TBI fuel routing

**Mastiff** · 01-28-2015

After looking up some images of TBI throttle bodies, I see that I am missing the factory style adapters. I go straight to AN, and would need these:

to go to Saginaw. Does that type of fitting (TB end) have a name? I'm not sure what to search for.

**telecasterfool** · 01-28-2015

Hello- New Here, but wanted to comment- on my factory TBI setup- 1991 c1500- I replaced all my fuel lines with the poly lines custom made at NAPA. I traced the lines with string to get accurate lengths, gave the measurements to NAPA and they made them. I secured them with the factory bracketry on the frame, etc.

**fastacton** · 01-28-2015

Just go out to your local junkyard with 5/8" and 3/4" open end wrenches and grab them off of any throttle body. Don't forget the plastic sealing washers when installing! I don't know if there's a name for that type of fitting, maybe injector pod fitting? Where did you get AN adapters that replace these? I've only seen the kind that thread into these.

**Mastiff** · 01-29-2015

I bought my TBI conversion as a kit from a place called CustomEFIs a long time ago. The TBI came that way, but I think what he did was use tapered pipe thread instead of the proper fittings as a hack job alternative. I didn't know it was a hack until now.

**fastacton** · 01-29-2015

Hopefully they didn't damage the threads, but if they did, the only additional tool you need to pull the whole injector pod is a T25 Torx screwdriver.

**Mastiff** · 01-29-2015

FYI, came across this in searching. The correct way:

http://www.summitracing.com/parts/RUS-640813/

http://www.summitracing.com/parts/RUS-640803/

Still looking for one that goes to saginaw instead of AN. I'd rather pay than drive across town to get used parts... but I will if I have to.

**fastacton** · 01-29-2015

I just sent you a PM.

**1project2many** · 01-31-2015

I bought my TBI conversion as a kit from a place called CustomEFIs a long time ago. The TBI came that way, but I think what he did was use tapered pipe thread instead of the proper fittings as a hack job alternative. I didn't know it was a hack until now.

Ohboy... CustomEFIS hacks still showing up 16 years after the fact. <sigh> If you bought a complete "kit", did you get a new fuel pump and tested injectors or were you one of the early customers that received parts that were simply washed and sold after being pulled from the junkyard?

You have a K series vehicle. Exhaust was routed to the LH side of the transmission and the fuel lines were run up the RH frame rail. This kept fuel away from the heat from the converter. The fuel line on EFI equipped trucks was changed so the lines passed from frame rail to transmission at the rear of the transmission above the crossmember. The fuel lines didn't have to cross the exhaust because the trucks were not offered with dual pipes. The pipes or tubing would have been held with a bracket on the trans, another attached at the trans to engine bolts, and then it would have passed under the distributor, bent at the manifold, and attached to the rear of the throttle body.

If you have dual pipes you should use heat shields to keep heat away from the fuel line where they run parallel. Trust me on this... you don't want the fuel getting too hot in the tank. The safest way to connect the engine to the fuel lines on the frame is to route the lines to the front of the engine and up and completely skip trying to route the fuel across the exhaust. You could use pre-bent fuel line from an 85-ish carbureted vehicle for supply and you could use that line to fabricate a 5/16" line for return. Please consider passing on the compression fittings for a better connection such as inverted flare and a union. If you watch Ebay you can find the nuts for the TB. They also came in inverted flare versions on the earliest TBI cars such as the crossfire Vette in 82, F car in 82 - 83, and the 2.5 Pontiac vehicles in 82-83.

**Mastiff** · 02-05-2015

Thanks for the info. My plan is to route up to the front of the engine using the factory hard lines. I bought some of the recommended Dorman repair lines and I'll see if I can get them bent properly. If not, I'll get it close and hire inline tube to make them for me.

Yeah, CustomEFIs created problems that took years to sort out. I got a new fuel pump, but it wasn't a good one, and the TB I got turned out to have 305 injectors even though he gave me a 350 tune. It never ran right until I replaced the ECM completely with a unit from DynamicEFI and the pump with a Carter unit that could self prime properly. Now I have an in-tank pump.

Originally Posted by 1project2many

Ohboy... CustomEFIS hacks still showing up 16 years after the fact. <sigh> If you bought a complete "kit", did you get a new fuel pump and tested injectors or were you one of the early customers that received parts that were simply washed and sold after being pulled from the junkyard?

You have a K series vehicle. Exhaust was routed to the LH side of the transmission and the fuel lines were run up the RH frame rail. This kept fuel away from the heat from the converter. The fuel line on EFI equipped trucks was changed so the lines passed from frame rail to transmission at the rear of the transmission above the crossmember. The fuel lines didn't have to cross the exhaust because the trucks were not offered with dual pipes. The pipes or tubing would have been held with a bracket on the trans, another attached at the trans to engine bolts, and then it would have passed under the distributor, bent at the manifold, and attached to the rear of the throttle body.

If you have dual pipes you should use heat shields to keep heat away from the fuel line where they run parallel. Trust me on this... you don't want the fuel getting too hot in the tank. The safest way to connect the engine to the fuel lines on the frame is to route the lines to the front of the engine and up and completely skip trying to route the fuel across the exhaust. You could use pre-bent fuel line from an 85-ish carbureted vehicle for supply and you could use that line to fabricate a 5/16" line for return. Please consider passing on the compression fittings for a better connection such as inverted flare and a union. If you watch Ebay you can find the nuts for the TB. They also came in inverted flare versions on the earliest TBI cars such as the crossfire Vette in 82, F car in 82 - 83, and the 2.5 Pontiac vehicles in 82-83.