I am intermitanly getting this fuel leak out the bottom-ish of the TBI. Can someone please give me some insight...ask questions so that i can head this off and get everything right. It's not out of the throttle linkage. The TBI was rebuilt and it developed this leak. Injectors have nice cone shapped sprays, while the passenger side one drip-leaks slightly (replacing that soon). Having an issue with no spark coming from the distributor...but it shouldn't have that issue of fuel all over the intake. If someone can please tell me in 20 years i'm not the only one with this issue and someone can tell me what to do to cure this. Thanks!!!!

 

First pic is driver side TBI...2nd pic is passenger side TBI to show it's coming from both sides for whatever reason. Third picture is front driver side of the TBI. 1988 Pontiac Firebird with a 5.0L TBI.

 

What's that disconnected line on the front?

 

Have you changed the throttle Body gasket? Now might be a good time. And I am not 100% sure if that line that is disconnected is a Vacuum line? Might be but hard to tell.

 

It is the vaccuum line that carries to the diaphram (i believe) in the intake to open and close it (connects the intake to the exhaust to heat the car up faster when engine is cold). That i had covered up when attemtping to start, when the gas just kinda like cascaded down the side slowly...it didn't gush out. And it seems to be worst when i stop trying to crank the motor. So i knew that vaccuum line was disconnected.

I rebuilt the throttle body...which included the two O gaskets for the intake neck and the throttle body to intake gaskets. All gaskets and everything above the intake was replaced. Thank you guys for your prompt responces...anything else you can think of???

 

Just out of curiousity, The picture on the far right. You have a green GM hose clamp that isn't connected. What is that rubber line.. It looks like a fuel line? I would check all your lines steel and rubber to check for pressure leaks.

 

There are several good possibilities.

First look for hair line fracture near inlet-outlet fuel taps into fuel injector pod body. Get a small mirror on a flex stick and take a look at the bottom of the inlet-outlet fuel adaptors into pod. Let engine idle while observing the back side of TBI near fuel line taps.
Second possibility is a leaky TB to manifold gasket. This is common in high mileage motors. Over torqueing TB bolts may warp and crack TB body.
Thirdly - cracked TB around throttle shaft which may explain driver side leak.

//RF

 

your best bet would be to take the throttle body off, or atleast the throttle body pod that sits on the injectors (the 8 torx screws) and check your gasket the goes from the fuel pressure regulator to the throttle body, its the little gasket the looks like an 8. and also check to make sure that the injector that is leaking, that the o ring on the bottom of the injector is seated properly and the large o ring on top of the injector is seated properly.

 

Another thought you might want to try. Do a really good job cleaning up the TB and the intake and anything around it. Then dry it really good. Right now you are trying to find a gas drop in the middle of a puddle of gas. If you cleaned and dryed everything real good, It would be easier to help locate the source of this leak(s).

 

when i rebuilt the throttle body...i cleaned the 140K worth of gunk and nasty **** out of it. It was as spotless as a none-polished aluminum throttle body should be, and then dried over night. All the gaskets are new. I have as of the other day taken it apart and checked all gaskets because i wanted to try and solve the issue myself. Worked for all of a day and now the issue is back. The figure 8 gasket is lined up as it should be. The gasket between the pod and the throttle body that is pinched with the 8 torx screws is in there just as it should be. As mentioned, all gaskets and rings above intake were replaced with new. When taking the throttle body apart the 2nd time to see if i installed something improperly, i double and triple checked the o-rings for the injectors. They are all seated as instructed to be installed. I believe that it is dripping from a bad injector (if that is not possible please correct me). Everything on this car was still all original delco parts. I have a feeling that there was minimal maintenance done to this car before i bought it.

In lighter news...just did a plug/wire/cap/rotor job and found all 8 plugs engorged in oil (99% positive why she won't start). Guess i should start doing research on a 350 swap. Thanks for the input guys...i will recheck the o-rings one more time...but i do believe i have them seated correctly. Keep up the ideas!!

 

IBM...that hose leads to the driver side head...i believe it's call the positive crankcase thingy, lol. That i know about, i moved it back after the picture was taken.

Are these throttle bodies known for cracking?? Just curious because the thought passed through my head, and i didn't understand how the crack would have developed just sitting atop the motor. Then again that would explain why it leaks being i cleaned it so well. Will check further...

 

I just rebuilt my TBI. Here's what I would be thinking in your situation.

• The nylon seals on the fuel inlet and return fittings that screw into the injector pod through the back of the TBI. They look like very thin flat washers made of almost clear nylon and basically snap on the end of the fitting before it's screwed into the base of the injector pod. These could easily be forgotten during assembly. I believe replacements came in the TBI rebuild kit.
• The o-rings on the ends of fuel inlet and return lines. Just as easily forgotten. They are different sizes and I don't think they came in the TBI rebuild kit. If they're missing, any auto parts store should have them.
• Injector pod gasket - the main gasket under the 8-9 small torx screws.
• The small two hole gasket underneath the top of the injector pod at the passenger rear side of the TBI. One of the torx screws goes through the smaller of the two holes. Excess fuel from the regulator passes through the other to the return line fitting/line.
• Regulator diaphram.

If the engine is running fine, I would suspect an external leak at the fuel lines/fittings. If the engine is running rough & rich, I would suspect an internal leak from the injector / regulator pod. The dripping of fuel from one of the injectors could also be one of the injector o-rings.

If any of this doesn't make sense, I have the exploded diagram from the rebuild kit that I can pictures of each of these items.

Let us know what you find.