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dave833

90 Loyale Fuel Pump question

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I have a 1990 Loyale turbo 4wd wagon which fails to start about once every 10-15 times because the fuel pump doesn't come on at all when I turn the key. Turning the ignition off/on a few times (or more!) usually results in the fuel pump coming to life and the car starts. Any suggestions? I thought it might be a fuel pump relay, but I don't know where to find it or what it looks for.

 

Thanks!

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i had a buddy with a chevy truck that had a worn ignition switch..would only make good contact after turning key over a few times..same symptom..wouldnt engage fuel pump..

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It could very well be the relay. It may also be due to the ECU turning the pump off because it is not seeing timing pulses from the Crank Angle Sensor. This is in the distributor. The next time this happens I would check the ECU for trouble codes to see if there is another problem besides the relay. If the relay is not working, I don't think you will have a code for that problem but you will if there is a CAS problem.

 

I would purchase a service manual for your car. It will pay for itself in no time helping fix problems like these.

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If I am not mistaken the fuel pump should run for app. 1.5 sec.

each time the key is turned from off to the run position

This no doubt "recharges" the fuel system pressure for any leak down that may have occured during the off period.

It could be

1) What Glen was referring to - the ECU not providing the negative side of the fuel pumps electrical connection.

2) the fuel pump relay not providing the positive side to the fuel pump electrical connection. This, I believe, is not controlled by the ECU but a direct connection from ignition switch to the fuel pump relay.

You or some one friendly with a voltmeter can trouble shoot this.

The relay looks like this and you may have to take down the ECU to get to it (note the ECU mounting points are slotted - you do not have to remove the three 12 mm nuts)

 

 

relayEA82.JPG

Hope this helps

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Originally posted by Skip

1) What Glen was referring to - the ECU not providing the negative side of the fuel pumps electrical connection.

It's a bit more complex than that, I'm afraid.

 

If it's a model equipped with automatic shoulder belts, then there exists another box that controls the fuel pump relay's ground instead of the ECU. I can't find a wiring diagram of this circuit in AllData, but here's the "alternative" fragment:90_Subaru_FuelPumpWiring_a.png

 

 

Also, there's a TSB on checking this Fuel Control Unit:

 

90_Subaru_FuelPumpCutRelay_a.png

 

 

Click on each image for a larger version to print.

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Quite by accident, I found another reference to this:

 

http://216.239.53.104/search?q=cache:LdmUiC_gdQcJ:www.smpcorp.com/download/view/tt1q00.pdf+subaru+diagnostic+codes+1993+loyale&hl=en&ie=UTF-8

 

SUBARU-1989 TO 1993 W/1.8L ENG.- NO START If you are working on an '89 -'93 Subaru L series or Loyale with a 1.8L single or multi-point fuel injection system that's a no start, has spark and fuel injector pulse, but no fuel pressure, here's something to keep in mind. Before investigating the fuel pump circuit, please be aware that most wiring diagrams for these vehicles indicate that the blue and black wire from the fuel pump relay coil is grounded by the ECM. That would be at pin #47 for the single point injection system, and pin #6 for the multi port system. This is true for vehicles that do not have automatic shoulder belts. For models equipped with automatic shoulder belts, the fuel pump relay's winding is grounded by a Revolution Sensor or fuel cut unit. This unit is similar in operation to the fuel pump relay used on many European models (for example, Volkswagon). When this unit receives a tach signal from the ignition coil negative terminal, it grounds the blue and black wire, thus energizing the relay. The Revolution Sensor is usually located just above the hood release cable handle.

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