Jeep EFI Upgrade Tips: Howell EFI Conversion Kit Helps Kick The Carb!
No vehicle on the road (or off road) benefits more from swapping from a classic carburetor to electronic fuel injection than a Jeep After all, eliminating those angle sensitive float bowls that can starve an engine for fuel and creating an engine system that can adjust to the altitude of the climb by richening and leaning out the fuel delivery is every Jeep lover’s dream.
Howell EFI offers eight different kits for most Jeeps built between 1982 and 1993 that originally came with carburetors. Best of all, for the street-driven Jeeps, the conversion kits include full emission compliance within strict Air Resources Board mandates. That means owners will never have a problem with the local regulators when checking emissions compliance.
“The Howell EFI conversion kit integrates the critical charcoal canister and the EGR systems and eliminates the need for the air pump and other engine cluttering components,” stated Troy Brown, Howell EFI Tech Director. “What we do recommend is that owners who install this kit go on our website and print out Air Resource Board Executive order D452 and keep this two page document in their Jeep. This document shows that our system is emissions complaint and should handle any issues they encounter.”
Pictured from top to bottom: Throttle body installed in place of carburetor, wiring through firewall, ECM installed in glove box, fuel pump and filter assembly. Click image for larger view.
The Howell EFI conversion kit includes everything you need to install the kit including the GM Throttle Body, reprogramed computer, high flow electric fuel pump, fuel filter, MAP sensor, all hardware, clips, mounts and most importantly, the custom factory-look wiring harness that uses better-than-factory components and wiring. Howell estimates that most of their Jeep conversion kits will take between 8 and 10 hours to install depending on your level of skill and the condition of your Jeep.
Key points to the installation include modification of the fuel system. Fuel injection systems require both a fuel delivery line and a return line, both running the length of the vehicle from the fuel tank to the engine. The recommendation is that this line be 5/16-inch diameter line, either braided steel or hard line. Rubber fuel line or steel line, if so desired, should be used but when using steel line, small sections of rubber hose are allowable around the new fuel filter and fuel pump to make them easy to service when needed. Many owners choose to mount these parts inside the transmission protection pan to avoid the buzzing noise notoriously emitted by electric pumps. Mounting the pump with some kind of rubber foam spacer where it touches the pan will keep the noise to a minimum.
The MAP (Mass Air Pressure) sensor supplied with the kit is a key component to proper operation. Howell EFI offers two types; one that can be simply installed off the TBI unit with a stiff piece of rubber hose or a second type that must be mounted in a downward facing angle with vacuum pointing towards the ground and the sensor mounted above the TBI unit itself on a bracket or the firewall. When reviewing your instructions, the MAP mount for your component will be noted.
Your Jeep’s computer is located within the interior behind the glove box. The dashboard on the passenger side must be loosened to allow for removal of the glove box. Once it is removed, the computer is easily located. Two nuts located on the engine side of the firewall must be removed to release the computer. Once it is free, gently remove the original equipment wiring harness junction from the computer.
The CTO (Coolant Temperature Override) switch is mounted on the engine block just below the intake manifold. It will be retained for any conversion and must be working properly. These switches are notorious for leakage, so if yours is showing its age it must be replaced. In addition, the original engine block mounted mechanical fuel pump will be removed and replaced by the block off plate supplied with the Howell EFI kit. The original pump rod stays in the block or the engine or oil pressure will not be correct. Make sure that the Howell plate is well sealed or oil leaks will occur.
For those looking for an overview of the system and owner experiences, YouTube-based instructional videos are readily available. “We have Jeep owners who go the full route and take out all of the original wiring loom and those that just tuck the unused original wiring away in the dashboard after heat shrinking the powered wires so they don’t ground out,” said Troy. “It is at the discretion of the builder as to how much or little they want to do – as with any vehicle modification. We honestly estimate the total install to not be longer than 10 hours from start to finish. The key is to study the schematic supplied with the kit and call our tech line if there are any questions.”