Hi everyone, new here. Recently bought a 92 b2600i 4x4 5 speed and am now having some running issues. It seems to miss at around 3000 rpm after a few min of shifting past 3k then it becomes boggy at all throttle positions and speeds for a few kms then will slowly come back to life. Starts and idles fine.
Set timing to 5-6 def Btdc, and set idle at 750 while jumped. New plugs
It also will struggle to idle while pressing the clutch at about 2500 rpm coming to a stop. It dips below the 750 rpm and catches itself
tomorow I will put a fuel pressure gauge on it as the old filter was absolutely full of what looked like rust and I ordered a new one but been using smaller clear plastic filters past few days and cleaning them daily or changing them *** they continue to get full of small rust particles. Any advice would be appreciated and some direction where to go next after fuel pressure checks out if it does.

cheers and thanks for any input u guys may have

 

Also plugs shortly after changing them

Plugs shortly after changing. Def not running rich

 

Welcome Meandmyz,

It sounds like you have multiple issues going on, but I do know of one known issue that more than likely needs to be addressed with your truck FIRST.

The Clutch Switch......

There is a small switch that looks & operates similar to a brake light switch on a brake pedal.......except this Clutch Switch is on the CLUTCH Pedal. When this switch goes bad (and they always do!) there will be noticeable RPM changes in the idle when the clutch is depressed. It is wired into the idle circuit of the ECU somehow......a friend of mine knows way more about it than I do, but I have experienced it first hand myself.

So, crawl under the dash where your clutch pedal is at, and you will see a small switch, where the plunger is (I'm going on memory here!) supposed to be depressed when you DO NOT press the Clutch Pedal, and extended when you actually depress the Clutch Pedal.......when the SWITCH plunger is extended, I believe it is supposed to make the electrical contact inside of it, and if the plastic plunger OR the return spring for the plunger is broken, it will not operate as it should, naturally......and it will cause idling issues.

My money is on the fact that your Clutch Switch IS broken!

I do have some pictures of this switch that I will post here shortly.......and I hope than I am correct on the way it is supposed to operate......if not, I will edit my post to correct it, but as of now I'm going off of my memory....and I'm OLD!!

 

OK......here are some pics of 2 broken Clutch Switches.......one switch has a broken plastic plunger......the other one has a broken return spring! I disassembled both of them and by swapping the internal parts around, I made one GOOD Clutch Switch!













After swapping the parts around, I made a good working switch......after I re-assembled it of course!



If your plunger is not broken, but the spring is, you can probably find a new spring for it at the hardware store also.....



Like a lot of these original Mazda parts.....you can take them apart and fix the issues they have and return the part back into service again.......on the CHEAP!

 

Thanks for the info I will def look at that this weekend while I have a few things to address….
first thing I did tonight after work was through a fuel pressure gauge on it. Had a whopping 25 psi at idle. I then jumped the fuel pump yellow plug and had a whopping 30 psi. And it didn’t hold pressure either. So I then pinched off the return line for
giggles to see what it could make and I got a solid 43 psi.
I had to now drop the tank and dig deeper….. well here are some pics. I got a new pump but can’t get a strainer, tank or sending u it so I am gonna clean the tank, strainer and put it back together for
now until I get parts





any ideas for removal of the ground off screws or some new holes for now until I can get a new tank and sending unit

i geuss the 30 yr old truck has been neglected over the yrs.

 

Well guys wanted to give an update. After changing tank pump, pickup, and rebuilding my sending unit I haven’t had any issue for a few mnths. Was only a matter of fuel pressure. Moral of the story is don’t change a computer for lack of power/stalling do the proper checks. Cheers guys and enjoy those old Mazdas as much as me