Hello
It’s my child’s auto.
It quit running and I diagnosed no fuel by dry plugs. I changed the fuel filter - lots of gunk came out when i blew it out, Then she ran like she hasn’t run in years.. sounded great. 10 mins later, ran really rough then next day wouldn’t start.

i pulled new filter. Fuel in it was clean. Ran the pump and fuel flowed well it seemed through the filter… but spark plugs are dry again.

i also siphoned some fuel out of the bottom of the tank.. no obvious gunk or rust.

Fuel regulator? What would stop flow of fuel to cylinders after the filter?

thank you in advance for any ideas/offerings

 

Welcome to the forum

 

There is a known issue with the EFI Mazda trucks of that era.......both the B2200 EFI and the B2600i EFI trucks. There are two larger ORIGINAL capacitors on the ECU board that will leak acid and etch the board and cause corrosion. The corrosion can eventually eat through the Humiseal protectant and then the copper traces on the ECU board. Because of the ECU orientation when bolted to the passenger side kick panel area, the acid runs down (gravity induced) the ECU board and attacks some of the injector circuitry and will cause fuel delivery issues.

You can disconnect the truck battery, remove the right side kick panel cover, remove the ECU, and open the case to have a look at the board. Here is a couple of pictures of what a good B2600i ECU board (very similar to the B2200 board) looks like......you can see the original red and the original black capacitors at the top middle portion of the board:





Here is a B2600i ECU board that had corrosion damage and was "repaired" by a repair shop, I guess.....

 

Thanks MeB
ill take a close look at that tomorrow.

 

I pulled the ECU
It looks fine to me.
here are a couple pics…

so I think I’m on to figuring if the fuel regulator can stop fuel. It seems when it fails it usually allows too much fuel but I don’t know where else to go here.

 

Doesn't look so good to me ! See red oval.

 

Wow. Eagle eye!
thats great
thank you Cusser

i cleaned the board up with a de-ox and light nylon brush.
any suggestion on how one figures out what to replace that cooked resistor with? I looked at the pic of the clean /good board at the top of the posting and it’s not revealing enough of that resistor to ID it.

in meantime, I confirmed pvc is working and pulled the fuel regulator off the fuel rail. There was pressure so it’s getting past the regulator so it seems perhaps the injectors aren’t firing fuel?

After that work, with a freshly charged battery she would crank and catch a bit which is better than previous but still no start.

i forgot to mention that after the fuel filter replace, I dumped a can of Seafoam into the tank… might I have caused trouble with that or is it coincidental?

 

I'm not familiar-enough with B2600i to answer any of your questions.

 

I think the component Cusser circled (2 tone bead) was a legend for a diode?

 

Yep, ceramic diode

https://forum.digikey.com/t/help-ide...ad-diode/14904