The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - Help before I go crazy. 99 suburban 5.7 vortec wont start.

rickpilgrim · 12-20-2011, 12:05 AM

bighaas79- I also don't have a problem with you, here's why I said what I did.
I realize you can use the Modus to do the pressure drop test, and you can set it lab scope mode and check the signal going to the assembly. That being said, our 98 K2500 was running extreemly rough when we got it, we did exactly what you said and it checked out perfect, just running a bit rich. Ended up pulling up the upper intake and found a few leaking lines and a little puddle of fuel in the intake, yet the data in the Modus said all ok and we followed the test instuctions that are in the modus.
Now I was thinking not everyone has this $6259.43 piece of equipment laying around, most have only a code reader with maybe a data display at best, like our ez5000 or ez6000. Thats why I posted that, as I don't know any other "low tech" way to do it.
Also, disconnect the battery for a week or two and the trouble codes go away and I have never seen the pcm set any trouble codes beyond the CPS if the engine won't run. Code reader no help here either
Like I said, try a cup of fuel down the intake first, that will at least point you in the right direction of where to look.

12-20-2011, 12:05 AM	#19
rickpilgrim Registered User Join Date: Apr 2011 Location: Wausau, WI Posts: 591	Re: Help before I go crazy. 99 suburban 5.7 vortec wont start. bighaas79- I also don't have a problem with you, here's why I said what I did. I realize you can use the Modus to do the pressure drop test, and you can set it lab scope mode and check the signal going to the assembly. That being said, our 98 K2500 was running extreemly rough when we got it, we did exactly what you said and it checked out perfect, just running a bit rich. Ended up pulling up the upper intake and found a few leaking lines and a little puddle of fuel in the intake, yet the data in the Modus said all ok and we followed the test instuctions that are in the modus. Now I was thinking not everyone has this $6259.43 piece of equipment laying around, most have only a code reader with maybe a data display at best, like our ez5000 or ez6000. Thats why I posted that, as I don't know any other "low tech" way to do it. Also, disconnect the battery for a week or two and the trouble codes go away and I have never seen the pcm set any trouble codes beyond the CPS if the engine won't run. Code reader no help here either Like I said, try a cup of fuel down the intake first, that will at least point you in the right direction of where to look.