van runs terribly when cold, hunts for idle and will die, backfires through air filter, big hesitate and lack of power. If I pump the gas it will pickup and run.

Runs just fine when warmed up, but is getting bad mileage (like 10mpg) and doesn't like to start when hot.


I have replaced: plugs,wires,dist cap and rotor, fuel filter (was clogged), coolant sensor and TPS!

I don't know what to check next, suggestions please?

TIA!

 

I would check the fuel system from end to end if it was able to plug up a filter. I'd check the catalytic converter too.
Steve

 

Only 2 things cause that to happen. The first is a very lean condition due to low fuel delivery, a large vacuum leak, or a bad choke setting on a carb. The second is if the timing chain is stretched or worn enough so the spark plugs are firing before the valves have fully closed.

 

Thanks all. I will get the fuel system / pressure checked again. There was damage to the fuel tank some time ago.

however, why would it run fine and have power when warm?

 

Just to close this out for search / historical purposes, it turned out to the be the IAT (intake air sensor). Also need to reset the ECU (device or just unplug battery) to reset the Block Learn tables and bring the mixtures back in line.

thanks for help guys.

 

Is there a way to test these sensors without having to replace them one by one??

 

Yes, in most cases there are just a couple of pins you need to put a meter on and the service manuals show the acceptable ranges.