Fuel Pump Troubleshooting - Part 2
I can't count how many times over the years that I get questions about troubleshooting a fuel pump both mechanical and electric. And some of these are very expensive. And guessing wrong is both annoying and frustrating. Because of this I have included a collection of tech references straight from a variety of sites to try to shed some light on this problem and attempt to help get it right the first time. A little front end info can be invaluable in making the right decision.
Electronic Fuel Pump Failure - In-Line and In-Tank
- Loss of current or low voltage
- Corroded, loose or broken wiring
- Faulty relay and relay terminals, inertia switch, oil pressure sending unit, ground, or engine control module
- Dirt, sediment, rust or other debris in the tank can wear or lock up the pump, or cause the pump's check valve to stick open, causing hard starting due to loss of pressure when the engine is shut off. Rust is caused by condensation, which occurs during cool, humid weather when the fuel tank is low.
- Alcohol- or ethanol-enhanced gasoline or alcohol fuel additives can loosen deposits in the tank that can clog the strainer.
- Normal wear, or wear caused by consistently low fuel levels and non-lubrication, can lead to accelerated wear or even pump damage. Wear can also be caused by running the pump at excessive pressure caused by a faulty regulator or check valve, a crimped line or a clogged inline fuel filter.
Driveability problems with electric fuel pump applications - Complaints of no fuel, rough idle or lack of performance should be investigated as follows:
- Ethanol – Certain materials commonly used with gasoline are totally incompatible with alcohols. When these materials (such as aluminum) come in contact with ethanol, they may dissolve in the fuel. This may damage engine parts and result in poor vehicle driveability. Even if parts do not fail, running ethanol in a non-ethanol compliant vehicle may cause deposits that could eventually harm the engine. [See note below]
- Contaminated Gasoline – Water retention in contaminated gasoline can cause corrosion to fuel pump conductors.
- No Fuel Delivery – Many vehicles equipped with fuel injection have two electric fuel pumps: a low-pressure feed pump located in the tank and a high-pressure frame-mounted delivery pump.
Check the following on no-fuel complaints:
- Blown fuse on one or both pumps. If a fuse is blown, determine the cause before replacing it.
- Tripped inertia switch located in trunk area (reset by pushing plunger)
- Shorted RFI filter on in-tank pump
- Poor Acceleration and/or Driveability – On driveability complaints check for:
- Defective fuel pressure regulator
- Restricted fuel filters
- Pinched or deteriorated fuel hoses
- Rough Idle – Poor idle quality could be the result of:
- Dirty injectors
- Cracked or disconnected vacuum hoses
- Ignition problems
- Engine compression problems
Many times a rough idle condition can be cured by the use of high-detergent gasoline. Most stations now offer this grade of gasoline, which is recommended by vehicle manufacturers. Remember, for trouble-free fuel system operation, use only replacement parts manufactured to original equipment quality standards.
E-85 what is this and what does it mean to me and my car. Find out here.
All sorts of nasties can be in the tank and fuel syatem. What are they and how can I deal with them. Find out here.
- Basic electric pump general instructions
- This Carter PDF doc covers a variety of general good practice notes on installing both in-tank and in-line pumps. Link
- Diagnosing Low Fuel / No Fuel problems
- This page gives you a general direction on how to diagnose these problems. It is not aways the pump! Link
- Carter Bulletin #1608 Common causes of electric in-tank fuel pump failures
- Some insights into the common documented issues of pump failure. Once again not always the pump. Link
- Carter Bulletin #1611 Complete in-tank module replacement for GM vehicles
- Some things to watch for on GM TS and replacement Link
- Carter Bulletin #1620 Comprehensive Guide to Proper Fuel Pump Installation
- Just like it says. A complete guide to R and R a pump. Link