Relay Question - Fuel pump and more

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cabbygal
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Relay Question - Fuel pump and more

Post by cabbygal »

Hi everyone - I have replaced both fuel pumps and filter and am wondering if I need to replace Fuel Pump Relay as well?
How do I know if the relay is bad, (not functioning properly etc.)

What other relays should I replace : Issues Fuel pump and cold start?

Thanks :thumbup:
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Briano1234
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Re: Relay Question - Fuel pump and more

Post by Briano1234 »

Cold start on a Digi is either the Blue CTS sensor, The ISV, or the FPR.
Idle Stabilization Valve, (in front of the Throttle body) round cylinder with plug on it.
I have had them break wires, and get gummed up. (shooting carb cleaner through it let it soak.., then evaporate out)
CTS sensor has caused me all kinds of flakiness crappy idle, hard starts cold or hot.
FPR Fuel pressure regulator doesn't allow residual pressure, and can cause hard starts cold or hot, and stop running when warm.
The Bentley has tests to test fuel pressure that nailed a bad FPR for me.

The relay hasn't seemed to be an issue on my Digi's. Doesn't mean they can't go bad.

If you haven't replaced your ground cables I would do it. The digi is very finicky on grounds.
Briano

Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
You can lead a user to a link, but you can't make him Click.... :screwy:
cabbygal
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Re: Relay Question - Fuel pump and more

Post by cabbygal »

Thanks for the advice Briano - How do I replace grounds?
cabbygal
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Re: Relay Question - Fuel pump and more

Post by cabbygal »

ops one more thing Fuel pressure regulator - where do I find that?
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kamzcab86
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Re: Relay Question - Fuel pump and more

Post by kamzcab86 »

cabbygal wrote:ops one more thing Fuel pressure regulator - where do I find that?
Page 2 of http://www.cabby-info.com/Files/Misc/EngineDiagrams.pdf , #25. Looks like this: http://www.germanautoparts.com/Volkswag ... /Fuel/96/1 .
cabbygal wrote:Thanks for the advice Briano - How do I replace grounds?
Remove the main ground cables: http://www.cabby-info.com/electrical.htm#Ground (and click on the link at the bottom of that section for more Digifant ground specifics). Label the cables as you remove them, take said cables to your local NAPA and they'll fix you up with some new ones; install new cables when you get home, after cleaning the mounting points. For secondary grounds, get a wire brush and go to town on the ground connections (keep battery disconnected until you're done).

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CalAltaDubber
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Re: Relay Question - Fuel pump and more

Post by CalAltaDubber »

cabbygal wrote:Thanks for the advice Briano - How do I replace grounds?
Now there is a simple question that requires a big answer.

First let's clarify what Brian means. Chassis Ground is actually the chassis of your car, there are a number of wires that attach to the chassis and we collectivly refer to them as ground wires or grounds. In VW vehicles, the insulator on ground wires are generally brown.

The ground wire complete the various electric circuts. If the electrical current cannot flow through to chassis ground, the affected circuit will not work.

Due to the age of these cars (some are 30+ years old) corosion becomes a factor. Things like dirt, grease, rust, etc. affect the physical bond from the wire to chassis ground and cause the circuit not work or work intermittantly. Sometimes the cricuit will do funny things.

The fix is to make sure that wires and cables that attach to chassis ground have a good metal on metal bond. Some times the whole ground wire needs to be replaced. They need to be clean and free of corosion. That's what Brian means by replacing the grounds.

Two of the most troublesome grounds are:

1, the cable from the Negative (-ve) battery terminal. It runs from the battery to the transmission and then to the chassis. and

2, From the fire wall near the coil, to the valve cover on the engine.
Phil

'87 Cabriolet, "Topless Bunny"
'88 Cabriolet, "Posh Bunny"
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cabbygal
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Re: Relay Question - Fuel pump and more

Post by cabbygal »

Ok I know where the oil temp sensor is - and its disconnected - where do I find the cold start Valves (#28 on digifant diagram?)

Such great info thanks :)
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Briano1234
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Re: Relay Question - Fuel pump and more

Post by Briano1234 »

cabbygal wrote:Ok I know where the oil temp sensor is - and its disconnected - where do I find the cold start Valves (#28 on digifant diagram?)

Such great info thanks :)
there is no cold start valve on a digifant.
There is the blue cts sensor that is on the grille side of he car the water outlet.
There is the ISV that is in front of the throttle body and the back side of the valve cover.
The fuel pressure regulator is on the passenger side of he car behind the valve cover and attached to the fuel rail with 2 5mm allens and one on the side of the throttle body.
Briano

Yes as matter of fact, I have the Luck o'the Irish...everything I touch turns to fertilizer of the bovine variety.
You can lead a user to a link, but you can't make him Click.... :screwy:
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kamzcab86
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Re: Relay Question - Fuel pump and more

Post by kamzcab86 »

cabbygal wrote:where do I find the cold start Valves (#28 on digifant diagram?)
The ground cleaning image is merely providing examples of before and after cleanings; it simply shows what you can accomplish with a wire brush. Additionally, #28 on the Digifant diagram is the Digifant ECU... and, in fact, the cold-start valve on the CIS diagram is #32, not 28. :wink:

http://www.cabby-info.com/Files/Misc/EngineDiagrams.pdf <-- Digifant, page 2
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