1990 Mazda b2600 Engine missing

Hi 90mazda,


Thank you for the donation.

If the igniter is bad, you would not be able to start the engine so that should not be the cause.

The more likely cause would be a bad injector that is stuck open. Try to determine which cylinder is not working correctly by pulling out the spark plug wires and noting which cylinder causes the least change in idling speed.

I determined that cylinder 2 and 4 are not firing. Since I replaced the spark plugs, wires, coil, distributor cap, and rotor and the two cylinder have a spark at those two plug wires, do you have any suggestions?

Get a compression test done to verify if they are within specs.

If compression is within specs, swap the injectors between the 2 good ones and retest if it is still # 2 and 4 that is misfiring.

i have exact problem,not hitting on 2nd and 4th cylinder.have checked cam shaft--llifters ,will check compresson in the morning.this is making me crazy.if i pull wire to second plug out of distributor i get alot of arcing from the wire that runs to the coil on fender of the truck. this is a mazda b2600i is there 2 fuses or 1 fuse for the injectors and where is it or they located?

All four injectors are powered from the same source, via the FI main relay. Cylinder 1 and 4 works in tandem with a common ground at ECU. Cylinders 2 and 3 is another pair. That eliminates the possibility of power supply failure and you shoulc check the voltage at cylinder 2 and 4 to determine if it is a broken circuit.

Recheck the ground circuits between the engine and body, it could be insufficient and adding another might help.

i had a lifelong mazda man look at it today.he said computer is the problem.i hate to spend several hundred on something im not really needing.

If it is the computer, then either you replace it or you try using a piggy back. Connect the 1 and 4 cylinder injector ground circuit to the computer. Likewise with 2 and 3.

For a cheaper alternative, you can try getting a reman.

what is the cheaper way or how do i piggyback my injectors?

Remanufactured computers are cheaper than new unit and locally you should be able to source them. Check with your local parts store for that.

After rechecking through the wiring diagram, I realised I made a mistake previously. For earlier models, the injectors would work in tandem, injector # 1 and # 4 are linked together whereas Injector # 2 and # 3 are a pair. This would rule out the computer as the culprit. If it is, you would not be able to start.

At the injectors, unplug all the connectors and test the Black/Yellow wire for battery voltage with ignition switch on.

If voltage is not available at #2 and #4, check for broken wires between the wires.

If battery voltage is available, test for continuity between the Light Green/Black wire of injector # 1 and # 4. If continuity is not found, you have a break in the wire and reconnecting them would work.

Likewise, perform same task with Light Green/Red wire between injector #2 and #3.

By the way have you tested and confirmed that the injectors are good?

wire were tested at injectors.are you saying its not the computer?injectors do work when switched to another cyclinder.not sure what you are telling me

test for continuity -----explain how to make tkis test will find a test light

i connect a test light to 4 th injector with key switched to on i have power to both wires on the 4th and 1 st injector. now what?

test for continuity between the Light Green/Black wire of injector # 1 and # 4. If continuity is not found, you have a break in the wire and reconnecting them would work.

i have power to injectors on both wires explain what i need to do next

For continuity test, you need an ohmmeter. If you do not have the ohmmeter, disconnect the ECU harness.

Attach the test lamp to Lt Green/Black wire of injector # 1 and battery voltage. Use another wire to ground the Lt Green/Black wire of # 4. If test lamp lights up, the wire is good.

i disconnect cpu from harness---i touch test light to 1 st injector---with i end --the other end of tester goes to hot on battery ----then jumper a small wire from 4th injector wire and touch it to ground correct yes or no sorry im so slow at this

Yes, that is correct.

i disconnected cpu=i pushed point of tester in plug for 1st injector as soon as i touched other end of tester to hot light came on.i must be doing something wrong-----tester= 2 wires--1 to plug of injector---other end to positive post on battery---yes or no----light comes on and stays on in both holes on connector of injector.

Which wire did you test? The one with battery voltage when igniton is on would also light up if battery voltage is applied with a test lamp connected, unless the ignition switch is turned on.

Did you unplug all the injectors?

this is what i did- disconect cpu inside truck -- unpluged 1 and 4 injectors----connected tester to positive on battery---switch is turned off-----connected other end of tester to harness,1st injector green wire light comes on i never even get to the 4th injector light just stays on

Remove from 1st and try with 4th injectr. What is the result?

i unpluged all injectors ---i have power on 1 side of plug other side of wire has nothing even when grouned with 4 injector wire where to go next? light does not come on with tester--is wire bad?

Perform the test I posted earlier with the wire that has nothing when grounded between 1st and 4th, 2nd and 3rd.

i cant get to the 2nd and 3rd injectors good enought to test they are behind everything i retried several times between 1and 4 and 4 and 1 with nothing on the one side.could a ground cable be the blame --i see a couple wires grounded to intake manifold i guess ---should i remove the short wire harness for truck to get to it easier? oh yea thanks for all this

If 1 and 4 does not hav continuity, try using a jumper between them and retest if the 4th injector works.

do i connect all iijectors back up and plug in cpu after connecting a jumper from 1 to 4 befor ei try to start motor or how do you mean test with jumper

Yes, reconnect all and start vehicle to test. If cylinder 4 starts to work, then you know the ground wire is faulty.

after a few test i tried to ground 4 and check from 2 and i am getting current --its 1 and 3 and 2 and 4 so now i am lost for sure--power is right if i test 2 and 4 i ground 4 and test 2 with light working so not the ground could distrubitor keep it from fireing injectors?---i did disconnect all injectors and cpu tested 1to 4 nothing tested 2 to 4 with a responce when grounded to frame light worked

ok since it seems 1 and 3 and 2 and 4 are sets and 2 and 4 both arent working are we now looking at a bad cpu?

You got it wrong. 1 and 4 is a set. 2 and 3 is the other set.

You were supposed to test 1 with 4 and 2 with 3.

i looked at wires tthe second and 4 th injectors have the same wire color the 1st and 3 have same color wires.if i ground the 4th injector and test the second i get a light when i remove ground on 4 the light goes out.the same when i ground 3 and test 1 i get light when i remove ground from 3 light goes out when i test 1 to 4 i get nothing--

Light Green/Red wire these are the wirecolor for 1 st cylinder also same color on 3rd cylinder

Mazda four cylinder engine error codes 1989-1994
After the engine has been operated and the key subsequently shut off, it is not necessary to restart the engine to retrieve the error codes. This is true as long as the storage battery has remained connected to the truck.

Make sure the ignition is in the "off" position. On the drivers side under the hood, on the MPV at the junction of the grill and fender there should be located a single wire as part of a small bundle of connectors. On the pickup the connector is near the firewall on the passengers side. The singe wire will have a single green connector. This wire/connector should be connected to the chassis of the truck to allow the ecm to flash the error codes.

Get in the drivers seat and turn the key to the "on" position. The check engine light should come on for a few seconds and then go out. If there are any error codes stored, the light will start displaying the codes at this time. A long flash will be for a "10" short flash for "1", eg. code "25" will be two long followed by five short flashes. The ecm will continue to flash until all codes are displayed and then start the sequence again.



did nothing for me------------and yes there is a single green plug on passenger side as stated in directions

If 1 and 3 have the same wire color, then they have been swapped.

I have been telling you that cylinder 1 and 4 works in tandem. Likewise cylinder 2 and 3 are in the same circuit. If you do not wish to accept, then I have nothing more to say.

i do need the help.only trying to convay what i am seeing.i connected 1 to a test light with cpu unpluged and injectors unpluged and ground 4 with no result--if i ground 3 the light comes on if i ground 2 light does not come on------

at distubitor the plug that plugs into side if distrubitor.4 wires look alot those on injectors----i tested with switch on 3 wires showed power 1 none--the 3rd wire showed bright lite on tester the 2 nd 1st shows but very dim connector looks very bad

If grounding #2 and # 4 works, the wires have been swapped between 1 and 2 or 3 and 4. It means the ECU is bad. Use jumper between the 1 and 2 for the ground circuit and retest. If it works, you can use as temporary measure.

Do not try to test the distributor sensor wires. Some comes from the ECU and is not 12 volt. They should be tested only with a DVOM.

im just list--after good inspection i unpluged wire to distrubitor and found inside crumbling apart-could bires be messing things up indide this 4 wire plug to my distrubitor

The wires could be bad but if they are affecting the engine, trouble codes should be triggerred.

So prior to this, it might be intermittently failing but after you have gone through them, it could cause more problem if the wires are shorted or broken.

cant do much testing till i replace connector.would you know where i could find a part like that.none in my area

Internal connectors for the distributor are not shown separately. External connectors comes as a harness set.

Your best bet would be the junk yard.