1990 Mazda B2600 Engine missing

Tiny
90MAZDA
  • MEMBER
  • 1990 MAZDA B2600
  • 4 CYL
  • 4WD
  • MANUAL
  • 164,000 MILES
The engine is missing and I have a loss of power and gas is coming out of the exhaust. Thinking I have an ignition system problem I replaced the spark plugs, wires, coil, distributor cap, and rotor. I also checked the compression it seems to be good. There is a significant amount of gas coming out of the exhaust. Enough to leave a large puddle after 30 seconds of idling. Could the fuel injection be stuck wide open? Could the igniter be bad? Is there any way to check the igniter?
Friday, March 19th, 2010 AT 10:48 AM

54 Replies

Tiny
KHLOW2008
  • MECHANIC
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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.
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Friday, March 19th, 2010 AT 12:24 PM
Tiny
90MAZDA
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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?
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Friday, March 19th, 2010 AT 12:54 PM
Tiny
KHLOW2008
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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.
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Saturday, March 20th, 2010 AT 7:50 AM
Tiny
JTC
  • MEMBER
  • 30 POSTS
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?
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Wednesday, July 14th, 2010 AT 10:57 PM
Tiny
KHLOW2008
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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.
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Thursday, July 15th, 2010 AT 9:12 AM
Tiny
JTC
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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.
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Friday, July 16th, 2010 AT 9:41 PM
Tiny
KHLOW2008
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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.
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Saturday, July 17th, 2010 AT 1:36 PM
Tiny
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What is the cheaper way or how do I piggyback my injectors?
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Saturday, July 17th, 2010 AT 7:47 PM
Tiny
KHLOW2008
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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?
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Sunday, July 18th, 2010 AT 3:17 AM
Tiny
JTC
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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
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Sunday, July 18th, 2010 AT 8:59 AM
Tiny
JTC
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Test for continuity explain how to make tkis test will find a test light
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Sunday, July 18th, 2010 AT 9:45 AM
Tiny
JTC
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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?
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Sunday, July 18th, 2010 AT 12:34 PM
Tiny
JTC
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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
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Sunday, July 18th, 2010 AT 12:40 PM
Tiny
KHLOW2008
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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.
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Sunday, July 18th, 2010 AT 2:33 PM
Tiny
JTC
  • MEMBER
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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
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Sunday, July 18th, 2010 AT 2:48 PM
Tiny
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Yes, that is correct.
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Sunday, July 18th, 2010 AT 2:55 PM
Tiny
JTC
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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 wrongtester= 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.
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Sunday, July 18th, 2010 AT 3:13 PM
Tiny
KHLOW2008
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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?
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Sunday, July 18th, 2010 AT 3:29 PM
Tiny
JTC
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This is what I did- disconect cpu inside truck -- unpluged 1 and 4 injectors----connected tester to positive on battery---switch is turned offconnected 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
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Sunday, July 18th, 2010 AT 3:45 PM
Tiny
KHLOW2008
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Remove from 1st and try with 4th injectr. What is the result?
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Sunday, July 18th, 2010 AT 4:07 PM

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