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Originally Posted by Glenn Peters
I hear that sticking poppets(injection) is common on the 4.3 Vortex. I also hear there is some sort of procedure to check this and free them up, I hear it's done while driving ????? Any one know about this by chance ?
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SOme GM engines (4.3,5.0,5.7) built between 95 and 02 have a Central Sequential Fuel Injection system equipped with ball on seat poppet valves...a poppet valve is a mechanical fuel injector.
These poppets are known to stick closed or open, caused by deposits from the fuels you use.
The sticking poppet can cause a misfire or no start condition..mostly cold or a general loss of power.
There is a GM technical bulletin #00-06-04-003B that addresses this issue...it includes a procedure for unsticking the poppets using high pressure nitrogen and a cleaning procedure...or.. if the poppets will not unstick there is an upgraded injector conversion kit that eleminates the poppets.
Personally I have had very good sucess with the unsticking procedure with probally less that 20% of vehicles needing the conversion.
The use of pour in injector cleaners or standard pressurized injection cleaning services will not unstick the poppets...The procedure outlined in the GM bulletin does work and from my experiance usually takes 8-10 attempts before a poppet will unstick ( you can cycle the injector /poppet assembly as many times as needed to unstick the poppet during the procedure)