Another Non Typical no start issue with my '97 Yukon

[stevo1975]

I won't complain a whole lot, I only paid $1850 for the truck, but here's my problem. Vehicle starts great, gets to operating temp, then if I stop at a gas station or grocery store for a few minutes, the truck will act like it's going to turn over but won't unless I step on the gas. Spark plugs could be the cause, but I feel this would cause hard starting consistently. I used to get code for catalytic converter, I'm wondering if it's plugged solid (came up as bank 1). Check engine light is no longer on. Funny, it idles fine once it turns over.

 

[TruckinAin4Sissies]

Check your fuel pressure, mine did that and it was the fuel pump.

Sent from my SM-G935V using Tapatalk

 

[east302]

If you have a scanner, see what the engine coolant temperature is reading. It shouldn't be some oddball low number. The sensor is by the thermostat, and can cause the issue that you describe.

Flooring it puts the computer in clear flood mode, turning off or reducing fuel flow from the injectors.


Sent from my iPhone using Tapatalk

 

[stevo1975]

Thanks for the replies guys. east302, I should have been more specific. All it takes is a little bit of the gas pedal and then she runs and idles fine. TruckinAin4Sissies I'll definitely have to get a gauge. Is there a shrader valve I can tap into?

 

[east302]

It's back toward the distributor.


Sent from my iPhone using Tapatalk

 

[stevo1975]

Thanks again. What psi am I supposed to get? I know this isn't mpi, so the pressure shouldn't be as high, in my mind anyway.

 

[east302]

Here's the pressure test procedure for a 1998 350...

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

Sent from my iPhone using Tapatalk

 

[stevo1975]

Thanks again for all the info east302. I'll be picking up the gauge on Friday.

 

[stevo1975]

So I did test fuel pressure - right at 62 psi. No bleed off. But as it got really warm here during the weekend, my truck was running worse, and I did catch a little black smoke coming from the exhaust, so I'm running rich. I'm thinking coolant temp sensor, seeing as how the truck runs really good when it's cold outside. The exhaust is so rich it's almost nauseating. It COULD be IAT, MAF, or even TPS, but I think I'll start with the obvious.

 

[east302]

The torque spec for the ECT sensor is 10 ft-lbs.

If you overtorque it, it can crack the lower manifold. Been there, done that.


Sent from my iPhone using Tapatalk