454 TBI, yes/no good/bad idea?

[Boom Sounds]

My 1991 250 classic has a stock TBI with 4l80E. Happy to share any info if you need any, just PM me. allbest Nick

[PeterH-350LE]

Originally Posted by bkahler

Peter, that seems odd that you would have a fuel smell. I was kinda thinking the odds of that would be less for TBI.

Is it possible you one or more leaky injectors? I know leaky diesel injectors smell but the odor is usually from the exhaust not the engine itself.

Fuel should only be allowed into the top of the manifold when an injector is energized. And they are only energized when the engine is running.

I should have clarified that the fuel smell is only for some time after I shut the engine off and not doing operation.
I will do a visual check if I have leaky injectors.

[PeterH-350LE]

no leaky injectors, but I found these little piston with 2 rubber rings that are leaking. Where in the world can I find 4 of those rubber seals that will fit. I do have a package with an assortment of seals and found some that fit the ID, but the OD is too big. Any suggestion where I could try to find some?

[rmkrum]

Probably need carb rebuild kit?


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[bkahler]

If the throttle bodies aren't GM then you'll have to check with the manufacturer.

If they are GM then you can try looking them up on a site like GM Parts Direct.

If you buy them from a non-automotive place then make sure they are rated for modern fuels.

[PeterH-350LE]

I may have found the replacements at the Holley site and ordered some. Until they arrive, I made the ones I had "fit" with a drill and some sandpaper.
No more leaks. Thanks for questioning my fuel smell issue. Its a lot less now, but this Holley TBI injects right on top of the butterfly flaps, so one can expect some odor after shutting the engine down.

[bkahler]

Necessity is the mother of invention!

Any idea what those pistons do?

[bkahler]

Originally Posted by Boom Sounds

My 1991 250 classic has a stock TBI with 4l80E. Happy to share any info if you need any, just PM me. allbest Nick

Nick, pictures of the engine and transmission from various angles top and bottom would be very helpful

[PeterH-350LE]

Originally Posted by bkahler

Necessity is the mother of invention!

Any idea what those pistons do?

I called them pistons for a lack of a better word. They are fuel transfer tube connectors and are stationary.

[PeterH-350LE]

Damn Brad, you are a bad influence as Steve suggested. Now after I fixed the leak at the throttle body per your suggestion, I don't get any more gasoline fumes to keep me going. What you gonna do about that???

[bkahler]

Originally Posted by PeterH-Airstreamer

Damn Brad, you are a bad influence as Steve suggested. Now after I fixed the leak at the throttle body per your suggestion, I don't get any more gasoline fumes to keep me going. What you gonna do about that???

I'm not a bad influence, I'm just an enabler of course that could be said for just about everyone on Airforums

I'm sure you'll be able to find some other source of fumes to keep you going as a leak is bound to show up somewhere when you least expect it...

[chriscraw]

I've been trying to find a place top post this as a "warning to 454 TBI owners" so here goes!
(disclaimer..I'm not a mechanic but won't admit it and am in denial!)
My 350LE is equipped with the 454 TBI which, given the 16.000lb weight, the significantly under-powered 454 and full thickness Corian counter tops, had managed to pull the Classic up the odd hill in first gear while slip-streaming the semi in front!

Recently, after staring the engine (fine), I stopped at the end of my driveway to close the gate. and turned-off the engine. Some 10 minutes later, after steadying my nerves (for those who have not driven one of these 35 foot long behemoths on the road, this is a necessary yoga-like move) and clambering over the "dog-house" into the driver's seat etc., the engine turned -over but would not fire. So this is the sequence of "trouble-shooting" which I hope will save other AS owners with a similar symptom considerable time and a reduced alcohol consumption!
1. was getting fuel (too much it seems)
2. was getting spark but sort of weak
3. changed-out distributor cap, rotor, coil and ignition control module..no improvement
4. replaced MAP sensor, oxygen sensor...no improvement but sort of started..rough idle
5. replaced fuel regulator and temperature sensor...ran smoothly when cold but as warmed, ran rough.
6. as I had already replaced the EGR valve and cracked base some time ago, did not think that this was the problem until I inadvertently fell on the EGR vacuum hose which came to pieces in my hand as I "saved" myself from straddling the engine bay!
7. replaced the EGR vacuum hose and problem solved!
I had borrowed a vintage OB-1 reader but could not get a connection or code which may have saved me the 1000 hours eliminating the fault!
Now, if only I could be as successful with the other "to do list" items!

[Keyair]

Good info Chris.
I too have never been able to get a "OBD1" code reader to work on my '87 suburban, and ended up always using a paperclip in the ALDI connector to flash the CEL.
You just put a paperclip or piece of wire in the two pins on the top right side of the 12 pin connector under the dash and it flashes the code... say, 2 flashes, the a 2 sec delay, then 4 flashes will be Code 24, etc.

[chriscraw]

Snr. Keyair..good to know next time I experience a "hack attack" on the 350. Assuming I can get a code, where is the information that might allow me to decipher the code?
chris

[Keyair]

I made a spelling error... its called the ALDL, or Assembly Line Data Link.

Tricky to answer, but here should give you a start...
http://www.troublecodes.net/gm/

[bkahler]

Any clues as to why the OBD-1 readers don't seem to be connecting to the ECM/PCMs properly?

I know the PCM I'll be using is considerably faster than the earlier versions so maybe that has something to do with it. Of course I'm a long ways from being able to test that theory!

Brad

[bkahler]

Steve, just an update on TBI vs carburetor heights.

The 2" throttle body with the Spectre carb hat that I am planning on sits 5-9/16" tall from the where it sits on the Edlebrock Performer intake manifold to the top of the carb hat. The wing nut is 1/4" tall so Overall height of the TBI unit is 5-13/16". However I still need to account for the TB adapter plate which will I will likely make out of 3/4" aluminum plate so the overall height will actually be 6-9/16" to the top of the carb hat wing nut.

The Edelbrock 1406 carburetor and carb hat sits 7-1/4" tall from the surface of the manifold.

Keep in mind the TBI numbers don't include that cooling donut which I don't plan on using. This means the TBI will sit 11/16" lower than the carburetor I was planning on using.

One of point of interest. It appears the 1994 stock TBI intake manifold has a carburetor pad height that is almost identical to the pad height of the Edelbrock intake so you likely won't gain any room by switching to the OEM TBI intake manifold. I know you're planning using the OEM manifold more for emissions that anything else but don't count on gaining any head room when doing so.

I suppose that's my good news for the day

[J. Morgan]

Paint the Edelbrock engine color and I bet the emission inspector will never notice it...


Talis gentium ceciderunt.

[Keyair]

The Edelbrock manifold actually has a CARB EO number, so it is smog legal!

[Boom Sounds]

Brad - the van is coming out of winter storage this weekend so let me know if you still need any info/pictures on the TBI set up.

Nick


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