I tried to start the Ford explorer last nite again and it back fierd by the vacuum pipe on top of the engin and smoke came out there and by the air filter too.
Recall ID # 10622 - FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS Full Details Recall Date MAR 19, 1998 Component FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS Model Affected Explorer Potential Units Affected 320000 Read more: http://www.motortrend.com/cars/1997/ford/explorer/recalls/#ixzz2NPkY6DoW
Recall ID # 10622 - FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS Hide Details Recall Date: MAR 19, 1998 Model Affected: 1997 Ford Explorer Summary: VEHICLE DESCRIPTION: MULTI-PURPOSE PASSENGER VEHICLES EQUIPPED WITH 4.0L SINGLE OVERHEAD CAM ENGINES. THE ENGINE FUEL LINES CAN BE DAMAGED IF THE VEHICLE IS JUMP STARTED AND THE GROUND CABLE IS ATTACHED TO THE FUEL LINE BRACKET THAT IS LOCATED NEAR THE BATTERY. SINCE THE BRACKET IS NOT GROUNDED, THE STAINLESS STEEL FUEL LINE BRAID COULD ACT AS A GROUND POTENTIALLY OVERHEATING THE PTFE INNER LINER OF THE FUEL LINE RESULTING IN DAMAGE TO THE FUEL LINE. Read more: http://www.motortrend.com/cars/1997/ford/explorer/recalls/#ixzz2NPk9LrbJ
Now that probably has nothing to do with it backfiring, it's just FYI, something I found while researching. But when you say "vacuum pipe on top of engine" do you mean the PCV? If so it is backfiring, or somehow explosively forcing combustion chamber compression in to the crankcase...not good...could be a broken piston or ring(s), it would have to blow by the cylinder in to crankcase to do that. But what you describe ...the other end of that hose, from PCV valve goes to air filter. So it makes sense. Do a compression test on all cylinders.
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