Air leak?
 

I fixed the fuel pump. After I did that the wing nut on the throttle body broke somehow and the throttle body popped off when starting the motor. I found a nut to screw down the throttle body (9mm), but now I have this massive air leak. I don't know if it is an air intake issue or what. I am thinking an intake issue though. It sounds like it sucking in air and it's really loud. Can anybody guide me please?

Can you post pics of what you're talking about?

Yes, I will tomorrow if I get a chance. Me and a friend are working on a different vehicle. If I don't get it tomorrow, I'll get to it Monday. Thanks!

Year and engine would help.

On the 2nd gen Blazers, the air supply duct has a connection on the back side of it facing the firewall that connects to a long hose/tube that goes to the passenger side valve cover. Make sure that hasn't come off.

Also, double check that you have the duct correctly centered on the throttle body.

Okay, can you send me a pic of what you are talking about? Thanks Christine!

OK, so what I am talking about definitely falls under the category of "It is so easy to check, I might as well check this just in case it is the problem."

In the pictures below I've circled the places that occurred to me where a large vacuum leak could occur. But as I write this it occurred to me that there could be leaks all along the duct/snorkel. You might want to check the whole length of the the duct/snorkel too.


https://cimg9.ibsrv.net/gimg/blazerf...003c8e46b4.jpg
The way things should look.


https://cimg6.ibsrv.net/gimg/blazerf...0ff14b6c8d.jpg
Both locations with (exaggerated) gaps.

That's my exact engine! In the top circle, the wingnut is what broke and caused the issue in the first place. The throttle body blew completely off when it happened. I couldn't find another wing nut like that one, so I had to use a regular 9mm nut to tighten down the throttle body (I'm guessing that the lower circle is called the throttle body. Am I correct?) Anyway, I thought the throttle body might be leaking, but when I put my hand around the bottom part of it, I don't feel any suction going on. What do you think?

You can find them at about any salvage yard or pick n pull.

get the stub the nut goes on just in case.

So to be unambiguous, the throttle body is the metallic thing in the lower half of the lower circled area that has a butter-fly valve in it. The black part that supplies the air from the air filter is the duct (for the lack of a better word).

This duct must be sealed to the top of the throttle body as the sensors the engine computer uses to know how much air is being delivered the engine are between the throttle body and the air filter. If there is a place where extra air is coming into the engine, the engine can run rough or at least inefficiently.

Have you checked the length of the tube that connects to the back side of the duct and goes to the passenger side valve cover to be sure it has no leaks?

As for the wingnut, I would think you could get one at a U-Pull wrecking yard. They might even have them at a parts store or your local GM dealer (if you want to pay more money ;) ).

I am a bit concerned with how the duct was blown off in the first place. In carbureted engines when there is excess fuel delivered and the mechanical timing is off, the gas in the intake manifold can ignite and create a flame that goes up through the carburetor. I'm wondering if something like that happened to you. What prompted you to replace the fuel pump?

I was having a hard crank issue, It would crank easy for the first start of the day, but the rest of the day it would have a hard time cranking, so I replaced the fuel pump. That seems to have fixed that issue. But I won't really know until I am able to use the vehicle again. As of now, I am not using it until I get this air leak problem solved. As far as uploading some pictures, I think I'm going to have to get a camera because the upload is telling me the file type is not supported. So I'll get to it after I get a camera.