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3.9 V8-no power to the fuel pump?


reggie
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Hi guys,

Hopefully somebody might have some useful advise on a long term problem I've had with the Rangie.

Some time ago I got it a little wet inside :unsure: & since then the fuel system hasn't been working & has only been running on LPG.

The other day a friend & me tried again to find out the source of the problem once & for all but were left a little defeated but we haven't gave up yet.

We took out the drivers seat for access & got in with the multi meter to try & find out whats going on, we had 12 volts going to the ECU, swapped over the relays & fuses under the drivers seat & tried another ECU but it still wouldn't start on petrol. We tested the fuel pump & its not getting power.

Is there some relays or fuses that we might not know about that control the fuel system, I know there are lots under the dash but where do you start if you don't know whats what?

It has got to be a relay or fuse I think as it was running fine until I submerged it in water then the petrol system just stopped working :o

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As you will probably find if you search or go through the comprehensive faulting guide in the tech archive (hint hint) the ECU controls the fuel pump and will not switch it on until it sees some pulses from the coil -ve terminal (and/or some airflow from the AFM, system dependant) so you may need to widen your search.

Best advice is to work methodically through the faulting guide in the tech archive, don't skip any steps, and post up if you hit a strange result.

Quick test is to jumper across the relay socket pins and see if volts get from the battery to the pump.

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You have not said what year this is.

You say you have replaced the relays under the seat but one of them is not a relay it is a diode pack. If that has been replaced with a relay then the system will not work even if that was not the original fault.

Was the ECU submerged?

Steve

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You have not said what year this is.

You say you have replaced the relays under the seat but one of them is not a relay it is a diode pack. If that has been replaced with a relay then the system will not work even if that was not the original fault.

Was the ECU submerged?

Steve

Its a 93 & yes the ECU was submerged for a while. The relays that I changed were straight out of a working rangie like for like so I did use the right ones.

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Wiring between the seats is notorious for going crusty. Basically ECU and fuel pump relay live under the drivers seat and the intertia cut off under the passenger seat. There's a white cable there and back, which has a connector in it which wasn't up to the job 15+ years ago, never mind now.

Worth a check :ph34r:

Fuel pump should run for a few seconds on ignition power up, then won't run again until the ECU sees tach pulses like Hybrid From Hell describes.

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I had the ECU lid of the very next day after the water incident to dry it out & it looked mint to be honest. It even looked like it had some type of protective coating on the board its self. Anyway to avoid not knowing if it worked or not I swapped it over with an ECU from a running rangie parked next to it. The results were that the running rangie still ran fine with my previously submerged ECU in it.

I also checked the ECU plug the other day again & no signs of corrosion or anything out of the ordinary, although one pin did look a little set back.

I haven't looked at any wiring between the seats yet as I wasn't aware they was any, thought the wiring was just under each seat. On thinking about the issue many times, I can't see it being a corrosion issue though as it was running fine before the water incident & as soon as I got it out of the ford the petrol system had packed up, indicating a fault at the that time as a result of the water. If the problem happened sometime after you could suspect corrosion as the cause over time.

Basically the issue happened as soon as everything got wet, It was bloody deep & the dizzy got wet causing it to splutter to a halt & the the water filled up to the seats. As soon as I got it out it wouldn't run on petrol anymore & been that way since :(

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Might be worth putting a fan heater under both seats in case there is some water still causing a short circuit in a plug etc.

i'm assuming you have already checked all fuses - dash panel and i believe there are some under the passenger seat and a couple under the driver's seat.

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I haven't looked at any wiring between the seats yet as I wasn't aware they was any

Neither was I........... Until one day it just wouldn't start or run on petrol. :blink:

Fine on LPG. I could rule out the tach pulse from the dizzy as my LPG system needs it too, like you I found no power to the fuel pump, but hte pump ran fine when fed 12v off the tow electrics. Intertia switch, was fine, power was at the output side of the relay, so in desperation I started following the wires..... My problem was all down to one pxy connector that was literally powdery white. It had been dampe under the carpets for years. Chopped it out and applied old fashioned solder and it's been fine ever since.

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Neither was I........... Until one day it just wouldn't start or run on petrol. :blink:

Fine on LPG. I could rule out the tach pulse from the dizzy as my LPG system needs it too, like you I found no power to the fuel pump, but hte pump ran fine when fed 12v off the tow electrics. Intertia switch, was fine, power was at the output side of the relay, so in desperation I started following the wires..... My problem was all down to one pxy connector that was literally powdery white. It had been dampe under the carpets for years. Chopped it out and applied old fashioned solder and it's been fine ever since.

I'll be checking that out then as you never know, be good if thats all it was but some how I'm not feeling that lucky :rolleyes:

Be good to change it or solder it anyway if its a problem spot.

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