1994 GM P-30 TBI ?s

[udidwht]

I own a 94 Southwind Storm motorhome (454 TBI w/4L80E) and thus far she has been very reliable. I purchased it back in Sept 2014 with ~45K on the odometer. I'm now at ~74K. I'm going to pull and rebuild the TBI here soon and was wondering if there is anything I should do while I have it off? This will just be a basic rebuild (gaskets, o-rings). I purchased a Delco rebuild kit for it Rochester 220 I believe. It has never been rebuilt and currently runs great. Once at operating temp it idles at 800rpm steady in Park. I also replaced the large AC condenser w/integral oil cooler this past Sept (leaking oil cooler) and clean out the radiator tube fins hwile the cooler was out of the way. If interested you can see the work I did here:https://www.gmt400.com/threads/condenser-oil-cooler.59140/

One other thing...

Anyone know of the (ISC) on the 454 trucks? It speeds up the idle at first start. Was wondering if anyone knows where to source one. My current one is still functional but was wondering in the event it became non functional then what? It is the item in the following thread on the left...
https://www.gmt400.com/threads/help-me-id-these-parts-please.41025/

Part number -
GM 17084953 Idle speed control actuator


Each year I make up a list of stuff to replace (due to age). Thus far I've replaced the following items using Delco parts...

1. TPS
2. IAC
3. EGR (Linear)
4. PCV
5. Idle control speed solenoid
6. Purge valve
7. VSS sensors
8. Aux fan motor
9. Plugs
10. Wires 8.5mm ceramic
11. Shift solenoids A & B
12. Alternator
13. Radiator cap
14. Upper & lower radiator hoses
15. By-pass hose
16. Engine - frame ground braid cable
17. O2 sensor (single wire)
18. Belts (3)
19. MAP sensor
20. Ignition coil
21. Pick up coil (rebuilt distributor)
22. Cap
23. Rotor
24. ICM
25 T-stat (195F)
26. Rebuilt driveshaft
27. Front hubs
29. Ceramic pads
30. Master cylinder
31. Trans wire harness (internal)

Much appreciated everyone

Not sure why the pic of RV is upside down LOL!

[dave w]

I prefer having the original injectors cleaned / serviced vs. aftermarket new replacement injectors.

I recommend the services of Mr. Injector: https://www.mrinjector.us/

I've had good results with remanufactured injectors from GB Remanufacturing: https://www.gbreman.com/

[udidwht]

Much appreciated, when I get the TBI off I'll pull the numbers off the injectors. I'd indeed prefer to have them serviced as opposed to buying unknown ones.

Any recommendations on a fuel pressure gauge set up that connects to TBI?

[dave w]

Any recommendations on a fuel pressure gauge set up that connects to TBI?

I recommend "Not Installing" a fuel pressure gauge setup. Under hood temperatures will affect fuel pressure gauge accuracy.

I recommend modifying or buying a TBI fuel inlet fitting to allow easier access to check fuel pressure, if / when needed to check fuel pressure: https://marine-performance-parts.com/cfmtechfuelpsiguageadaptorforgmtbi2843505774.aspx

18997

[udidwht]

I recommend "Not Installing" a fuel pressure gauge setup. Under hood temperatures will affect fuel pressure gauge accuracy.

I recommend modifying or buying a TBI fuel inlet fitting to allow easier access to check fuel pressure, if / when needed to check fuel pressure: https://marine-performance-parts.com/cfmtechfuelpsiguageadaptorforgmtbi2843505774.aspx

18997
Appreciate that. I just picked up that adapter. I take it it replaces the inlet fitting on the TBI? Of the (2) fittings which is the inlet? Can't recall off the top of my head if they differed in size. I do know that both come from the rear side go into the TBI (left/right). I've go a pic I'll post up.

[udidwht]

Here's a link to a pic of the engine...

https://www.dropbox.com/s/ow3nt7k4hf4gimd/20180512_232309%5B1%5D.jpg?dl=0

I'm going to say the one on the right. Take that back looking at the pic closer it appears the inlet is on the drivers side.

[dave w]

Usually the inlet fuel line is 3/8" and the outlet (return) is 5/16". Likely the inlet fitting Will Not Fit the outlet fitting.

[tayto]

I add a schrader valve so i can use a regular automotive fuel gauge. I always thought having a gauge permanently mounted under the hood was a bad idea. I've also heard that heat affects the accuracy as well

https://www.dieselorings.com/schrader-valve-fuel-injection-rated-1-8-mnpt.html

[udidwht]

I add a schrader valve so i can use a regular automotive fuel gauge. I always thought having a gauge permanently mounted under the hood was a bad idea. I've also heard that heat affects the accuracy as well

https://www.dieselorings.com/schrader-valve-fuel-injection-rated-1-8-mnpt.html

Great! I'll pickup the schrader valve as well. Gone this far I may as well pick up a fuel pressure kit. Any recommendations?

[tayto]

i've had an OTC one for almost a decade p/n 5630. only thing i don't like it about it is it didn't come with a carrying case.

[udidwht]

I recommend "Not Installing" a fuel pressure gauge setup. Under hood temperatures will affect fuel pressure gauge accuracy.

I recommend modifying or buying a TBI fuel inlet fitting to allow easier access to check fuel pressure, if / when needed to check fuel pressure: https://marine-performance-parts.com/cfmtechfuelpsiguageadaptorforgmtbi2843505774.aspx

18997

FYI...that fitting leaked at the threaded areas on both the plug and the fuel schrader valve. Applied Permatex 2 prior to install. Reinstalled the OE fitting no leak. Contacted CFM for refund.

[dave w]

FYI...that fitting leaked at the threaded areas on both the plug and the fuel schrader valve. Applied Permatex 2 prior to install. Reinstalled the OE fitting no leak. Contacted CFM for refund.

Thank you for sharing your experience with the CFM fitting.

[udidwht]

Anyone know of a well made fitting that won't leak?

[tayto]

Anyone know of a well made fitting that won't leak?
did you make sure the small plastic seal was on the end?

[udidwht]

did you make sure the small plastic seal was on the end?

Did indeed. The leaks were at the fitting threads.

[Sledhead2]

So your saying the large steel fitting that threads into TBI leaked? or just the plug / gage ports?

[tayto]

ya there is 3 possible places it could leak from, where it goes into the fuel pod, where the hardline threads into or one of the ports to hook a fuel gauge up to. i have not used this fitting but they have been around for 15+ years, it is very possible you got a bad one.

it sounds like it's leaking from the npt ports, sounds like you used the wrong dope or didn't tighten them enough. my solution for a leaking npt fitting has always been just tighten it down more until it stops.

[udidwht]

So your saying the large steel fitting that threads into TBI leaked? or just the plug / gage ports?


The gauge ports. Permatex 2 used.

[Sledhead2]

Ok, Seeing it is the NPT gag ports get something like this shown below. My thinking is the gage ports were tapped a little to deep and that when you put plugs or gage in you are not getting the proper interference fit with the treads.

Permatex 2 is not gasoline résistance.

They do sell very small tubes of this stuff at home depot and other places

https://www.zoro.com/loctite-pipe-sealant-250ml-tube-medium-white-592tm-88568/i/G2235712/?recommended=true#specifications

[PlayingWithTBI]

Meh, I just used Teflon tape, had it on for ~4 years now with no runs, drips, or errors :rockon:
19060

[tayto]

ya i use the yellow "gas" teflon tape or actual thread sealant. I used that aviation form a gasket stuff in my younger days, but it doesnt seem to hold up well to oil.

[udidwht]

Ok, Seeing it is the NPT gag ports get something like this shown below. My thinking is the gage ports were tapped a little to deep and that when you put plugs or gage in you are not getting the proper interference fit with the treads.

Permatex 2 is not gasoline résistance.

They do sell very small tubes of this stuff at home depot and other places

https://www.zoro.com/loctite-pipe-sealant-250ml-tube-medium-white-592tm-88568/i/G2235712/?recommended=true#specifications
Permatex 2 is indeed gasoline resistant.


https://www.permatex.com/products/gasketing/gasket-sealants/permatex-form-a-gasket-no-2-sealant-11-oz/

[Sledhead2]

Permatex 2 is resistant, not gas proof. Get some Teflon tape or pipe sealant and you should be good to go.

[tayto]

https://www.permatex.com/products/thread-compounds/thread-sealants/permatex-high-performance-thread-sealant-50-ml/

this a real thread sealant. i use it on everything automotive from head bolts that go into coolant, intake bolts into oil, carb fittings etc

[udidwht]

https://www.permatex.com/products/thread-compounds/thread-sealants/permatex-high-performance-thread-sealant-50-ml/

this a real thread sealant. i use it on everything automotive from head bolts that go into coolant, intake bolts into oil, carb fittings etc

Have a tube of that and ordered some Gasoila.

[udidwht]

Update:

I used Permatex High performance thread sealant on the plug and Gasoila E-Seal on the adapter fitting. No leaks. We can right this one off in the history book.

[tayto]

good stuff