ELD

Is there anyway to test the cold start injector or sensor? My fuel mileage drops from 16mpg in the summer down to 10mpg when it gets cold out.

Also have a problem now with the truck not wanting to start after it sets for 20 min. or so after driving it. When does start it runs like it is flooded out.



'93 V6 auto truck

4Hummer

Problem isn't going to be your Cold Start Injector or the CSI Temp Switch.

The Cold Start injector Only fires when the engine is A: Being turned over, and B: its Cold outside.

mt_goat

From the 93 truck FSM:
http://personal.utulsa.edu/~nathan-b...88coldstar.pdf

I've heard that they can get stuck on.

kpaxfaq

i had those exact symptoms and it was my cold start injector, got it replaced and it runs like new again

ELD

kpaxfaq,did your fuel mileage increase?

dcg9381

If you suspect the cold start injector doing something funky, simply pull the connector, drive for a tank of gas, check mileage.

mt_goat

If the injector was stuck open isn't it posssible it would still spray in fuel with the wire disconnected?

GT88Yota

You could try pulling it and cleaning it with some sort of solvent to dissolve the buildup. Sure is cheaper then replacing it.

Targetnut

You can remove the cold start injector and connect it to it's fuel pipe backwards. turn the key on and jump FP to +B in the diagnostic connector to run the fuel pump and see if the injector leaks. then you can energize the injector by jumping power and ground to it to check the spray pattern. Be careful to make the final connections to energize it away from the injector because spraying fuel and sparks can be a problem. then you can connect a test light across the harness connector and crank the engine from cold. the light should come on for a short duration which epends on the ambient temperature.

ELD

I did all the checks except for the test light to see how long the injector fires. Everything checked out within the ranges. I diconnected the wire going to the injector to see if it makes a difference and of course the temp. is now colder than it has been in awhile. Disconnecting the wire sure does make it difficult to get started up (duh!!) but seems to help with the shut it down for 20 min. and start it back up issue.

I guess I need to check the sensor after I run it and it has been shut off for awhile.

Anything else to check????