'02 4.3 Wont Start/Intake Backfire


obryan
02-28-2008, 05:55 PM
Hi! I have an 2002 S10 with a 4.3 Vortech motor. My truck has ran great and it sat for 3 weeks. Now it wont start, it diesels when letting off ignition and backfires in intake. Also, fuel pressure is 60psi. I thought GM was american. considering a Ford now.

old_master
02-28-2008, 06:42 PM
Induction, (backfire through the intake), is usually caused by a fault in the secondary ignition system, or ignition timing being advanced too far. More than likely, you'll find a problem with the distributor cap, rotor, or spark plug wires.

obryan
02-28-2008, 07:21 PM
thanks, i'll check that. but what about the low fuel pressure??? it needs 80-90psi and im only getting 60psi?? thanks for help

old_master
02-28-2008, 07:30 PM
Fuel pressure spec is 60 to 66psi, pump running, engine off. Pressure must remain above 55 psi for 3 to 5 minutes after the pump shuts off.

obryan
02-28-2008, 08:35 PM
really?? guy at autoparts store looked it up and it said 80. so if im running right pressure, i should look at distributer cap?? I havent adjusted anything

old_master
02-28-2008, 08:43 PM
Better find a new auto parts strore, they're not helping you at all ;)

The fuel pressure regulator will regulate pressure anywhere between 60 and 66psi, depending on internal spring pressure, (not adjustable). Get a good distributor cap and rotor, AC Delco preferrably. Stay away from the discount "chain" type auto parts stores... unless you're selling the vehicle ;)

obryan
02-28-2008, 08:49 PM
ok, will do, let u know whats up

83cutlass
02-28-2008, 08:58 PM
I bet its crossfiring in the dist cap. I definitely second the get a good dist cap comment. My friend bought a cheap one that lasted about 6 months/9,000 miles B4 it started to misfire and crossfire. This time we used an ACDelco one.

obryan
03-03-2008, 07:30 PM
Found Problem!! took cap and rotor off and they were all rusted and oxidized!
filed and cleaned points and rotor and it fired up back to life!! know ill need to change cap and rotor eventually though! thanks for everyones inputs. ur great!!!

old_master
03-03-2008, 07:49 PM
Found Problem!! took cap and rotor off and they were all rusted and oxidized!
filed and cleaned points and rotor and it fired up back to life!! know ill need to change cap and rotor eventually though! thanks for everyones inputs. ur great!!!

Glad you got her going! When you do replace the cap and rotor, make sure you use a good brand, (AC Delco), and use silicone dielectric grease on the terminals in the cap and on the rotor tip. When the engine is running, the silicone dielectric grease will crystalize and is probably what you saw on your existing cap.

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