GMC Repair: 95 GEO PRISM - NO SPARK, crank shaft, crank sensor

Question
WE RECENTLY REPLACED THE ENGINE IN MY DAUGHTERS EARLY 1995 PRISIM. ALL WENT WELL UNTIL WE ATTEMPED TO START IT. ALTHOUGH THE ENGINE WILL CRANKAND AND IS PUMPING FUEL, WE ARE NOT GETTING ANY SPARK. USING A TEST LIGHT BETWEEN EACH PIN AND GROUND, WE HAVE CHECKED FOR POWER AT THE (2) CONNECTORS THAT ARE LOCATED AT THE DISTRIBUTOR AND HAVE FOUND THE FOLLOWING;
1) AT THE (2) PIN CONNECTOR, THERE IS CONSTANT POWER AVAILABLE WHEN THE KEY IS TURNED ON.
2) AT THE (6) PIN CONNECTOR, WHILE CRANKING OR WITH THE KEY JUST TURNED ON, THERE IS NEVER ANY POWER AT ANY OF THE PINS IN EITHER HALF OF THE CONNECTOR.

THE ENGINE WE INSTALLED CAME OUT OF A SCRAP YARD SO OUR FIRST MOVE WAS TO REMOVE THE DISTRIBUTOR THAT CAME WITH THE "NEW" ENGINE AND REPLACED IT WITH THE DISTRIBUTOR FROM THE ORIGINAL ENGINE. THE ORIGINAL ENGINE WAS RUNNING BEFORE IT WAS REMOVED.

WE HAVE BEEN TOLD THAT BECAUSE THE ENGINE WILL NOT START, THAT A DIAGNOSTIC WILL NOT HELP, CAN YOU?

THANKS
CARL

Answer
This is the EXACT REASON WHY I never recommend a junk yard as all the lectronic components that are on this junk yard engine are exposed to the weather and can be internally shorted and cause massive problems in the destruction of other related components that run on the same circuit as these faulty weather beaten electrical components.

You are going to have to do a lot of manual testing of electronic components in order to determine IF they are any good.

The FIRST thing I would check out and test is the CRANK SHAFT SENSOR. If this sensor has shorted out internally you may have destroyed the IGNITION MODULE and or the vehicles COMPUTER.

You MIGHT be lucky in that the crank sensor is the ONLY thing faulty.

The problems with JUNK YARD engines is that manufacturers make so many component changes and design changes every 6 months as well as every year to the electronics of the vehicles that unlees you get an engine that has the SAME PRODUCTION DATE as the one that you are replacing you ac run into component compatability problems.

EXAMPLE: They build an engine and install numerous electronic components and a computer into an EARLY YEAR 95 GEO PRISM and they have component rpoblems and they make numerous sensor changes, wiring changes and install a different ecm and this is where you get your LATE PRODUCTION 95 GEO PRISM.

So there are now compatability problems with the EARLY and LATE production components as the EARLY components will NOT work with the LATE components.

This is WHY when anyone asks about a JUNK YARD engine this is the problems that can and do occur.

The Thing that you should have done is to use ALL the electrical components from your engine and installed them onto the JUNK YARD engine and NOT use ANY of the electronic compnents from the JUNK YARD engine.

Even this is IFFY because they may have made let's say an EARLY model year crankshaft pulley that has 4 notches in it and the LATE model year pulley may have been re-designed with 5 notches in it and thus the sensors although LOOK identical are actually DIFFERENT internally.

This can also be the possibility with any other component.

Now that you have most likely used some of the junk yard electronic components you amy well have destroyed other components such as the computer due to compatability differences.


You will be VERY LUCKY if you get this setup to run correctly unlees you are well skilled in electronics anh have the necesary service manuals and electrical schematics to compare your old engines electronics and components against the JUNK YARD engines electronics and components.

Agreed, Back before electronics you could change engines very easily and sometimes install different size engines but with the introduction of computerized vehicles you just can't do it unless you hand check and verify each and every component.

You most definately have a long difficult task ahead of you.



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