ok so I bought this 97 Chev 2wd last week. Truck has the 4.3 and when I got it the truck had no spark.


The kid bought it and drive it about 10 miles after getting the MVI done and it stopped and didn't want to start.


He changed before the MVI, fuel pump, lines/filter and after the MVI and no spark he changed the coils, wires, plugs, cap and gave up.


So I bought the truck for what he was asking without beating him down (feeling bad) and my mechanic went to work on it.


Now please understand I do the work on my Suzuki 4x4 but I am not current on most other models and some terms I use might not be accurate.


He took parts off of a working truck and changed the crank senser, coil(again), distributor and I know there was a few other things. When he swapped in the new ECU he got spark and it fired right up.


Now it gets weird. So it fires right up but sounds totally offal...we can tell it's either not firing on all 6 or the firing order is wrong. It will kind of idle and if you gently push on the throttle it will go up in rpms...at a certain point it kind of sounds like it evens out but it's quick to sound bad again.


We did change the fuel to rules that part out and it has zero power to move around. We checked and double checked the firing order and it's where it's supposed to be.


It also backfires pretty intensely at times. I pulled the ECU and trying to find someone to let me put it in their trucks to see if it works.


Can we confirm that the ECU for the 4.3 is the same as the 305? the junkyard tells us that it is and we know the serial numbers are the same.


Ideas we got:


1- bad ECU


2- timing chain jumped a tooth or two


3-...we are out of ideas.


Please help and shoot me off some ideas and thanks

 

This is my truck, it looks pretty good and it was an old man that had it since it was new. Just need help to get it going good.

 

I'm no vortec expert but I don't see how a V6 and V8 could use the same computer since timing is contolled by the computer.

 

well like Burnedge puts it....how can a V6 ECU run a V8 ECU the same way.


When we went into the only junk yard that had one in stock we were dealing with a VERY special person and I kept asking him "how can a V6 and V8 have the same computer" and he kept telling me with this strong redneck tone that it did....yeah right.


So I stole the ECU off the neighbours truck and went down and my truck purrs, going to drive it to the local chev dealer and they will flash the V8 ECU to make it run.


I have always run carbs and this is why....