5.7 won’t start-blows air back through TB

[SuperTramp]

i could benefit from your experience, please. ‘98 k2500 4wd, 5.7. (All original) Engine won’t turnover. Upon returning key to ACCESSORY, engine coughs air back through carb. ( I can email/text recording if you’re interested) Fuel pump pressure at 60 lbs, complete tuneup 1 year ago (plugs, wires, rotor, cap- will replace fuel filter soon) anyone have any suggestions?

 

[94burbk1500]

Define "won't turnover" does it crank at all?

 

[SuperTramp]

Define "won't turnover" does it crank at all?

When it wants to; it sat for a week- then wouldn’t start. I worked several hrs trying to diagnose. I loosened bolts on one pipe where exhaust meets the down tube to see if it might be a clogged cat. No starting. Next day it started right up and I drive it for about one hour over two days, making several stops and starts. Following weekend, it wouldn’t start.

 

[SuperTramp]

About a year ago, one of the cats was making this sound (listen to attached video, please). But it stopped making noise about 2-3 weeks later. It’s a single exhaust and still is putting pressure out tail pipe. I do not know if pressure has decreased.

You must be registered for see images attach

 

[94burbk1500]

There's no video attached. A bad cat won't prevent the engine from cranking. Let me be clear that by cranking I mean is the starter turning the flywheel making the rotating assembly spin. If it is not cranking, or is intermittent, you need to inspect the starter, it's cable to the battery, the battery, and the grounds.

 

[SuperTramp]

There's no video attached. A bad cat won't prevent the engine from cranking. Let me be clear that by cranking I mean is the starter turning the flywheel making the rotating assembly spin. If it is not cranking, or is intermittent, you need to inspect the starter, it's cable to the battery, the battery, and the grounds.

Thanks for clarifying cat concerns. Yes, to your check list beginning with starter turning. I’m also getting spark.

 

[94burbk1500]

Ok, so just to make sure we are on the same page, you have fuel pressure from the pump, you've checked spark, the starter does turn the engine over, it just doesn't fire?

 

[SuperTramp]

Correct for each you are asking about

 

[94burbk1500]

Have you tried giving it some starter fluid? I'm just trying to rule out the basics before anything drastic.

 

[SuperTramp]

I understand. Yes, I’ve sprayed starter fluid in carb throat. I have a audio file I’d like for you to hear but I cannot figure out how to upload it. I can probably email it to you.​