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79 928 fuel system..

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Old 03-18-2017, 06:41 PM
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Speedtoys
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Default 79 928 fuel system..

Can you use the filter/pump from an S3-S4 on this car?
Old 03-18-2017, 11:21 PM
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Dennis Wilson
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The CIS fuel system uses a higher pressure pump than later models.
Old 03-18-2017, 11:39 PM
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hlee96
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I think someone's been using an S4 pump in Saudi Arabia in place of both pumps without any issues. Forgot his username. He posts a great deal, so I'm sure he will chime in.

Hoi
Old 03-19-2017, 08:49 AM
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Guy
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I ran a CIS car using the later tank and pump set up for quite some time. The CiS pump has a built in check valve while it is in the banjo on later pumps so be sure to address that issue when trying this. It's possible but less than optimal
Old 03-20-2017, 07:54 PM
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CIS needs to see a system pressure of 5+Bar (75 Psi+),So you need a pump with that pressure rating.
Old 03-20-2017, 10:27 PM
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Originally Posted by STRIKEMASTER
CIS needs to see a system pressure of 5+Bar (75 Psi+),So you need a pump with that pressure rating.
Good to know, totally new system to me.

Its a car with some work done to the fuel system in the rear..that could end up in an S3 config, or back to 79 config...for about the same price I think.

I already have in the parts the came with it, an S3 pump/filter/mounting hardware.

Gotta drop the tank and see what's really all going on.
Old 03-21-2017, 01:43 PM
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The filters are the same apart from a screw in connector on one end of the filter - remove the screw in connector and you are good to go on the filter.
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