My truck has a problem with stalling after it warms up, and I can't find the true cause. It will usually run strong for 10 minutes or so, and then start losing power and quitting altogether. Occasionally it will start again...sometimes not. Plugs, wires, cap & rotor are all new. Seemed like a fuel delivery problem. Fuel pump was replaced, and carb was swapped with a newer used model. No leaks in fuel lines. Carb gasket replaced. Looking for vacuum leaks. Still no clues.

Is there an electrical or computer problem that could occur after the engine warms up that would affect how the fuel is being metered? Or maybe something as simple as the coil going bad after it warms up?

Thanks for any help!
Steve

If it's losing power after it's warmed up, then you may want to have the two catalytic converters checked out first. That seems to pretty common on those trucks.

I have a 91 with similar problem. Took it to a Japanese Car Specialist and they inspected it for 5 hours without any idea, except giving me a bill for the time.

I noticed that the engine runs rich and will give out black smoke. The chek engine light also comes up.

Since it gets worst when warm, I suspected anything thermo. I have been able to keep the car idling very well when cold, and have to give it some gas to keep it running at warm. The only thing I have done so far is to clear the IAC. With 100K+ miles, I found that the actuator cannot function properly and get stuck. It is actually a stepping motor, and when I turn the key on without starting the engine, I can feel the stepping motor trying to do its work. After taking it apart and cleaning the inside of it, I did the same test and found that the actuator will actually move smoothly when the key is turned on.

After the cleaning, the pickup will idle nicely when cold, but not after it is warm. I suspect a faulty Oxygen sensor, because it can mislead the computer to put more fuel into the engine, which can stall the engine by wetting the spart plug.

I have purchased an Oxygen sensor and will try to install it tomorrow. Will let you know the result.

If you have any other symptom on your pickup, I may be able to point to other stuff.

It looks like my fuel problems are solved for now. A carb from an 89 with only 100K on it showed up at the junk yard (fresh meat!). It did the trick.

Thanks for the responses, Eric & Henry. I'll keep an eye on it when things start running rich. I did check for flow through the converters, which was fine.

I found a way to read the ECM before replacing the O2 sensor. The code indicates problem with water temp sensor, air temp sensor, throttle position sensor, etc. but not the O2 sensor. So I did not perform the replacement of the O2 sensor.

I had a Digital Multimeter and was able to measure the throttle position sensor, it seems to work fine. The temp gauage works OK. so I suspect the coolant temp sensor is also functioning normally. It seems that I have a faulty ECM after all.

THERE IS 3 SOLNOIDS ON THE PASS FENDER UNDER THE HOOD ONE PURGES IT FUMES THAT CAUSE VAPOR LOCK. 65$CAN AND THERE A MUST.

What is the mileage on you truck. And how it dies. Engine slowly die out or a clean cut. If slowly die out, it could be fuel problom. if a clean cut die out, it is electrical. If it is fuel, it stall out on idle, low speed or hi speed. If electrical die out, does it restart after engine cool down? It is can restart after cool down, it could be the ignitor inside the dist.

I think it may be useful for others to look into this experience. I have finally diagnosed that the engine trouble is related to the ECM. Or the Engine Control Computer Module. AV-PRO COMPAMY had it re-manufacturered for $175. Almost one tenth of a new unit.

To see if you have the same problem. Remove the computer, open it up and see if you find some gluey stuff. That is the result of a leaky Electrotic Capacitor mixed with the moisture seal on the computer. It eats into the circuit and messes everything up that it touches. My computer gives me error on all the temp sensor, including water, air, as well as throttle position. If you have more than one sensor going wrong at the same time with the check engine light on, you might want to open up the computer and check it out.

It takes years for this to go bad in my case. The trunk original develops a very strange symptom. It will idle well when cold or hot. But not after a shutdown of 30 minutes or so. No one seems to know what it is, including the dealer. This problem also gone with the repaired computer.

For this particular kind of computer problem, the computer will not smell like it is burned. So the only way to check it out is to open up the box and look for it yourself.

If you need to read the computer for a 91 Mazda B2200, it is very simple. Locate a green connector in your engine compartment. It should be right in front of the firewall on the passenger side. Along with it are two more connectors, one with six slots but only three contacts, and the third one should be yellow with two contacts. If you find this, ground the single green one, and then turn the ignition to regular driving position. DO NOT START THE ENGINE!. You will then be able to read the error code from your computer. A long "ON" means 10. The number 12 will then be a long ON followed by two short ones. Multiple error codes are spaced out with long OFF period. And the entire sequence will keep on repeating until you turn your key off.

I got most of the error code from Chilton's Guide on Engine Code. This set of code leads me to return my oxygen sensor before installing it. And it keep my repair cost down to just the engine computer. If you have your check engine light on, make sure you read your code before purchasing any spare parts.

Well, my problem with the stalling while driving has gone away, but I do need some carb adjustments. I'm beginning to believe that the original problem might have been ice in the fuel system. The truck had been sitting outside at the shop for a few days when the temp dropped well below freezing at night, and I didn't have any isopropyl in the tank at the time.

The running has smoothed out considerably after about 1 full tank of good freeze-proof fuel. But if I let it warm up for about 5-10 min while I'm in the house, it will be racing something fierce when I come out. After kicking it down, it idles so low that it's constantly on the verge of dying. I'm only getting about 14 mpg, which really sucks for a B2000...even with 124K miles! Unfortunately, this truck is usually only taken on very short trips (5 min) or up some pretty steep hills, so I don't know what sort of mileage it could get on the open road since the carb swap. I used to get approx 19mpg with my normal driving.

My check engine light is NOT on, but I'm wondering if I have a bad O2 sensor that's causing me to run too rich. There's no black smoke, but when it's cold, I can smell gas in the exhaust. Would any codes show up in the ECM if the check engine light is NOT on? BTW, the air filter is new.

We went with an electric fuel pump when 2 different new mechanical pumps were delivering very low pressure. I'm wondering if the cam lobes are just plain worn down and perhaps failing to open the valves as far as they should. Might this account for the bad fuel mileage, or would I have bad acceleration problems as well?

Who thinks the problem is just a few carb screws in need of adjustment?

The check engine light will not come on if the problem is minor. Since you have a carb. Not fuel injection, I don't think the O2 sensor will cause you to run rich, as fuel is delivered via the carb which works off vacuum in the intake manufold and throttle position.

Another source may be your choke. My 91 B2200 has a very sticky choke to the point that it gets stucked. If the choke is stucked close, it will cause the engine to race as it gives too much fuel. Once it is released, your idle setting on the engine may be too low. Try warming it up, did what you do to bring down the rpm, and then adjust idle. May be this will help.

I had the same problem, it is your sensors and you pcvc valve. You may also look into you carb performance, take off air filter and ceal out your carb and area, your problem is definetly due to oxygen deprevation, causing the stalling in your engine

The thing that could be causing your truck to die is the alternater is not charging.You might have to replace it. I had a 92 ford ranger that was doing the same thing and thats all it took to get it going again. Hope everything works out for ya

David

My '86 B2000 5 speed extended cab pickup has been acting up recently. After driving for about 15 minutes, it begins to sputter and struggles to remain running. When it does stall, I have to wait about 5 or 10 minutes and then its up and running again. I replaced the ignition coil, distributor cap, spark plug wires, fuel pump (mechanical type), fuel filter and the alternator after I bought the truck and had to put in a head gasket. I also overhauled the carburetor (new float assembly and air horn gasket only) while swapping head gaskets. It seems to act up after driving at higher speeds, or after driving at least 15 minutes. Sometimes it doesn't act up for quite a while, but lately it's been stalling out more frequently. I drove it for about 6 months with no problems, then the stalling started recently in the fall. Any ideas? Thanks.