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Premium Member
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11,585 Posts
Discussion Starter #1
I went to start the car earlier to go visit Karen and Adam and it started then promptly died.

No fuel pump 'whirr' when the key is turned.

I checked the fuse and I tested the resistance and both were fine so tried a direct 12v feed and it worked; car started.

Checked the power to the coil and switch sides of the relay, which should come directly from the fuse I tested earlier....5v :zoinks: So I tested the power at the fuse...12v :-\
I've taken a feed from the air-con (which I don't have) relay position and connected it to the output side of the switch side of the relay...so it's going directly to the pump.

Only problem is that the pump doesn't cycle now, it's on constantly. BUT it's got me going for now.

So, anybody got a clue why I only have 5v at the relay ?????
 

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CH0DEmobile
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3,202 Posts
EDIT: I need to read better, it's early :p You relay probably has some burned/pitted contacts on the switching side. What's the voltage drop across the switching side? Do you just have 5v going in, or 5v coming out?
 

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drunken master
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10,091 Posts
so you have 5v to relay or 5volts out.
the ecm turns the fuel pump on and off. if you use a seperate power you cn wire nother relay useing the ecm signal to trigger the relay.
also pull you fuse out i hve seen corrosion of one pece of fuse break at contact so fuse will test good on both side's
 

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CH0DEmobile
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3,202 Posts
Hrm, after waking up a bit and reading mark's post a bit more carefully, it sounds like he's got 5v going into the relay. Since he was able to get full power by going off the AC relay plug, I'd say the fuse box may be at fault, as carlos suggested. Install the voltmeter and wiggle the wires underneath the box, see if that changes the readings any. Also, try checking the resistance between the connection in the box and a point in the wire going into it. (If that makes sense)
 

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Premium Member
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Discussion Starter #6
I have 12v at the fuel pump fuse but only 5v at the relay, the same wire feeds one side of the coil in the relay and the common contact. The other coil contact is switched to ground by the ECU. OS there's not enough voltage to trigger the relay and if there was then the pump would only be getting 5v.

I've just bridged the 12v from the AC relay connector across to where the output connector of the fuel pump relay would be if the relay was actually fitted.

Why do these things happen at the worst of times. I wanted to get to the hospital earlier.


I've checked the wiring diagrams and nothing else in on the supply side so it's got to be a dodgy connection somewhere. The only other thing on the output side is the air regulator.

It was working fine on Friday when I drove about 80 miles all over the place. :evil:
 

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Premium Member
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Discussion Starter #8
Well I have to find the wires and find the loose/corroded connection. That's the fun part; I hate wiring...
 

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drunken master
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10,091 Posts
so mark all wires testing relay from back of rely while connected exept out put hav 5volts? mabe you can put up the digram and let me know what you got and were with relay conncted.
if you wnt to run new wire's to relay so itworks right. This will be a very easy fix.
shit but remembering to test from the back the relay box has to be dismanteled
 

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Premium Member
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Discussion Starter #11
I know 5v won't operate the pump, it won't even trigger the relay I bet.

No I haven't tested from the back with relay connected because as you say, I have to dismantle the relay box and I needed to get to the hospital :-\

I think I'll be running a new wire from the fuse to the relay connections.

Some diagrams... http://img155.echo.cx/img155/9194/ecuwiring9zg.jpg
http://img232.echo.cx/img232/5769/powerrouting3vr.jpg

I have 12v at the 15A fuse shown in the second diagram with the BRown wire. But only 5v on the BRown wire going to relay 40.

Here's the temp fix, a bit of tig rod bent to supply 12v to the output terminal. :p
 

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Premium Member
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Discussion Starter #14
Nope, car has been of the road for over a year. It still has that bit of stainless rod there connecting the AC relay plug to the fuel pump relay plug.

It needs a length of wire running from the fusebox in the car to the relay connector.
 

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Questioning Answers
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6,853 Posts
my car aint starting, i get no power off the fuel pump connector (2 wire connector, black wire, & black wire with red stripe) i do get some readings on the 3 wire connector (but i dont think thats the power connector) i get 12v @ the fuse in the cabin.....

i tried to see what i was getting @ the relay connector but i didnt get anything of any of the terminals in there (FSM says to check 2 & 3, & a ground , i used the strut tower ground location)....i pulled both fuel lines, (the one going into the FPR, & the one going into the raill from the fuel filter & i get no fule pumping....


i even tried runnning a wire from the fuse box to the pump directly & nothing.....


right now i have given up....i dont know what esle to do.....

how do you check for voltage @ the relay location? (just put the black lead from my multi meter on a ground location & the red lead from the multi meter to one of the relay socket locations right??? ) i ddi that but didnt get any reading @ all
 

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Premium Member
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Discussion Starter #18
Yea you just need an earth point then check the relay socket. As you can see form my pic, there should be a 12v supply on the bottom left. Also 12v to the top right. Both are from the same supply wire from the fusebox. The bottom right goes out to the pump. Top left goes to the ECU which switches the earth to trigger the relay coil so connecting the bottom left 12v through to the output to the pump.

I don't know why you are finding no power there at all. Maybe a dodgy wire between there and the fuse ??

Do you have a good earth to the pump connector ?? Try running a couple of wires, one for a ground and one for 12v and see if the pump works. Be careful with connectors near the fuel tank, you don't want stray sparks [:)]
 

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Questioning Answers
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i have a buddy comng over today with a power probe.....so hoperfully we get to th bottom of thisgod amn connundrum!!!
 
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