CPI injector spider
 

Can anyone tell me how the spider operates on the 4.3l cpi motors? do they have an idle circuit and a power circuit like a carburator or does it just pulse fuel like a tbi unit. My 94 s10 idles fine and has 62 lbs fuel pressure at idle and only drops to 48 at wot. all sensors check out as good, new fuel filter and air filter, Replaced plugs wires distributor car and rotor. Truck has new exhaust from the cross pipe back. it just falls flat on its face when i hit the gas going down the road. in overdrive it cuts out about 2500 rpms.
any help would be greatly appreciated.
Thanks

RE: CPI injector spider
 

It falls on its face because the fuel pressure at WOT is supposed to go up, not down. So you have fuel starvation problem going on. I see you already tried a fuel filter so it probably is a pump. These injectors vary fuel delivery based on pulse width, more fuel- on longer, less fuel - on shorter. These systems use the ECM with inputs from the MAP, O2, TPS, and other sensors to base its fuel delivery pulse width.

RE: CPI injector spider
 

I thought that as the rpms incress that your fuel pressure should drop a bit, if wot the injector is pulsing longer then there should be a drop. simalar to having your finger over the end of a garden hose, with it covered pressure is high move finger water flows and pressure drops. Does anyone know how the pulsing of the spider distrubutes the fuel to the 6 differnt lines. Does this part of the injector ever go bad. Soposedly just before i got this truck the fuel pump was replaced, i know it is running because it is so loud that i have to turn the radio up to cover the humming. i have never heard of a fuel pump going bad by gradualy loosing pressure every one i have replaced just flat out quit. is this normall? Thanks for any help, Tim

RE: CPI injector spider
 

At an idle the pressure rugulator allows less fuel pressure, when you take away the vacuum at wot, the regulator increases fuel pressure. All of the lines get fuel every time the injector pulses, the injector sits in the middle of the 6 lines and feeds them all, that is why this system is not used on the 96 and newer, because the EPA stated that each injector must be controlled individually. And your fuel pump should not be that loud. If when your truck is running and you can hear it to where you need to crank the tunes, that is most likely your problem.