Hey guys needing some advice I’m working on 1989 Chevy s10 blazer 4.3L 4x4. I lost reverse so it sat for a couple years then I got back to it so I pulled out the 700r4 and rebuilt it in my kitchen… wife loves me… figured since I had t-case out take a look in side chain was sloppy so minimal rebuild kit.. slapped it back together. Dropped the gas tank good and clean replaced the in-line filter. New battery plugs wires cap rotor. …. Hit the key crank crank crank sputter checked vacuum lines … old cracked time for new new ones and t and the t valve crank crank crank same results so tbi off and deep cleaning new Iac valve new map and the module under the cap … oops accidentally left the vacuum line off the map sensor and it fired right up … ran for bout 20-30 seconds then it like key off I can see fuel pulsating and I have fire but it won’t start with map vac hooked up … I have searched and talked to other mechanics and can’t seem to figure it out … any and all advise tips tricks help

 

So when you crank but no start you have 1" of strong blue spark with a consistent cadence at the plugs but poor fuel pressure? What is the fuel pressure doing?

George

 

Yes I have spark and I don’t know psi on the line but I can see the fuel pulsation on the tbi

 

"I lost reverse so it sat for a couple years then I got back to it so I pulled out the 700r4 and rebuilt it in my kitchen… wife loves me…"

Our Hero!!!!

When youve changed all the mechanical parts and it still dont run, suspect ignition. What George said, blue- white spark is a MUST.

I had to put a bypass relay from ignition power to distributor due to bad wiring conections starving the ignition for power on my 1995.. Very important to put at least a DC voltmeter on the power at the distributor and timing light on the plug wires, an automotive oscilliscope is better but few have them.