ok here goes about 4 months ago i started to have problems with my car not starting so i did the usual checked the fuel pressure then i changed the fuel pump changed the ingnition module fuel filter fuel pump relay vats is bypassed under dash and in chip now it will crank but only if i hot wire the fuel pump and it running like 55 psi of fuel pressure and it dosent idle well like its getting to much gas i am very stumped any and all help will be very appreciated and welcome i miss driving my iroc and i know it cant be much wrong or is something im missing



1990 Iroc
5.7 L98
harris performance Chip
700r-4
3.23 rear
throttle body coolant bypass

ecklers vats bypass

 

Can you explain exactly what you mean by hot wiring the pump?

 

i have a switch run from the fuel pump to a constant 12v source and i flip the switch and the fuel pump comes on

 

so the pump is completely disconnected from the ecm?

 

the wire harness is still hooked up to the pump i just have a jumper connector on to the 12v wire and have it hooked to the toggle switch the car will crank up and run but its not idling like it should and when u go to give it the gas it boggs down and feels like its flooding

 

Have you tried running it hot wired with the stock chip? If I were you, I would remove the hot wire completely, replace the stock chip, and then use a voltmeter to see if power is going to the pump throught the harness or not. If not, I would work my way back to the battery.

Have you pulled the plugs and examined them? Have you checked to see if your injectors are pulsing properly? Smell gas in the exhaust? Does fuel pressure change at all while idling or accelerating? Does it stay constant? Voltage across battery while running?

Once its up and running, then replace the stock chip with your aftermarket one if you really want it in. A lot of these chips simply trick the computer into dumping more fuel than necessary.

 

ok im not sure exactly how to check the injectors ive never done that before but with out the hot wire the pump dosent come on with either chip in but the tach does bounce around when idling the voltage stays pretty much the same as always it only smells rich when it first starts up and as it warms up

 

When you turn the car on, the pump does not come on. Have you checked to see if battery voltage is available and going through the relay? Have you checked to see if the relay is getting signal to click on? You might have a short to ground somewhere. Have you checked all fuses?