ChevyG30

Please help!
My G30 Chevy, 350 small block van stalls out after about a minute of idle. Starts ok. Also I do experience some engine hesitation on hills, or in the 5-15 mph range. Once I get past 20 mph, all is ok.

In the past 5k miles, I've replaced:
fuel pump, filter
all plugs / wires
ignition coil
dist cap / rotor
PCV valve

In trying to debug this stall, I've:
cleaned throttle body (replaced bottom gasket)
replaced TPS
cleaned IAC valve (and measured ohms = all good)
replaced fuel filter again

It seems that the engine is running lean - so either too much air or not enough fuel. Any ideas for next steps? I'd like to figure out as much as I can before taking it into a shop and spending $$.

Irish_alley

what year? i know i keep saying it but check you battery connections make sure theyre clean and tight and you have good grounds

ChevyG30

1987 TBI 5.7L
how do I check good grounds?
I did measure voltage on the TPS and I do see the 5V supply rail ok. I used a ground on the engine body.

canucklehead

Secondary injector not working or not working well?
It supplies the extra fuel at idle when cold, and the extra squirt when you accelerate. Thus the hesitation.
Have you check ed them, or done any fuel system cleaning?

Irish_alley

take your grounds off and clean them.

ChevyG30

Thanks for the help. Let me look up more info / location on the secondary injector.
I did add a fuel additive the other day - but I was still at 3/4 full tank of gas.

Irish_alley

not that i think i know a lot and could be 100% wrong, but i kind of find it hard to have secondary injectors when theres only two and each one goes to its respected bank. extra fuel is done all by those two injectors and they should be spraying in a cone. no drips or jets. if you unplug the CTS it would mimic aa really cold start up and you will see the injectors dumping more fuel

ChevyG30

Thanks for your help Irish_alley!
Let me try to unplug the CTS and give it a start. (just to confirm - the coolant temp sensor, right?)
Also, the fuel injectors look to be working ok - a good spray (that I can see). No drips or direct streams that I can determine. But, I'm fairly new at looking at the fuel injectors.
What about other sensors like the MAP or an O2 sensor in the exhaust system?

Irish_alley

yes coolant temp sensor on the intake next to the thermostat.
wrote this up a few years ago and it goes through what each sensor can do and how to test them
Troubleshooting sensors and how to test