Jims Performance

Telephone - 410-465-9569

Toll Free Order Line 1-877-465-9569


Bench testing a 93 harness w/4L60E
See a 87 to 91 harness
See a Vortec TPI intake
See a Vortec TPI in a 1995 Truck with Commander 950

The first production V-8 THROTTLE BODY INJECTION (TBI) appeared on General Motors vehicles in 1987 in the pick up truck. This was a great upgrade from the carburetor and a step in the right direction for dependability and economy in the work truck. Since then we have converted many TBI harnesses into TPI harness so one can use a TPI in its place.In order to do such a conversion you will remove your ecm and wiring harness from the pass side of the truck.You will also find it is shared with another harness that simply unplugs from the firewall on drivers side and seperates from the lighting harness.This is what we need sent in for the 2 day modification.In fact, most customers get their harness back before they even complete the mechanical work needed.We set the harness up to run on a 1227730 speed density ecm and a custom prom.The harness is reworked and fitted to a TPI unit in that we assure a perfect factory fit when you re-install it into the truck. The in-tank fuel pump of course needs to be replaced as well with AC-DELCO#241 which is available thru us for $79.95.It is a direct replacement and will set your system up for TPI.If serp belt is on truck the tensioner will in the way of a K&N air filter so you will need aluminum shells from an 88-92 Camaro to hold your same accessories but it relocates the tensioner down and out of the way.On trucks with the 2 V belts and a small serp for alternator the only item you will need is our upper alt bracket to re-support the alt after the TPI is in place.This harness mod cost $250

If you have a 1993 and up truck and want TPI it is a little tougher but we can still do the conversion.The harness still gets removed as mentioned above and still will be modified however we leave the stock ecm in the harness to control the 4L60E. We then set up the harness to accept another ecm (1227730) which will share some signals with the stock ecm so we have both TPI engine control and 4L60E control.When we do this we provide a second ALDL so the TPI system can be scanned with a scan tool and your other DLC plug under your drivers dash now will remain the same for future use by GM.There is enough room for the 2nd ecm behind the glove box.This harness mod cost $300


Installing an LT1 into the truck has been done as well.In these applications the stock harness is still pulled and the LT1 harness for the engine is reworked and merged into the stock harness becomming one harness to be reinstalled.This is a tougher conversion due to AC hung low on pass side and coolant hoses but can be done.We can remove VATS from the LT1 ecm as well and set the system up so you can use Hypertech programmers as needed to make your own changes rather than charge you to flash the memory.This harness Mod cost $400 and takes 5 days.

Fuel Pumps

The OEM fuel pump for TPI/LT1 is an "in tank" fuel pump with an operating rating of 50 PSI and 24 GPH. This pump is recommended for all vehicles with in-tank pump mountings. We also offer a chassis mounted fuelpump which has an operating rating of 60 PSI and 30 GPH. This pump is also an AC DELCO unit. It is important to note that Throttle Body Injection systems operate at 12 PSI. Almost all carbureted systems operate at low pressure utilizing a mechanical pump. An electric pump is definitely required as referenced above for all Port Injection systems. A return line is required to the fuel tank. A 3/8 or 5/16inch supply line is required. 3/8 is recommended. 5/16 inch is recommended for the return line. The fuel tank must be vented so as not to buildup pressure. Recommended location for the fuel pump is close to the fuel tank.

Programmable ecm and TPI

We can also convert a truck harness to run on a Holley Commander 950 ecm or a DFI ecm as a direct plug in. When we convert your harness into a TPI configuration we will also repin your harness for the programable ecm.We also bench test the system.Some applications will require a speed interface module if speed processing was handled by the stock ecm.
Telephone - 410-465-9569
Toll Free 1-877-465-9569

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