I just got a 4.3L 262 Z motor from a 95 chevy truck. The problem is the motor diesels down when you kill it and smells like fuel for the first ten minutes. Also the guy that had the truck said it got about 6 mpg on the highway. Timing is set at 0 and wonder what else the problem could be. Motor was free!

 

Maybe leaky injecters or grounded injecters.

 

What does it have on it (CPI? TBI?). I dont remember what the code was for each of the induction systems. If its got CPI or whatever they called it then theres your problem right there... Leaking fuel and carbon deposits will enable it to diesel after you shut it down.

 

It has a throttle body injection. Bad sensor maybe

 

Is this 3rd gen related? If not this will get locked. Just a hint.

Anywhoo, dieseling can be assocaited with the following,

Idle speed to high
Improper timing
Exsessive engine temp due to malfuncioning t-stat, clogged radiator or faulty water pump

 

Once the engine is shut down there shouldnt be any fuel available for the motor to diesel on other then what remains in the manifold after shutdown. Turn the key to the 'ON' position several times after shutting off each time for more then 5 secs. to prime the fuel system and check around the injector pod to see if its leaking fuel from anywhere.

EDIT: If all that looks good then check the above.

 

new water pump, and just flushed radiator. Could be t-stat though. And yes this is 3rd gen related. Have blue cam. with a 305 in it now only i use it as a pizza delivery car. gas mileage sucks.

 

So is this problem with the 305 or the 4.3? If it is the 4.3 than it is not 3rd gen related.

 

come on now dont dissapoint mr..shifty..his goal for the day is 1 lock b4 lunch..

ps..i check your timing agin and what grade fuel are you using?

 

I guess if its a 4.3 in a thirdgen then its at least quasi-thirgen related. The fact that you smell fuel is one clue. Have you checked for fuel leaks yet? If it only diesels for a second or so then it may not be related but if it carries on for a bit then there has to be something thats supplying it fuel. Unlike a carb, once the key is turned to the off position, there shouldnt be any more fuel available for the engine to run off of.