I have the 1988 model 4ZE1 isuzu trooper, it would not start because the spark fron the ignition coil is low, I replace the coil and the same thing can any one advise me what to check. It is getting fuel on all the injectors, it have the optical distributor with 4 terminals.

Have you checked for trouble codes? There may be some stored in the computer without the light being on.
1988 Isuzu Truck Trooper II L4-2559cc 2.6L SOHC

Vehicle Level (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741) http://library.alldatapro.com/images/a_003366.gif Powertrain Management (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/34857029) http://library.alldatapro.com/images/a_003366.gif Computers and Control Systems (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/34857029/34857030) http://library.alldatapro.com/images/a_003366.gif Testing and Inspection (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/34857029/34857030/34857663) http://library.alldatapro.com/images/arrow1.gif Displaying & Reading Trouble Codes (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/34857029/34857030/34857663/100426641) http://library.alldatapro.com/images/arrow2.gifhttp://library.alldatapro.com/images/blnk_spc.gifDisplaying & Reading Trouble Codes "Check Engine" Light And Diagnostic Connectorhttp://library.alldatapro.com/alldata/LIB~C5110~R0~OB0~P3R0H~N/0/34870067/56620440/56620441/56620442/34853741/34857029/34857030/34857663/100426641/56674347/41951194

To access trouble codes, a test lead (white wire) and ground lead (black wire) are branched from the wiring harness under the center console near the ECM (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/34857029/34857030/101367125). With the ignition "ON" connect these two leads together. The "Check Engine" light will begin to flash code 12. Code 12 consists of one flash, a short pause, then two flashes. After a longer pause, code 12 will repeat two more times. This check indicates that the on-board diagnostic system is functioning. If no other codes are present, the cycle will repeat until the ignition is switched "OFF."

1988 Isuzu Truck Trooper II L4-2559cc 2.6L SOHC

Vehicle Level (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741) http://library.alldatapro.com/images/a_003366.gif Engine, Cooling and Exhaust (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974) http://library.alldatapro.com/images/a_003366.gif Engine (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743) http://library.alldatapro.com/images/a_003366.gif Ignition Timing (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58828689) http://library.alldatapro.com/images/arrow1.gif Specifications (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58828689/58800674) http://library.alldatapro.com/images/arrow2.gifhttp://library.alldatapro.com/images/blnk_spc.gifSpecificationsBase Ignition Timing 12°BTDC @ 900 rpm

1988 Isuzu Truck Trooper II L4-2559cc 2.6L SOHC

Vehicle Level (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741) http://library.alldatapro.com/images/a_003366.gif Engine, Cooling and Exhaust (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974) http://library.alldatapro.com/images/a_003366.gif Engine (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743) http://library.alldatapro.com/images/a_003366.gif Ignition Timing (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58828689) http://library.alldatapro.com/images/arrow1.gif Adjustments (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58828689/58059400) http://library.alldatapro.com/images/arrow2.gifhttp://library.alldatapro.com/images/blnk_spc.gifAdjustmentsAdjust ignition timing under the following conditions:



Engine at normal operating temperature.
Lights, A/C, and accessories turned off.
Engine idling at proper idle speed (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58948512), with throttle valve completely closed and idle switch "ON" (see IDLE SPEED under ADJUSTMENT PROCEDURES ).
Transmission in "Park" or "Neutral".Timing procedure:



Connect timing light.
Loosen distributor (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58948514) mounting bolt.
Adjust timing to specification: 12°BTDC @ 900 rpm.
Tighten distributor (http://library.alldatapro.com/alldata/LIB~C5110~R0~OD~N/0/34870067/56620440/56620441/56620442/34853741/100411974/34853743/58948514) mounting bolt.
Recheck timing, repeat adjustment if necessary.

I did that and i have all u describe what u think can cause it to give that low spark at the coil lead. with out a good spark the engin will not start, it get fuel the pressure is ok. do u think it can be the Control module in the distributer.

Yes it very well could be the module. should $20 or less, pretty easy to replace.