1992 EFI B2200 - No power, runs rich

Hi! This is my first post here. I've spent the past two weeks trying to solve an engine problem and haven't made much headway so far. I've spent a lot of time searching the web and have acquired a Mitchell's manual.

My truck is a 1992 B2200 (EFI - fuel injected) with 149,000 kms (92,584 miles)

At first, power would cut out - the gas pedal would be unresponsive and the engine would stall randomly (when driving uphill, downhill, or on flat ground). I could idle the vehicle for about a minute and the power would return and drive fine though... until power cut out again.

That was then. Currently, it starts and idles okay but doesn't respond to throttle input. When warmed up, it runs rich, producing black smoke out the exhaust and has no power when trying to drive it - I can barely get it moving. The only way I can move it is to put it in first gear or reverse and drive it with the clutch half-out (not using the gas pedal at all).

The check-engine light (MIL) never lit up and the truck displays no self-diagnostic codes. The MIL is not burnt out and the rest of the indicator lights are also good.

So far, I have:
-checked fluid levels
-added 3/4 tank of ethanol-based gasoline and gas line antifreeze (suspected moisture in tank)
-checked fuel pressure before and after fuel filter and got specified readings
-checked that fuel injectors hold pressure and don't leak down
-checked air filter
-checked, cleaned out, and later replaced mass air flow sensor
-pressure-tested snorkel (between mass air flow sensor) and throttle body
-cleaned throttle body with carb cleaner
-checked for spark at plugs and at coil
-replaced blackened spark plugs and set gap according to manual (they were BLACK)
-checked and cleaned O2 sensor (which was also BLACK)
-checked coolant temperature sensor
-checked air thermal sensor (aka air charge temperature sensor)
-checked vacuum hoses for leaks
-checked that the catalytic converter heats up

I'm hoping that this is something really simple (maybe an oversight). Any suggestions or similar experiences and solutions would be appreicated.

Thanks in advance,
Chris

The symptoms that you are mentioning could be due to a weak coil or a loose/corroded ground for the block. These would be my next two areas of inspection at this point. A spark from the coil does not always mean a strong spark. The epoxies that they used back then were not the best and voltage would leak out over time through micro cracks.

Hi emjay,

Thanks for the response. Yesterday, I finally got it running and the culprit was a faulty Power Control Module (aka ECU). Luckily, I found a local guy who repaired it for less than $200, as they cost close to $1000 from Mazda. Apparently, the capacitors leak over time, causing the fault.

Chris

lol, nice find then dude. yeah these ecus are hard to come by, the old capacitors had some sort of acid in them that ate away at the PCBs. An even bigger problem for the B2600s.

i think i have the same problem..

when you give it gas, did the engine just bog out entirely? because i hate this issue, it would bog out for a minute and then it would be fine again.. now, the engine doesnt event let me give it any gas

pretty common problem (the ecu taking a crap), but its good to hear the syptoms! usually just 'the truck doesnt run at all!'

this should be sticky'd for easy finding.

Yup. That's the problem I had. Getting the computer repaired did the trick. For a while it was intermittent, but got worse over time until I just could not drive it at all.

This is a link to the Craigslist ad that I found and used.

Anyone have an ECU that I can borrow really quickly to see if this fixes my issue? I think I have this problem right now and don't want to drop $200 on it if it's not going to fix my problem... =\

Hopefully you can find someone locally, but the fellow who repaired my ECU was willing to test it out on his truck first (plugged my bad ECU into his truck) before doing any work.

I have a 92 mazda b2200 aswell with this same issue. im in the Edmonton alberta area curious if anyone knows anyone around here or even that I can mail the ecu too to get repaired. I would really appreciate this. thanks