love being able to sit in a comfy seat when I work on it. Driving with the cover off gives you incredible insight to how your engine is running.
Your quik lube place said they didn't have one a filter simply because it would take them too much time, and filters are cheap. simply put, they would not make enough money by selling and installing one for you.
To check the filter, remove the doghouse. The 2 clamps you see, and there are 3 screws in the floor. Pull up the rug or whatever at the base of the doghouse and loosen the screws with a large flathead screwdriver. Twist the hold down clamps to the side and re position the rug flat again. Put the passenger seat all the way back, and lift out the doghouse.The Air filter housing will be that big round thing on the top of the engine. Sweep off any dust and dirt and unscrew the wingnut. Lift off the cover and presto. Do not let anything crusty dirt, dried bugs drop into the center of the filter. (throttle body). It'll be obvious if the filter is dirty. Most likely it is. Wipe the interior with a with paper towell and replace the filter.

In your first post you'd said the mechanic never even looked at it.You never mentioned the mileage on the vehicle or the mpg you are getting. Take a quick look at the spark plug wires and see ithe rubber coating is cracked on any of them. If they are then most likely should do a full tune up. New plugs, wires, distributor cap and rotor. It should be noted that spark plug wires can look fine and still be bad. Does it run crusty when it's cold after a good rain? A sure sign. Run the engine with the air cleaner cover off and try to see if is running smoothly. Shine a light down into the throttle body and see if the fuel is spraying from both injectors evenly. You'll hear them clicking away. Are they both clicking at that same tempo? You can put a finger on them and feel. Rev it a few times and see if they behave similarly. Shut the engine off and see if the injectors are still dripping fuel.

I don't know what to tell you about the smoke in the vents, but my fan switch gets really hot as well. I've taken it apart and cleaned the crud off the contacts a number of times. Still it likes to blow the fuse when on the highest setting, so I never use that setting anymore and no more problems. I think they are notorious for this.
Start with the air filter, you'll be surprised how easy it is. Good luck and keep us posted

[ninevolt]

I have taken off the doghouse and checked the air filter and it looks fairly clean. I banged it on a rail quite a few times to knock out any rocks and stuff and cleaned out the area under the air filter (which only had a few tiny rocks sitting under it). The spark plug wires all look really excellent; they definitely have no cracking but they could be a few years old for all I know. The engine has a layer of black crud all over it on several areas and has rusty areas, I guess this is expected for it's age. I took off the air filter enclosure top and watched the fuel injectors spray into the engine. I put my finger on both and its hard to tell if they are synchronized but they both definitely worked, I shined a flashlight to see the fuel coming from both of them. It seemed like the engine didn't let off the gas quick enough because when I step on it and let off, it takes it about a second to a half a second to seem to die down from getting the gas. I thought maybe the spring isn't pushing up my gas pedal hard enough or the lever attached to the cord running from the gas pedal was rusty and wasn't letting it move so I put some W.D.-40 on it. I haven't yet been brave enough to drive it like that, is it legal? The long bulgy metal things that go along the engine on either side of it right under the spark plugs look really rusty.

[landyacht318]

It would be bad only if you were parked on a dirt driveway and the engine fan were kicking up dust. I wouldn't drive it without the filter on. Don't drop anything into the throttle body. It could only be dangerous to run it with the cover off if your camshaft went flat and it were backfiring through the intake. You could not fail to notice this even with the cover on.

[ninevolt]

Oh yeah I edited the post and updated it, not sure if this sends a message or not about that. I saw both injectors appear to be working properly when I ran it with the air filter cover off.

[ninevolt]

I banged on the catalytic converter with a stick and I didn't hear anything moving around inside it, and then I banged on the aluminum shield thing and it looks like it's connected well but I could have sworn I used to hear rattling coming from there every once in a while right after I got it.

[ninevolt]

I drove it around with the doghouse off and the engine sounds like it makes a weird tick noise then the rpm's slow down a bit while it's idling. Could it be randomly misfiring or something?

[landyacht318]

Is it a ticking, like the fuel injectors or a tapping? You might be hearing the Idle actuator motor. It tries to keep it idleing above a certain rpm. I'll hear mine kick in when taking my foot from the gas and coasting. You can check if this is the noise your hearing by just turning the ignition on without starting it, and off. You'll hear the motor extend and retract and probably click.

More importantly does the engine Idle smoothly, rythmically. Does it shake or stumble much( more than 1/2 inch side to side?) Does it respond instantly to a little throttle. Does it make a clunk first and then rev higher.
If it does clunk it it called pinging and that can be remedied by higher octane fuel.

There are so many things which could contribute to the running rich/ black. Does there appear to be much varnish in the throttle body. If it is brownish, some of the vaccuum ports underneath could be so clogged with carbon that the Map sensor is getting a poor reading. Mine looked fine till I took it off and scraped out about 4 tablespoons of carbon. You could have a Vaccuum leak. Do you hear any hissing from the base of the throttle body?

You should get a Haynes or Chilton book for your model year and read through the maintenance and perform and tune up sections. Or you need to find a mechanic you can trust, if you feel perplexed by the engine and it's control systems. I can keep throwing out guesses as to possible problems, or things to look at, But I don't think it would accomplish much. I'm no expert and the term Novice might be a bit generous for you.
Also I'm not sure how much difference there is between our model years(mine's an '89) and some of my suggestions might not be relevant.
I wish you the best of luck and will respond to any questions if I feel I can answer them. Also keep in mind that your Van has many little contributing factors to the problem, and each thing you accomplish might help a little(like removing the throttle body and cleaning it fully). But if your cat converter's flow is blocked or heavily restricted, cleaning the TB wasn't neccessary but was still a good thing to do. The air filter might not look dirty, but a new one could flow 50% better. The list goes on. It is good to be able to cross thing off the list.
Once again, good luck.

[ninevolt]

Today I decided it would be a good idea to start cleaning off the engine since I've yet to put the doghouse back in place. I cleaned off the engine some then when I was cleaning off the top of the round air filter enclosure I noticed the hose that hooks to give air through it was partially disconnected so I plugged it back on there. This could have happened last time when I took the air filter out but I don't remember twisting the air filter compartment thing to the point that it would rip off the hose. That seemed to help it have more power and to stop making the black smoke so much. I need to get a clamp or something cause it has no clamp right there to hold the hoses connected. Also, I noticed that the hose going from the radiator thats about 4 inches in diameter that hooks up to the engine under the round air filter thing was leaking green stuff on top of my engine. I looked in the resovoir and the coolant was pretty much gone. This is the second radiator hose leak I've had in two months. I think I need to fix that or get a mechanic to do it for cheap. I am now wondering if the little wafts of smoke I saw coming up out of my gas gauge (from under the doghouse probably) could have been coming from the engine burning up from not having enough coolant? If that is the case why would it only happen when I had the high A/C on and not when I had the vent on? Hopefully my engine's not nearly destroyed now from not having coolant.

[landyacht318]

That hose that goes from your passenger side valve cover to the air filter is for pulling out any unburnt gasses from the valve cover Your engine's air intake pulles the gasses out. On the drivers side there is a smaller diameter hose that runs from the Valve cover to the throttlebody. This is called the positive crankcase ventilation valve, Or PCV valve. These are cheap 2-4 dollars and usually get replaced every tune up. You can check to see if your is still good by just pulling it out of the valve cover(when warm, easier) and seeing if it rattles when you shake it. If it rattles it's still good. Now start the engine with it off and stick your thumb over the hole. There should be a healthy vaccuum( sticks to your thumb). If no vaccuum you either have a cracked/split/broken vaccuum line, or the passageway in your throttle body is clogged with crud. This will definitly cause driveability issues. When the engine is running with the pcv off, feel is there is a lot of air coming from the valve cover. If there is, your valves are heavily worn and combustion gasses are getting past them. Not good.

Your upper radiator hose that is leaking is not that big a deal as long as you have not yet overheated the engine. Frequently they leak because it is difficult to tighten the hose clamp fully where it is located. If have a socket set with a 7 or 8 mm socket you can get that on the clamp and tighten it further. You simply cannot get enough torque on a screwdriver. A lot of people( myself included) use 2 clamps next to each other on this fitting( thermostat cover). If yours is like mine than right next to this big upper radiator hose is a smaller one. This one goes to the heater core and could also be the source of your leak. Same fix, as long as the hose itself is not faulty.

You said your resevoir was empty. When you engine is cold, remove the radiator cap and have a look inside. Hopefully you see green coolant, but if not , fill it with a 50/50 mix antifreeze and distilled h20, or just buy the pre diluted antifreeze. You should definitly do this before driving it any significant distance. If you can't tighten the radiator hoses rught away,you can fill up the resevoir nearly full(3/4) as a buffer, until you fix the leak.

Best of luck. Did you get a Haynes manual yet?

[ninevolt]

Thank you so much for your help so far, I haven't got a haynes manual yet but I know it would be useful for me to have a diagram to look at. I will keep you updated when I try to fix that radiator hose leak. The van used to put out black smoke when I pressed on the gas in park but now when I press the gas in park it doesnt put out black smoke since I connected the air hose thing. The weird thing is, when you let off the gas it gives a little puff of black smoke just before its done fully decreasing it's RPM's to idle speed. Is there any danger of too much suction if you stick your thumb on the pvc valve port? Also, I am not sure what the throttle body is, is that the thing with the injectors in it underneath the round black air filter holder?

[ninevolt]

I just went out and tried taking off the radiator cap cause I figured if that spews stuff out then if I take off the hose it will do the same thing so when I did it, green coolant came out the top of the radiator (1/4 of a cup worth) and I put it back on really quick so it would stop coming out. I guess it wasn't cool enough but why would the radiator be full of coolant if the resovoir is completely empty (actually I put some water in it because it was empty when I checked it)?

[landyacht318]

That's great that you got it to stop spewing black smoke. I'm no expert, I don't know exactly what the little puff of black smoke on decelleration is caused by. My guess is that you have a small vaccuum leak.
The Air filter attaches to the throttle body, you guessed right.
I wouldn't think re attaching the hose from the valve cover would do too much to the performance/driveability. It's really an emmision component. It sucks the vapors from the valve covers and re burns it to make it run cleaner.

There is no danger of too much suction at the PCV valve. The coolant resevoir is there just to capture the overflow from the radiator. When the fluid gets hot, it expands, putting the extra in the resevoir. When the engine and radiator cool, and the coolant contracts, the extra coolant in the resevoir gets pulled back in the radiator. Good thing you noticed the leak before you lost too much coolant.

Running the A/C will put more stress on your engine, make it run hotter, and increase the pressure of the coolant, causing your leak to increase. I am perplexed as to how smoke is coming out your fuel gaugeI'm guessing your doghouse doesn't fit tightly or was put on improperly. No air or steam from the engine compartment should make it inside the cab. When you re attach the dog house, make sure to get it in it's groove. There should be a rubber seal all the way around . Check the condition of the rubber and clean it with some armor all or like. If you have to use a lot of force to get the clamps back on it's a good sign you got it misaligned.

If I remember correctly you once wrote that an exhaust smell was getting into the vehicle. This misaligned doghouse could be the source, in combination with your previously disconnected valve cover hose allowing combustion gasses to enter the passenger compartment.
If this was your problem, you'll notice it is much quieter inside, once you get it installed correctly. It is also possible that after you drive the Van around a bit, the black puff of smoke on decelleration might clean up.
In one of your posts you mentioned your oil was black one month after an oil change, and the nimrod at the quickie lube swindle joint said you have a sludge problem. You should definitly change your oil, yourself, asap. Although the Oil is still okay in terms of lubrication. It can only absorb so much contaminents, and if it's black, it has absorbed all it can, and is now adding to your sludge problem, which will eventually kill your engine.

The reasons I say to change it yourself are:
1. You can let the pan drain overnight, and get out almost a quart more of dirty oil. Quickie places have the drain plug re installed(usually overtorqued) a minute after they take it out. Saves them time and new oil.
2. You control the quality of the filter and oil. The filter listed in the books for our vans is smaller that the filter on my dad's 1 cylinder lawn mower. I reccommend a Purolator premium plus #30001 or a Napa gold(Wix) 1515 for our 5.2L (318). It's twice the length of the standard filter, which means more filtration, less oil restriction, and more oil circulating. 3 Plusses.
I wouldn't trust a quikie lube moron to put the right grade of oil in.
3. You get to inspect the bottom of the catch pan when you return the oil to the 5 quart container for recycling. Lots of metal in there means time to sell, or rebuild. I'll cut open my filter and inspect the medium for peace of mind.
4. It's cheaper. The filter is less than 4$, 5 quarts of quality conventional oil is less than 15$.
5. You know it's done right.

I have some friends who swear by putting some transmission fluid in the oil 10 to 50 miles(no more) before an oil change. You can wipe your oil caked hands with a rag thats got a little tranny fluid on it and it removes the grease better than soap. It helps remove varnish from inside the engine.

Let me know how you make out!
Geoff

[ninevolt]

I unhooked the hose that appeared to be leaking coolant and tried pushing it on there harder it was hard to get it to go on further. The metal clamp thing was really not so hard to undo so I think it was loose, I gave it alot of clamp this time so it should be on there good. I was poking around the engine making sure stuff was plugged in and hoses were intact and plugged on good when I found a spark plug that was unhooked and covered in dirt connected to a tube, the spark plug was kind of stuck up in the area under the air filter enclosure but all my spark plugs were connected to the distributor and there are 8 of them so I was shocked when I saw the disconnected one but realized it was just used to plug up a tube. I don't know what the tube is but you can see where the tube is plugged into by looking at these pictures.

http://www.solarlogic.net/ninevolt/temp/vanprob1.jpg
http://www.solarlogic.net/ninevolt/temp/vanprob2.jpg
http://www.solarlogic.net/ninevolt/temp/vanprob3.jpg

[landyacht318]

That is a vaccuum line, not a spark plug wire. My engine also has one vaccuum line which is blocked off. Mine actually has a nice airtight rubber cap. I've never seen a sparkplug used like that before. Fishing weights yes, plugs for vaccuum lines, no. It does however say a lot about the previous owner. I'd replace it with a large enough to be tight machine screw. There should be a thinner vaccuum line which runs to the 3 solenoids located on the rear passenger side valve cover. These solenoids control the operation of your charcoal purge cannister(emission) Air pump(emissions) and EGR valve
(emissions) If your not in a state that checks for smog the previous owner might have disconnected them. Mine have a multitude of vaccuum lines running between themselves and the throttle body. I don't mess with them. I just make sure there are no loose ends. Any lines unconnected here can cause a small vaccuum leak.

In Photo# 3 I think the arrow is pointed at the rubber grommet where Oil filler tube connects. Mine only has one on the drivers side. The passenger side just has a screw on cap with a picture of an oil can. Mine had rotted out completly and I could not find a replacement. I wound up taking a gasket from one of the stock interior lights that came with the conversion package.

It's not a life or death problem but it does help the pcv system work as designed, and keeps any debris from getting into the valve covers. In California and probably some other states with smog checks this could, if noticed , cause you to fail the inspection..

I've actually just removed all the stock conversion interior lights (switching to LED's) and have an extra grommet to spare. Let me know.

[Chump]

When you fill the overflow tank, do so when engine is cold. Look on the tank and it should be marked COLD towards the bottom of the tank and HOT towards the top of the tank. The hot coolant overflows from the radiator when the engine is turned off, as the radiator cools it sucks the coolant back out of the tank and into the radiator. So it is possible to have a full radiator and an empty tank. Fill the tank when cold and only to the COLD mark. If you have a coolant leak at one of the hoses, replace the hose and both clamps. the Throttle Body is marked Holley and sits below the air cleaner and on top of the intake manifold. Picture #3 may be an emissions control hose/valve.

[DannyDT]

I just went out and tried taking off the radiator cap cause I figured if that spews stuff out then if I take off the hose it will do the same thing so when I did it, green coolant came out the top of the radiator (1/4 of a cup worth) and I put it back on really quick so it would stop coming out. I guess it wasn't cool enough but why would the radiator be full of coolant if the resovoir is completely empty (actually I put some water in it because it was empty when I checked it)?

I know this is an old thread, but for those that dont' know any better,
you can squeeze the upper radiator hose to see if there is pressure or not.

I highly recommend you do, because you could burn yourself if you don't.

[surforlife1]

I have a 1990 B 250 with a V six 3 speed auto,my blew black smoke after i tuned it up , found out i left a vacum hose off the carb,,,Hey i know what a knuckle head,,Oh can any help Im trying to improve my mpg.I was thinking on taller gears for the rear end,,,I think i have 3.5 now ,at highway speeds i get 10,mpg at 70 mph.Any advice?

[alloro]

Any advice?

Do 65. ;)

10 mpg is really on the low side for the highway. You should easily be getting 14-15 mpg. Sounds like something is drastically wrong.