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Ironmike, ASE Master Tech, L1
Category: Car
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Experience:  30 years GM certified, Ford certified
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1986 isuzu pickup: idle..carb with new, does exactly the same

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1986 isuzu pickup,2.3 will not idle. replaced carb with new, does exactly the same. when i start it, it goes straight up at high idle, when i pat the throttle to set it the engine goes all the way down and quits then hard to start. where does 4 wire plug from carb go to get power? all fuses check out good.


With this system the ECM controls the carb and uses the 02 sensor and the coolant temp sensor to determine the fuel mixture.

You can start with getting codes, here is the procedure.

Connect white (test lead) and black (ground lead) wires that are branched from the fuel system control harness approximately 8 inches from ECM (These leads can usually be found near the cigarette lighter and will be wrapped in green tape if they have never been disturbed). After the leads are connected, turn the ignition switch "On". The ``Check Engine'' lamp will flash appropriate trouble codes. The codes are indicated by pulsing of the lamp. Two pulses followed by a short time lapse, then three pulses would indicate a code 23 and so on. If only one trouble code is stored, the code will repeat continuously until test leads are disconnected. If more than one trouble code is stored, each code will repeat three times, starting with the lowest, then proceed to the next code. After all codes have been shown, the pattern will repeat itself.
Trouble codes can be cleared by removing voltage to the ECM for 10 seconds. After a fault has been corrected, remove the ECM fuse or disconnect battery cables for 10 seconds.


Assuming there is no major vacuum leak , we can check sensors that the codes point to.


good luck

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Customer: replied 6 years ago.
for lack of a better choice im using a CHILTONS manual for this vehicle. according to the wiring diagram listed , it shows an ECM but says "california only". The only fuse box i've found is under the hood @ consisting of only 5 fuses, none are listed for the ecm. I' ve had the glove box, radio, and instrument cluster out looking for another fuse box and the ecm. please tell me what the ecm looks like and an approx location for it. The one on my Freightliner is about 8" by 10" and is bolted to the side of the engine, i should be so lucky on the pickup. Your help is much appreciated, this thing is driving me nuts .

sorry, they hide them sometimes. Behind I/P RH Side


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