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Ellison Throttle Body Injector

Appendix C - Troubleshooting Guide

Symptom Possible Causes
Dying at idle with engine cold. Not unusual - idle setting must be adjusted when engine is warm. Without engine heat to evaporate idle fuel, the throttle must be opened slightly until the oil warms up.
Dying at idle when engine is warm on a warm or hot day but idle behavior stable on cool days or when engine is cold. Vapor formation caused by fuel lines absorbing engine heat when fuel rate is very low.  This problem is common with fuel injection systems and may be prevented by:
  1. Careful insulation of all fuel system components
  2. Blast cooling pumps, gascolator, filter, and flow transmitter.
  3. Install vapor return line to tank per EFS instructions.

Leak in fuel system on suction side of fuel pump allowing air to be drawn into fuel systems.

Idle setting seems to change. Throttle slipping or unsupported.

Ice:  apply carb heat.

Induction air leak between TBI and cylinders.

Leaking throttle slide seal.

Acceleration unsatisfactory Idle mixture too lean.

Induction air leak between TBI and cylinders.

Mixture not in full rich position.

Metering tube holes clogged.

Flat spot in throttle response when slowly opening throttle. Plugged holes in metering tube.

Induction air leak between TBI and cylinders.

Excessively rich at idle conditions of visible moisture or high humidity. ICE - apply induction heat.
Excessive idle RPM when idle throttle adjust screw is backed out fully. Induction air leak between TBI and cylinders.
Excessive leanness at high power.
  1. Full rich metering tube adjustment set too lean.
  2. Inlet air turbulence caused by bad airbox configuration.  Review section 2-9 of this manual.
  3. Fuel system flow capacity limit (see section 2-2, item H).
  4. Induction gasket or airbox flange blocking bellmouth reference probe.
  5. Leak in fuel system on suction side of fuel pump such as leaking primer or pump lines which allows air to be drawn into fuel system.
  6. Clogged fuel filter.
  7. Clogged metering tube holes.
  8. Vapor formation.
  9. Defective fuel pump.
Leaking fuel after engine shutdown:
  1. Less than 1 tablespoon
  2. More than 1 tablespoon (leak continues)
  1. Normal.
  2. This sometimes occurs on new TBI units but should disappear after fuel inlet control valves have seated (usually within the first 10 hours of operation).
Engine roughness at wide open throttle. Same cause as excessive leanness at high power.
Engine dies when throttle is slowly opened from idle. Induction air leak between TBI and cylinders.
Engine roughness at wide open throttle (WOT) that tends to smooth out when mixture is leaned. Inlet turbulence (see section 2-9) or rich stop set too rich.
Rich idle that persists after idle mixture screw is fully seated. Indicates worn slide seals caused by ingestion of unfiltered air.  Return TBI to Ellison Fluid Systems, Inc. for repair.
909-906-1472         Ellison-Fluid-Systems, Inc.

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