TBI fuel routing

**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.

billygraves · 01-29-2015

Look, GM ran the fuel lines through the tunnel for 2 reasons. Keep the cost low and crash worthiness. Cost saved a few feet of each line to the front of the frame and then up to the top of the engine. Why the Teflon SS lines for a few years? The change to rubber was a employee suggestion that GM use floermaster rubber hose in stead of Teflon ss as the flex portion. This netted the man 20k from the suggestion plan. (If the reduction in steel line in the tunnel might have been 50 cents per truck, multiply this times xx million trucks and meets the crash barrier test....)
The tunnel routing of the line becomes a fuel heater (in the summer) as the 80's F-Car had. This generates a tremendous amount of vapor to deal with and larger canisters.
If this were my own, I would run the lines as the factory did along the frame rails and use Parker Teflon SS hose to connect the engine to the lines. Parker has lower cost than Earls, ect. (The AN rubber may not stand up to Ethanol and it does break down. A friend @ GM proving grds used this AN rubber on his 58 Corvette for fuel lines. 7 years later he put in EFI. He had a section of the line off the car and we were in the garage. He was flexing the line and he held it up to look at how long it was. On the floor were a small pile of rubber from inside the AN hose. We split the SS and cut the line open. None of us use this anymore, especially for trans cooler hose.

**Mastiff** · 01-29-2015

I started this thread because I couldn't (and still can't) picture how to get the flex line past the pipes safely and cleanly. I have long tube headers too, which complicates matters. On another forum I found a guy who did what I had in mind, using the factory lines all the way to the mechanical pump area, then flex to the engine and steel over the top of the motor to TBI. A clever trick in addition is to put a canister fuel filter where the mechanical pump used to be, for an overall slick install. My plan is to copy that idea and stop having flex line cable tied up the back of the motor. I'll look into the Parker Teflon. I've had hoses break down quickly and don't want that again.

**tayto** · 01-29-2015

why not just get factory lines off a tbi blazer? tank has sump and in tank pump. done deal.

**Mastiff** · 01-30-2015

Originally Posted by tayto

why not just get factory lines off a tbi blazer? tank has sump and in tank pump. done deal.

I already have a TBI tank and in-tank pump. I don't know if factory lines will fit past my headers since I've never seen a pic of how they go. Lots of people have described it to me, but the fine details matter. Also don't know where to buy them except 25 year old ones from a junk yard.

**ony** · 01-30-2015

IF YOU GO TO THE JUNK YARD YOU MIGHT FIND A TRUCK STILL INTACK AND SEE WHERE THE LINES ARE ROUTED, AND FIND SOME PARTS THAT YOU WANTED.

**lionelhutz** · 01-30-2015

It's easy to jump from the frame rail to the firewall by going above the header. That's how mine are routed. Buy repair lines like I linked and adapt braided lines to them for the run between the frame rail and the engine. You can get a compression or flare to AN fitting. It's not rocket science.

**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.

**Woods** · 02-06-2015

Originally Posted by fastacton

Ditch the AN adapters and get Dorman part numbers 800-151 and 800-153. These are "repair" lines that give you factory TBI fittings on 3/8" and 5/16" hard lines with compression fittings to connect to more hard line.

I am looking at those part#'s cause I could use a set of those. Do these come with the compression fittings? I seem to be finding mixed information on that. Some show pictures with a hose fitting on the end with the same part# so I am a bit confused.
Thanks