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Chris (aka-Moose)
Chris (aka-Moose), Technician
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Isuzu Amigo: I need to replace the fuel pump relay on an Isuzu

Customer Question

I need to replace the fuel pump relay on an Isuzu Amigo 1992 - 4X4 5 speed manual.
Submitted: 4 years ago.
Category: Car
Expert:  internal88 replied 4 years ago.

internal88 :

Hello and welcome

Do you have the 2.3 or 2.6 liters engine.

internal88 :

So you want to know the location and part number?

Customer :

I am not sure which engine. One minute

I do know it's a five speed manual 4X4 if that helps

Customer :

I can't see where it says what size motor

internal88 :

ok give me a minute, I will help you.

internal88 :

OE part number is 8942184970. It is a 5 terminal relay, cost $33.50.

The relay is in the relay box on the right hand side. fender apron.

When the ignition is switched "ON" (engine not running), the ECM energizes the fuel pump relay for two seconds, causing the fuel pump to pressurize the fuel system. If the ECM does not receive ignition reference pulses (engine cranking or running) within two seconds, it will de-energize the relay, stopping the fuel pump.As a back-up system, the fuel pump can also be turned "ON" by the oil pressure switch. If the fuel pump relay fails, the oil pressure switch will run the fuel pump. However, an inoperative relay can result in long cranking times, especially if the engine is cold. The switch will not turn the pump "ON" until oil pressure reaches about 28 kPa (4 psi).

internal88 :

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internal88 :

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internal88 :

Is this helpful?

Customer :

the fuel pump won't stop running when the engine is turned off and we figured it was the relay

internal88 :

that is right.

Customer :

just let me run outside again... be right back

internal88 :

ok

Customer :

diode box a and b are not installed, is that a problem

internal88 :

diode box a and b?

internal88 :

what do you mean?

Customer :

on the schematics you sent me showing where the relays are it shows diode box a and diode box b, those positions are empty.

internal88 :

Those relays are not necessary.

Customer :

good.. thank you. I'm heading out to buy a new relay, thank you for your help

internal88 :

some of the relay slot is not made for US

internal88 :

US market

Customer :

that would explain empty places

internal88 :

Please don't forget to rate me, thanks.

Customer :

it's a salvage vehicle for farm use, but the fuel filter burst open the other day because the fuel pump kept running.

internal88 :

ok

internal88 :

i see

internal88 :

That's correct the fuel pump relay gone bad.

Customer :

thank you for your help

internal88 :

you are welcome

Customer :

Thank you. I am heading to the local Auto Parts store to see if they have one.

internal88 :

I hope they have the part. If they don't try parts.com

Customer :

They ordered one in, but I switched the one for the headlights and the pump kept running. I am getting the new one tomorrow, hopefully that will fix the issue. If not do you have any idea of what else could be causing the problem?

internal88 : Iam pretty sure is the relay . If not , I will look into the fuel system systematic for you. Let me know tomorrow.
Customer :

the new relay didn't solve the problem.

internal88 : So what exactly is the problem now? Can you remove the fuel pimp connector and inspect the terminals.
internal88 : I will be back
internal88 :

Can you disconnect the fuel pump connector.

internal88 :

Engine off - the connector to the fuel pump should have no voltage.

internal88 :

please let me know the results.

internal88 :

I'm trying to find out if is the main relay or the fuel pump relay.

internal88 :

I meant the fuel pump not the fp relay.

internal88 :

Can you tell me if the truck is 2.3 or 2.6 liters engine?

internal88 :

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internal88 :

There is a chance you have a bad ignition switch. The fuel pump is thinking the ignition is constantly staying on.

The fuel pump relay should only be on when it start or crack. If the key is off and the relay is energize then you have a bad ignition switch. Start with that.

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