Mechanics

ENGINE MISSING

1990 Mazda b2600

Engine Performance problem
1990 Mazda b2600 4 cyl Four Wheel Drive Manual 164000 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?
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90mazda
March 19, 2010.



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.

KHLow2008
Mar 19, 2010.
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?

Tiny
90mazda
Mar 19, 2010.
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.

KHLow2008
Mar 20, 2010.
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?

Tiny
Jtc
Jul 14, 2010.
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.

KHLow2008
Jul 15, 2010.
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.

Tiny
Jtc
Jul 16, 2010.
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.

KHLow2008
Jul 17, 2010.
What is the cheaper way or how do I piggyback my injectors?

Tiny
Jtc
Jul 17, 2010.
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?

KHLow2008
Jul 18, 2010.
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

Tiny
Jtc
Jul 18, 2010.
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