Mechanics

QUESTION NO START

1994 Isuzu Rodeo

Electrical problem
1994 Isuzu Rodeo Question 6 cyl Two Wheel Drive Manual

I have a rodeo that won't start the other day while driving it suddenly died. I have checked for voltage at fuel pump there is none. I have also jumpered power to fuel pump and it will run that way but engine will not start. I sprayed starting fluid into throttle body and it will run. I have checked all fuses to pump and all relays but still no voltage to fuel pump. I have checked wires all the way up into the vehicle but from there Im lost any help would be appreciated
Avatar
Gregory1
February 27, 2009.



FUEL PRESSURE & FUEL PUMP RELAY TEST Fuel Pressure 1. Release fuel pressure. See FUEL SYSTEM PRESSURE RELEASE . Install a fuel pressure gauge between fuel pressure regulator and fuel distributor pipe. See Fig. 1 . Bleed air from fuel line going to pressure gauge. 2. Unplug fuel pressure regulator Vacuum Switching Valve (VSV) connector on right side fender skirt. This is a 4-wire connector with Black and Blue wires in harness. ECM controls VSV to cut vacuum to fuel pressure regulator during hot engine starts. 3. Start engine and measure fuel pressure at idle. Disconnect fuel pressure regulator vacuum hose. Note fuel pressure at idle with vacuum hose disconnected (no vacuum). Fuel pressure should be 42 psi (3.0 kg/cm 2 ). 4. If fuel pump pressure is low, check for fuel leaks, restrictions in intake side of fuel pump, leaking injectors, faulty pressure regulator or faulty fuel pump. If fuel pressure is high, check for restrictions in return line to tank or faulty pressure regulator. If pressure does not change when pressure regulator is disconnected, replace pressure regulator. Fig. 1: Installing Fuel Pressure Gauge Courtesy of ISUZU MOTOR CO. 5. Reconnect pressure regulator vacuum hose and check fuel pressure (with vacuum). Fuel pressure should be 35 psi (2.5 kg/cm 2 ). Apply battery voltage to VSV connector Blue wire terminal, and ground Black wire terminal (with vacuum). See Fig. 2 . Fuel pressure gauge should read about 42 psi (3.0 kg/cm 2 ). If fuel pressure is not within specification, check for defective VSV. 6. Disconnect and plug vacuum hose from fuel pressure regulator. Stop engine and ensure fuel pressure remains greater than 35 psi (2.5 kg/cm 2 ) for 4 minutes after engine stops. 7. If pressure drops, check for leaking injectors, faulty pressure regulator or bad check valve in fuel pump. If engine does not start, by-pass fuel pump relay to check for fuel pressure. 8. Remove fuel pump relay from underhood fuse/relay box. Connect a jumper wire between terminals No. 1 and 3 of fuel pump relay connector in fuse block. See Fig. 3 and Fig. 4 . 9. If fuel pump does not operate, check for battery voltage to terminal No. 3. If battery voltage is present, check for open in fuel pump circuit. If fuel pump operates with jumper wire installed, check fuel pump relay and relay energizing circuit. Repair as necessary. Fig. 2: Identifying Pressure Regulator VSV Terminals Courtesy of ISUZU MOTOR CO. Fig. 3: By-Passing Fuel Pump Relay Courtesy of ISUZU MOTOR CO. Fig. 4: Identifying Fuel Pump Relay Terminals Courtesy of ISUZU MOTOR CO. NOTE: Begin basic fuel system diagnosis with testing fuel pressure.Fuel Pump Relay 1. Power from charging circuit relay runs through fuse/relay box fuse No. 5 and diode box "A" to energize fuel pump relay. Relay is also energized from diode box "A" through oil pressure switch circuit in case of charging system failure. 2. When energized, fuel pump relay closes power circuit from main fuse No. 1, through fuse No. 2, through fuel pump relay to fuel pump. See appropriate wiring diagram in WIRING DIAGRAMS article. 3. To test relay, remove fuel pump relay from fuse/relay box on right fender panel. Using jumper wires, ground terminal No. 4 (Black wire) and apply battery voltage to terminal No. 5 (White wire). See Fig. 4 . There should be continuity between terminals No. 1 and 3 with relay energized. If continuity is not present, replace relay.


http://www.2carpros.com/forum/automotive_pictures/62217_rodeoa_1.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_rodeoab_1.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_rodeoc_1.jpg



http://www.2carpros.com/forum/automotive_pictures/62217_rodeod_1.jpg


Merlin2021
Feb 27, 2009.
Ok after jumpering 1, 3 connections to get fuel pump to run it will but engine will still not start even with fuel pump engaged and running

Tiny
Gregory1
Feb 27, 2009.
Check for spark and compression, one is missing. Let me know. Look on our how to section at the top right of the page for help with those two.

Merlin2021
Feb 27, 2009.
It has spark and compression it will start and run if I spray starting fluid in the throttle body

Tiny
Gregory1
Feb 27, 2009.
I also checked ignition module and ita was okay. I Ichecked for continuity of the wires from the fuel pump all the way to the computer. On the other side of the harness I have voltage. I was wondering if the computer could be at fault I have never heard of one failing while driving

Tiny
Gregory1
Feb 27, 2009.
Can you give me the engine size? And have you tried to retrieve any fualt codes? Here's how to do that, post any codes found.


http://www.2carpros.com/forum/automotive_pictures/62217_isuzu_1.gif



http://www.2carpros.com/forum/automotive_pictures/62217_isuzua_1.jpg


Merlin2021
Feb 28, 2009.
I have absolutely no power to the computer I have checked all fuses and relays they all checked out fine I also have pulled the plugs from computer and there seems to be voltage to the computer but I don't know which color wire is the power wire so basically there is no way to check for any codes

Tiny
Gregory1
Mar 2, 2009.
UNDERHOOD FUSE & RELAY PANEL IDENTIFICATION Fig. 2: Underhood Fuse & Relay Panel Identification Courtesy of ISUZU MOTOR CO. Fusible Link Identification  A - 80 Amp (1991-92 3.1L)  A - 60 Amp Main-1  B - 30 Amp Main-2  C - 30 Amp (1993-94) ECM (3.2L)  D - 30 Amp Condenser Fan (A/T Models) Relay Identification  1 - Headlight Relay  2 - A/C - Heater Relay  3 - Starter Relay  4 - A/C Compressor Relay  5 - Charge Relay  6 - Fuel Pump Relay  7 - ECM Relay  8 - Wiper Relay Fuse & Circuit Breaker Identification  1 - 15 Amp (1991) ECM, Fuel Injection System  1 - 15 Amp (1992-94 2.6L) ECM, Fuel Injection System  1 - 10 Amp (1992-94 3.1 & 3.2L) Heated Oxygen Sensor, Fuel Injection System  2 - 20 Amp (1991-92) Fuel Pump  2 - 20 Amp (1993-94 2.6L) Fuel Pump  2 - 15 Amp (1993-94 3.2L) Fuel Pump  3 - 10 Amp (1991)  3 - 15 Amp (1992-94) Turn Signal Lights, Hazard Warning Flasher Lights  4 - 10 Amp Horn, Door Locks  5 - Not Used (1991 3.1L)  5 - 10 Amp Charging System, Charge Warning Light WARNING: Always disconnect battery ground cable before servicing "high- current fuses. It is recommended that "high-current" fuses be replaced by a qualified technician. Page 1 of 2 FUSES & CIRCUIT BREAKERS -1994 Isuzu Rodeo LS 6 - Not Used (1991) (1992-93 2.6L)  6 - 10 Amp (1992-94 3.1L & 3.2L) A/T Interlock System  6 - 10 Amp (1994 2.6L) Heated Oxygen Sensor, Fuel Injection System  7 - 20 Amp Heater/Air Conditioning Blower Controls  8 - 10 Amp Air Conditioner Compressor Controls  9 - 10 Amp Right Headlight  10 - 10 Amp Left Headlight


http://www.2carpros.com/forum/automotive_pictures/62217_isuzfuse_1.jpg


Underhood fuse block swap out relay #7 thats the ECM relay.
Ground Circuits Using a DVOM, touch negative voltmeter lead to a good ground. Touch positive voltmeter lead to each ground terminal. With vehicle running, voltmeter should indicate less than one volt. If reading is greater than one volt, check for open, corrosion and loose connection on ground lead. See ECM GROUND LOCATION table for ECM ground location.
Page 1 of 1 SYSTEM/COMPONENT TESTS - 2.6L EFI -1994 Isuzu Rodeo LS


http://www.2carpros.com/forum/automotive_pictures/62217_ecma_1.jpg

ECM Relay 1. Remove relay from connector. Test for continuity between terminals No. 1 and 2. See Fig. 6 . Continuity should exist. Test for continuity between terminals No. 3 and 4. Continuity should not exist. 2. Apply battery voltage between terminals No. 5 and 6. Test for continuity between terminals No. 1 and 2. Continuity should not exist. Test for continuity between terminals No. 3 and 4. Continuity should exist. Replace relay if defective.

Merlin2021
Mar 4, 2009.