Engine Cutting Out

[mowflow 67]

Standard grade maths works it out as 333ml in 30 seconds. Not convinced I've got that right.

[welshpug 1,661]

I believe they are meant to be rated at 180 lph at 3 bar, so that'll be 3 litres a minute!

[mowflow 67]

Ta. Complete maths failure from me there then.

 

It's flowing nowhere near that.

[Thijs_Rallye 87 4 Cars]

You can wire up the pump directly to a 12 V source to eliminate wiring issues.

 

@Dobboy, 12 V at the connector doesn't mean much if the pump isn't running, that is what I mean by loading it. The pump should have resistance in the line and pressure regulator, hence increasing the power draw. If you have a bad earth the voltage will be divided over the earth connection and the pump as soon as the current goes up due to the load.

[mowflow 67]

Okay, I understood almost none of what you just posted Thijs.

 

Here's the results of the latest tests.

 

1. Connector off the loom disconnected from the pump shows 12v with ignition on (I understand this proves nothing)

 

2. With the pump plugged in, ignition on and the pump running I get 6v on both the loom and the pump side.

 

3. Sticking 2 wires off a battery straight into the pump the pump sounded like it had a new lease of life and fuel flowed like a bugger

 

So is this proof of a bad earth? Any more tests I should do?

 

Also note after doing test 3 i removed the earth block behind the rear light in the boot, gave it a good clean up and put it back together. This made no difference.

 

Is the easiest fix to run a new earth wire? If so, where is the best place to run it?

 

Edit to add. I'd appreciate if answers were child friendly as electricals isn't my thing.

Edited July 7, 2017 by mowflow

[Tom Fenton 1,542]

Your tests show there is high resistance somewhere in the circuit, but it's not pinpointing where. Could be earth -yes, but could also be on the positive feed via the relay.

 

Couple of tests- run a new earth from the pump to a good metal point on the car, door striker is a good one or a seatbelt bolt. Try running pump from the key and see if it now responds as it did from the direct battery. If so it's a bad earth, the wiring usually isn't bad so have a good look at the earthing point inside the boot nearside of the car.

 

Next test, put the wiring back as intended. Locate the fuel pump relay under the dash. Unplug the relay. With a short length of thick wire bridge the two heavy white wires on the plug side. If my memory is correct this should feed 12v straight to the pump. If it then runs right then it could be high resistance inside your fuel pump relay.

[dobboy 231 2 Cars]

(non mechanics explanation)

 

The voltage drop you see "on load" shows you have a dodgy connection somewhere, not necessarily on the earth wire; could be the supply wire or anything in between.

 

It's (Volt drop) = I²R

 

These are losses you have, ( due to a higher resistance than what should be there). Basically the increase in resistance has increased the (designed) volt drop.

 

But now you know it's wiring related and should be easy to narrow down.

 

Start by looking at the ends of the wiring, look for a dodgy connection(s) and clean everything.

 

Thijis picked me up wrong ^, and said what i was trying to say on my previous post.

 

no load (open circuit) = no current flowing = no "I" flowing, therefore no "I" to be squared for the Vdrop equation, therefore no volt drop.... (losses). Thats why you have 12V on the disconnected plug.

 

 

So in your case, you have an increased resistance ® somewhere, but it could be from feed to pump, or pump to earth. It could be a dirty connection, a really thin bit of wiring jambed (heavily kinked/compressed); anything that would stop current flowing.

 

(treat like water flowing and you'll find it)

[mowflow 67]

Your tests show there is high resistance somewhere in the circuit, but it's not pinpointing where. Could be earth -yes, but could also be on the positive feed via the relay.

 

Couple of tests- run a new earth from the pump to a good metal point on the car, door striker is a good one or a seatbelt bolt. Try running pump from the key and see if it now responds as it did from the direct battery. If so it's a bad earth, the wiring usually isn't bad so have a good look at the earthing point inside the boot nearside of the car.

 

Next test, put the wiring back as intended. Locate the fuel pump relay under the dash. Unplug the relay. With a short length of thick wire bridge the two heavy white wires on the plug side. If my memory is correct this should feed 12v straight to the pump. If it then runs right then it could be high resistance inside your fuel pump relay.

With this second test do you bridge the white wires to each other?

 

I read somewhere about bridging both whites to the thick brown wire.

[mowflow 67]

Ran an earth to the door striker and pump ran weak.

 

Bridged the 2 white wires at the tachy relay supplying constant live to the pump and still ran weak.

 

Put the relay back in and ran a wire from the thick brown wire to the pump. Ran like a champ.

 

The interior is out the car so I can see there's no kinck or pinch in the wire running to the pump. I need to figure where it goes at the dash end and check the ends are good. I guess I start by stripping back the ends.

 

Thanks all for your help so far. It feels like I'm finally getting somewhere.

[welshpug 1,661]

the chunky brown wire is a permament live in the engine loom and plugs into the shunt box from memory.

[welshpug 1,661]

from the relay it joins the dash loom at the brown plug/s into the fusebox and out to the pump.

[mowflow 67]

Well whatever is happening to the electro trickery it's happening somewhere after that relay.

 

The live on the pump is white so i take it one of the white wires from that relay plug is the live to the pump. Probably via the fuse box.

 

I did try to make sense of the Haynes wiring diagram, but couldn't.

Edited July 8, 2017 by mowflow

[Tom Fenton 1,542]

It could still be the relay at fault. At the plug with the relay out bridge from the brown to the white with a thick jumper lead. I think one white is pump one is ecu, just do one at a time to see which is the pump. If it then runs 100% you have proved the wiring is ok and the relay is bad.

[EvilElmo 0]

I had the very same issues with my '87 GTi, took me about a month to figure out the fuel pressure loss was coming from a leaking fuel pump reducer pipe, that's the bit of rubber joining the pump to the housing.

I got a replacement from a guy on this forum, worked a treat.

 

(how is this my first post??)

Edited July 9, 2017 by EvilElmo

[mowflow 67]

Still weak with the one white wire bridged. It's the outside white one that appears to be the pump.

 

I think I've found the problem.

 

 

The white wire with the blue bodged bit goes to the pump. The thin blue and white wires look like they go to the fuel level sender. The yellow wire is about 15cm and goes to this...

 

 

The thick white wire at the other end of this runs off through the bulkhead as far as I can tell.

 

If I connect a live to the white wire at the yellow block the pump is weak.

 

If I connect a live to the thick white wire that goes into the black plug I get full pump power.

 

What should this lot look like?

Edited July 9, 2017 by mowflow

[welshpug 1,661]

looks about right but I would get rid of the blue crimp connector, thats likely the cause.

[mowflow 67]

Where does the power come from here? By that I mean the yellow wire (which seems like the live feed) doesn't actually connect to the white pump feed wire? The 2 are in the same end and don't visibly connect.

 

Is it effectively wired in sequence after the level sender?

 

The reason I ask is because if I jab a direct live to the pump via the yellow wire I get full power but if I do the same on the white wire (bypassing the dodgy blue bit) I get a weak pump.

[mowflow 67]

This is going to drive me insane.

 

I read the Haynes wiring diagram was for an early phase 1 so it only works as a rough guide.

 

It appears the blue and white wire aren't the fuel sender. I traced them to the boot lock (wires 200 & 201). Why would Peugeot wire the boot lock in a loop with the fuel pump??

 

I think I've gone wrong with the plugs somewhere.

Edited July 10, 2017 by mowflow

[EvilElmo 0]

CHECK YOUR FUEL PUMP FITTINGS!

[EvilElmo 0]

SORRY FOR YELLING! I'M A VERY LONG WAY AWAY!

[mowflow 67]

Hahaha U WOT M9?

 

I'm pulling all the plugs in the fuse box/under the dash. Surely not even the French would wire the fuel pump to the boot lock?? I could see the Italians doing something like that but not the French.

 

Just trying to find an image with that plug to see where it goes

[EvilElmo 0]

Even if I'm wrong, (ha!) it's only 15 of your "quids" or something...

[EvilElmo 0]

Did you ever figure out what the problem was?