# fuel pumps



## ziggydub628 (Feb 10, 2010)

so this new search thing is really complicated to me. and i have a few questions about fuel pumps.. 

i have been told my 85 golf (cis-e?) has two fuel pumps. true or false? 
if true, how do i test the in tank pump i have been told exists? there is nothing in my book about one being there (cant afford bentley so i have a haynes). 
when i test my in line fuel pump, i get no reading when i connect a volt meter, but when i put the plug back into the pump it will start. other times the pump wont turn on at all. i have a brand new relay in but have also tried several from other cars that are the same, and bridging the relay. any suggestions to my problems?


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## ziddey (Apr 16, 2006)

yes, there's the intank pump as well as the main pump under the car. 

I'm assuming you're using a horn relay to keep the fuel pumps going? The intank pump is cheap, and worth replacing as assurance in keeping the main pump happy (main pumps are generally fairly reliable, and tend to fail when the intank pump fails, causing excessive strain on the main pump). Plus, when you yank the intank pump, you'll probably find all the rubber is just about disintegrated. Would make a good time to change all the rubber hoses for new nitrile hoses, that'd be capable of handling e10 or even e85 for long periods.


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## WaterWheels (Aug 14, 2005)

As stated, yes there is an in tank pump (transfer pump). If you open the trunk (rear hatch), remove the mat or carpet and look behind the rear seat by the right rear wheelwell (maybe two words) you will see a round plate held in place with three screws. Remove the three screws and lift the plate to uncover the fuel level sending unit and transfer pump. Everything is in the tank and only the mounting and electrical connection plus fuel lines can be seen. There you can test for power to the pump, test your fuel gauge if need be and by removing the feed line and using a manual as a guide test the output of the transfer pump. I do find it hard to believe the Haynes does not have such basic information in it, but . . .

How you tested the power to the pump could make a difference. A real or defined problem is not posted that I can see. You say you can't get a power reading at the pump but say it starts when plugged up. You also state at times the pump will not run at all, but don't explain just how you discovered this? Can you go into some detail on what the problem is?


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## ziggydub628 (Feb 10, 2010)

WaterWheels said:


> You also state at times the pump will not run at all, but don't explain just how you discovered this? Can you go into some detail on what the problem is?


There have been times that I will go out to my car and try and start it so i can leave for work, but when I kick on the ignition, the fuel pump doesnt start, and the engine will turn over but wont fire as if not getting fuel.

I'm assuming you're using a horn relay to keep the fuel pumps going?

Not that I know of, the relay matched the description of the one in my book, and was an oe replacement of the one i had as fas as i know..


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## WaterWheels (Aug 14, 2005)

I also want to get this correct too, when you bridge the two large sockets, about 3/8" wide, where the fuel pump relay plugs in the fuel pump still gets no power that you can read when testing? Ignition key turned on of course.


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## ziggydub628 (Feb 10, 2010)

correct.


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## WaterWheels (Aug 14, 2005)

With the ignition on or off, you should have a reading of battery power (12v if you will) at the one relay socket marked 30 or with a + (some only have numbers which don't indicate the circuit). In any case of the two large sockets one, left I believe, should have constant battery power. If you do not then everything after that, relay, pump, wiring is un-important right now. Confirm that there is always battery power there.


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## ziggydub628 (Feb 10, 2010)

i have power at the relay, but not the plug, even with a brand new relay, or with terminals bridged, this leads me to believe the problem may be in the wiring. If so, where would be the best place to start?


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## ziggydub628 (Feb 10, 2010)

the point with power is the bottom socket, it is a narrower socket


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## WaterWheels (Aug 14, 2005)

For your car, 85' if that's the one you're working on, it should not be one of the bottom ones. There are two large sockets, one vertical and one horizontal which the large pins od the relay plug into. One is battery power, the left as you look at it I believe, and the other is where the power exits the relay going to the pumps. The bottom I believe is the one which should only be hot with the ignition on. If you can read the numbers on the relay where the pins are and post what number you are talking about it would help. This also needs some explaining:


> i have power at the relay, but not the plug,


I'm sure everything will fall into place and things can be worked out here if things are explained clear.


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## ziggydub628 (Feb 10, 2010)

This is the 85 that I am working on. At no time do I have power to the left, horizontal plug (30). The only place that I ever get power is the bottom skinnier, horizontal socket (86) with the ignition on.


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## ziggydub628 (Feb 10, 2010)

Additionally, there is no power to my fuel pump fuse. What is the route of power from the battery to fuse/relay? Are there more relays that the power goes through first, or does the power come directly from the battery?


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## ziggydub628 (Feb 10, 2010)

anyone able to help?


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## WaterWheels (Aug 14, 2005)

OK, if seems you have discovered the root of the problem. I do not have any material which shows the exact path from the battery to the pump relay. Some US models have fuseable links comming off the battery, I don't know if your's does and if it does if one provides power to the pump. You are going to have to look behind the relay panel and try to trace the flow that way. Some have thick red jumper cables in the rear of the panel to distribute battery power, maybe one fell off? Could also be the relay panel is bad. Just can't say from here, sorry.


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## ziggydub628 (Feb 10, 2010)

I have also found that I have intermittent to the fuse for the pump. What could cause this? Loose wire somewhere I would assume? And further how do I remove the relay board? It would be easier to trace wires if I could move this.


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## ziggydub628 (Feb 10, 2010)

My book is a little unclear, but it seems that the power from the fuse is supposed to come off of the load reduction relay. Assuming this is correct, I tested for power in that relay's location with the ignition off and have no power to any socket. However, when the power is on, there is power to the bottom socket. My assumption is that there is supposed to be constant power to one socket, just like with the fuel pump relay, is this correct?


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## fluboyaviator (Mar 8, 2007)

*replacing both pumps*

Lookig for the link to the HOW TO with pictures on how to replace the In the tank pump and the outside main fuel pump. Any help would be greatly appreciated (not much of a mechanic) 1989 Cabriolet, automatic.


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