DIY Network

Fuel-Pump Replacement A Ford Ranger pick-up that refuses to start gets a thorough checkup and fuel-pump replacement. From "Weekend Mechanic" episode WKM-407

The old fuel pump and the new replacement. If Bruce's diagnosis is correct, a new fuel pump and fuel filter, and a little TLC for the battery, will get this pickup truck back on the road and ensure reliable start-ups.

One of the simplest systems on your vehicle is also one of the most vital and that’s the fuel delivery system. If you're vehicle doesn't have any get up and go, the problem may well be the fuel delivery system.

In this project, Weekend Mechanic host Bruce Bonebrake examines the fuel system of a Ranger pick-up truck that won't start. The project includes doing a fuel pressure test and checking the fuel pump relay to locate the problem to the fuel pump. After removing the truck bed to expose the fuel tank, Bruce removes the pump and replaces it with a new electric sending unit/fuel pump assembly. Then he retests the system, looks for fuel leaks and reinstalls the truck bed. A test drive confirms the successful repair.

The Problem

Our project vehicle, a 1991 Ford Ranger, won't start. It has gone from running sluggish and stalling frequently to the point where it simply won’t start. Bruce's guess is that there is a problem with the fuel delivery system, but that’s just a guess. Some simple diagnostics will give a more definitive answer.

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	Installing the new fuel pump.

Project Overview

Bruce Bonebrake inspects and tests the battery and fuel system to locate the no-start problem. He also tests the fuel-pump fuse. He then removes the truck bed and accesses and tests the fuel pump assembly, checking for ignition spark and using a noid-light test on the fuel injection system. Once he isolates the problem, he removes the faulty unit. Bruce installs a new fuel pump and sending unit, and replaces the fuel pump relay. He cleans up the battery, installs a new fuel filter, retests the fuel pressure and checks for fuel leaks. After verifying the successful repair, he re-installs the truck bed.

DIY Difficulty Rating for the Project: This job requires removal and replacement of one of the most critical elements of the vehicle's drive-train, and requires some serious safety considerations. We gave it a difficulty rating of 3 on a 5-point intermediate-level scale. At the outset, before isolating the extent of the problem, it's difficult to tell just how involved the repair will be. We allowed eight hours for this repair.

Important: Included here is a basic summary of the steps in this automotive procedure as shown in the episode. These steps are general guidelines that are applicable to most vehicles. With any particular vehicle, there may be procedures, specifications, settings, tolerances, components, etc. that are specific to that vehicle. There are also variations according to the type and brand of repair-kit or replacement parts you select. Always consult your vehicle's service manual when undertaking significant automotive repairs, and read and follow the manufacturer's directions and precautions that come with your kit or replacement parts.

Bruce tests the new fuel pump using a voltage meter.

Tools and materials:

In addition to standard auto-mechanic's tools (wrenches, ratchets, extenders, screwdrivers, nut-drivers, torque wrench, etc.), some of the tools required for this project include

general automotive tools
noid light injector tester
fuel pressure gauge
mutimeter
Aquaplex 524 dielectric anti-corrosion sealant
O-ring lubricant

Safety Alert: Always wear eye protection and ear protection, and follow proper safety precautions, when working with power tools. Also wear eye protection any time that you are working beneath a vehicle or around toxic or caustic fluids.

Safety Alert: As a standard safety precaution, always disconnect the vehicle's negative battery cable before you begin work on any electrical or mechanical components.

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