1990 chevy EFI 1500 305 cheynne

[Inze]

I have a cold start up hesitation problem,
I have recently given it a tune up, a new map sensor, a new o2 sensor, a new engine temp sensor, and checked to see if the throttle body was leaking (no it wasn't).
Any ideas??
When the truck finally warms up it runs fine, it gets worse in the colder weather.
The problem is not starting, it's when I press on the gas pedal after it's running that it hesitates and almost back fires in park and while moving until engine warm.

[danny350]

idle-air control motor? it's on the side of the throttle body and they sometimes stick.

[Inze]

I took your advice and changed it yesterday and still no luck

[Inze]

Still having a problem this truck and now has problems starting. It's an intermitent problem though sometimes it starts/ runs fine other times not so (on a start to start, min. to min. basis). The service engine light came on now and i get a code 44. Which is a lean mixture problem and tells me that I should replace the o2 sensor, check the fuel pressure, wiring, and throttle body gasket (I recently torqued it down tighter no difference!). I changed the o2 sensor last summer and I also replaced the map, sensor, plugs, gas filter, engine temp sensor, idle air cntrl motor, air filter, and I yesterday I cleaned the fuel injectors, and now it's not reliable and won't start all of the time anyone know what the most common problem would be. How do I chk the fuel pressure? The injectors have fuel comming out of them and the truck dosent turn over so im thinking it's not a fuel pump prob??????

[hyjack]

Originally Posted by Inze

Still having a problem this truck and now has problems starting. It's an intermitent problem though sometimes it starts/ runs fine other times not so (on a start to start, min. to min. basis). The service engine light came on now and i get a code 44. Which is a lean mixture problem and tells me that I should replace the o2 sensor, check the fuel pressure, wiring, and throttle body gasket (I recently torqued it down tighter no difference!). I changed the o2 sensor last summer and I also replaced the map, sensor, plugs, gas filter, engine temp sensor, idle air cntrl motor, air filter, and I yesterday I cleaned the fuel injectors, and now it's not reliable and won't start all of the time anyone know what the most common problem would be. How do I chk the fuel pressure? The injectors have fuel comming out of them and the truck dosent turn over so im thinking it's not a fuel pump prob??????

I have the same problem with same truck. Did you ever find out the problem. Thanks,

[Inze]

Originally Posted by hyjack

I have the same problem with same truck. Did you ever find out the problem. Thanks,

Yes It was the throttle position sensor!! After all that it finally fixed it with now problems at all. It's an easy fix the thing bolts right on the top of the throttle body. Let me know how you make out..