Hi folks, I am hoping to get advice on the wife's 1989 B2200. It was running normally last year but starting to burn excessive oil so I changed the engine to a good used one. I was very careful to label every vacuum hose and electrical wire with electrician's number tape, as there are lots of them.

I reused the old carburetor. Since the swap, the engine has run rich and idles high all the time. It is getting only half the mileage it used to get. The choke plate on the carb is opening fully when the engine is warm. It seems like the computer is opening some auxilliary fuel system all the time.

In searching the internet I have found advice on how to retrieve codes from the check engine light, but this vehicle does not have one (Canada only delete, it seems). So I can't get codes that way.

I bought the genuine Mazda shop manual which says to use (of course) the genuine Mazda scan tool which seems to be unavailable on ebay etc. The generic scan tools cover "most imports", meaning not Mazda!

Anyhow, hopefully some clever B2200 enthusiasts can give me a few tips.

 

You will not likely find much here, you truck is a legacy Mazda model. You would have better luck on a Mazda forum. The folks on this site will try to be as helpful as they can, but the Ford Ranger and the Mazda B series did not become the same thing till the 1994 model year.

Someone here may have experience with your model, but on a dedicated Mazda truck forum, you will probably find more people familiar with your setup.

 

I think you are right Tyranitar, I was just hoping to avoid having to join another site just for this vehicle.

 

Have you looked to the carb float setting, or fuel injector if it's a throttle body injected setup???

I'm thinking maybe if it has a real carb as you posted, the ethanol in E-10 has messed with it's seals or the float has a hole in it, or some other way it got messed with in the engine swap & isn't properly controlling the float bowl fuel level.

On a carb, the float drop & rise setting must be properly adjusted to prevent too low a float bowl fuel level & lean mixture, or an over full bowl, or one in which the float rise setting is too high, or the float seal is damaged, such that it doesn't fully shut fuel flow into the bowl off, thus it'll over fill & spill out the bowl vent/s into the venturi & cause a rich mixture.

Or maybe dirt, or sediment in the bottom of the float bowl got stirred up from handling & has cloged something up in the carb, or fuel injector if it has a throttle body/injector set up & is causing the injector pintail to leak.

SO, with the Mazda shop manual, you should be able to dive in there & check out, adjust & clean things up, no matter what system you have.

Edit: Put a fuel pressure check on the list.

The computer & engine would need to be matched too.

 

Also check that, when the new engine was fitted, the fuel return line was not kinked/pinched.

 

During the engine swap I did take the carb cover off to give it a quick clean, and all seemed good inside. The level was right in the middle of the glass window then. I agree that a high float level would cause a rich condition, but since this happened when I swapped engines and the idle speed is also increased, it is probably due to something else.

The comment about the computer and engine needing to be matched seems like a possible lead, as I don't know what exactly the replacement engine year is. However, since I used the original carb I would think that the computer doesn't really know what the long block is.

I did check the oxygen sensor and engine temperature sensors which gave proper readings when tested with a multimeter. Since I had two of everything I tried swapping the sensors with no improvement.

I'm thinking that I just need some way to probe the primitive brain of the truck to get a code but can't figure a way to do so.

 

OK, good feedback, so it is equipped with a real carb.

Is the fuel pressure in spec & the carb float bowl fuel level still in the middle of the sight glass????

How is the MAP. or MAF sensor output to the computer???

Is the replacement engine the same size/displacement as the old engine????

 

Beanscoot, when you made the swap did the engine you put in come with an intake manifold? If so, was it removed at any time and were the gaskets replaced with new ones and torqued properly? Even if the manifold that came with it didn't get removed you might want to make sure the gaskets are in good condition and the manifold bolts are tight, to avoid vacuum leaks. If it's idling too high you may have unwanted air entering the system. You might want to check for any signs of a split or cracked gasket around the base of the carb and the riser or spacer under the carb (if it has one) where it meets the manifold. A thick good quality gasket will seal better than a thin gasket. Some times I've had to make one from gasket paper. Also check the gaskets where the manifold fits to the head. Make sure all the vacuum plugs and or caps are tight and in good condition. Check vacuum hoses for cracks or breaks and tightness at the fitting they attach to, including the one going to the brake booster. And you may need to get into the carb like Pawpaw suggested to check its condition. Let us know how it goes.

 

Thanks for all those tips. I did try to check the float level once again, but even with an inspection mirror I cannot see it due to all the junk in the way. Although I doubt it's a high level problem since it was okay when I checked it at swap time and even if it were high, it would not cause a very high idle, just a very rich idle.

I am using the intake that stayed with the replacement engine. I do not know for absolute sure if it is a 2200, how can I tell if it is a 2000? And could this really cause a drop in mileage by half?

I don't know if this engine has MAF or MAP sensors. I tried both the original and fuel pump that came with the replacement engine which made no difference. The return line seems clear when I blow through it.

I'll check for vacuum leaks carefully. I thought this would, if anything, make it run lean, but on second thought I can see that this might confuse the "computer" and make it overcompensate to too rich.

As for being equipped with a "real carb", well that's debatable as it's a vacuum/electronic controlled monstrosity. However, the thread title is "Carbed B2200 running rich".

 

When I said "real carb", I was thinking a float bowl carb, as oppsed to a throttle body injection set up, that some folks confuse with a carb.

On the engine size difference, I was thinking maybe if the computer program is set up for one displacement engine & it's used with another, the computer might get confused about a number of things having to do with fuel trim, ect,

This might be made worse if it has a MAP sensor, rather than a MAF sensor, that drectly measures engine intake air flow volume.

Did you get the O2 sensor hooked up & are you certain it's working???? Just a whiff of coolant in the exhaust, is enough to take one out.

 

On the scantool question.
The info I have with my Actron CP-9150 scan tool kit, says that Mazda between 88-95 used 6 pin, or 17 pin MECS (Mazda Electronic Control System) diagnostic connectors.

SO, it seems that at least Actron makes a scantool & MECS connector adapters, that would let you hook up a scantool like the Actron CP-9145 & scan for codes, as well as read live sensor PID's to the computer & computer outputs to it's actuators.

SO, if you have, or know someone with the Actron CP-9150 kit that has the CP-9145 scantool & the MECS adapter connector cable in it, or if you know someone that has a CP-9145 scantool, you could order the 6, or 17 pin MECS adapter cable for the CP-9145 scantool from Actron & have a combo that would pull your codes & monitor live computer feeds & that sure would make your trouble shoot much easier.

The Actron 6 pin MECS connector adapter is P/N CP-9131. The 17 pin MECS connector adapter is P/N CP-9128

More possibilities for consideration.

 

Pawpaw states it used MECS. The 95 Probe v6 uses a MECS system with a multiple pin connector. You use a paper clip to jumper two of the connectors, and it will blink out the code on the CEL, which you don't have. I think it also pumped out the blinks on two of the other connectors, as the 'scan tool' just connected to the multi-pin connector, and jumpered one connector, got power and ground, and blinked out the code from two other pins[volts + ground]. You can use a VOM or test light to look for the voltage pulses that will be present. I suggest you search the web for Probe code readings.
I don't know of any carb systems that used a MAF nor a MAP, but I don't know them all. Are you positive that you put all the carb spacers and stuff back on the new engine? Is it possible the linkage might be 'flipped' in part, where a link has passed its normal range of motion and gone on to working in the opposite direction? Or could the linkage be interfering with other engine parts? A carb will only give high idle if the throttle plate is held open. Some engines had a full-close position on the throttle when the key was off, and an electric solenoid to prop the throttle open with the key on, after you pressed the gas pedal. Not enough solenoid to open the throttle, but enough strength to keep it open until the key was turned off. It prevented run-on when the ignition was turned off.
I have had bad throttle plate bushings that bled extra air, and you could not get the idle down because it would not run unless you had the idle adjustments way out because of all the extra air. Have you checked your throttle plate bushings for slop?
All the above says either a linkage or throttle plate problem for the high idle. The only electronic controls for carbs that I know of were to move metering rods in or out of a jet to vary the amount of fuel flowed. If yours has one of those, it could affect the fuel mileage significantly.
Last thought is the transmission linkage. If you have an automatic, the kickdown rod may be interfering with full throttle plate closure.
tom

 

I like tomw's ideas.

 

Thanks, Tomw, the truck is a standard transmission. I don't think it's a throttle bushing issue since it happened suddenly.
When reading the shop manual I did find that there was some electrically controlled metering device in the carburetor that added extra fuel when decelerating with the throttle closed, I thought maybe the computer is confused and holding that thing open or a similar situation.
It is such a pain in the neck to work on the carb because so many vacuum hoses have to be removed just to get to see the carb, and then of course it will be running wrong because the hoses are off.

 

Adding extra fuel when the throttle is closed is generally not a good idea. You will likely get backfires out the exhaust when the extra fuel finds some extra air in the muffler and a hot spot... Generally, the fuel is discontinued when there is a throttle closed - decelerate condition. Let the engine 'run' on pure air as it decelerates, thus preventing the backfire, saving a bit of gas, and cutting emissions of unburned hydrocarbons.
My sister had a Capri with a 2.3 and California emission controls back when. It had a modified Weber 2 bbl, like on the Mustang II and Pinto of the mid 70's, that had a metering rod that was moved by a solenoid. I *think* it had a throttle plate solenoid that kept the throttle open a bit on deceleration. When you took your foot off the throttle, the car did NOT slow down for a few seconds {define "few"}, and there was little to no compression braking for some period of time. That tactic cut emissions. Was not as much fun to drive, either.
If any of the temp sensors or vacuum delay valves or temperature operated vacuum valves were carried over from the new engine, rather than the old, you might want to consider testing them for proper operation. In other words, you may have imported your problem rather than created it.
tom