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  #41  
Old December 14th, 2013, 02:53 PM
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Originally Posted by rijosho View Post
RoverGauge and Jason to the rescue this morning! We were joking that it took longer to get coffee than it did to get the truck started. Had been having an issue where the truck would prime but the fuel pump would not run, therefore the truck would not start. It'd come so close, but just wouldn't. Had left the truck battery unplugged for a few days after the first time it happened to try to reset the ECU. Still wouldn't start though. Today, Jason came with the RoverGauge and manually ran the fuel pump and she started right up! Relays were functional, but ECU wasn't sending signal to them I believe.
Witchcraft!

I have a big suspicion that this is the root cause of the 'failing' fuel pump relays we see here a lot.

Based on my own experience I strongly suspect that after a nostart or stall and nostart for some reason the ECU gets in a bad place. I'm guessing it's designed to protect the engine from damage. But basically it won't run the main fuel pump relay. It's a 2 second fix with a rover gauge. I'm also theorizing another method which jumps the relay and forces the fuel pump on.

I suspect once it's running it would get the ECU back into a normal state.
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  #42  
Old December 14th, 2013, 03:09 PM
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Originally Posted by leastonce View Post
Witchcraft!

I have a big suspicion that this is the root cause of the 'failing' fuel pump relays we see here a lot.

Based on my own experience I strongly suspect that after a nostart or stall and nostart for some reason the ECU gets in a bad place. I'm guessing it's designed to protect the engine from damage. But basically it won't run the main fuel pump relay. It's a 2 second fix with a rover gauge. I'm also theorizing another method which jumps the relay and forces the fuel pump on.

I suspect once it's running it would get the ECU back into a normal state.
So can you just "reset" the ECU using the Rovergauge?
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  #43  
Old December 14th, 2013, 03:53 PM
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You can clear fault codes and do a couple of other things like force the fuel pump on. The ECU is an embedded system that has limited logic. I guess you could call it a reset ... Clearly though some information is preserved in the memory ... Like fault codes and this appears to influence behavior of the fuel pump controls.
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  #44  
Old December 14th, 2013, 04:06 PM
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Odd. Try another ECU but I'd sooner suspect that something isn't giving it a signal to tell it that the pump should run before the ECU going bad.
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  #45  
Old December 14th, 2013, 04:21 PM
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Odd. Try another ECU but I'd sooner suspect that something isn't giving it a signal to tell it that the pump should run before the ECU going bad.
I'd be inclined to agree that some signal wasnt getting to the ECU to tell it to turn the fuel pump on ... this is coil signal ... but it's definitely getting there as once you kick the fuel pump on via the rover gauge it all works again.

Given the number of fuel pump relay 'failures' i would think this is a pretty common state.

Josh's truck and mine are functioning perfectly well now. Mine hasn't done this in over a year.
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  #46  
Old December 14th, 2013, 06:09 PM
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It can be a situation where a fuel injector is leaking. It can bleed off all the fuel in the fuel rail and siphon some of the fuel out of the fuel lines. Since the fuel pump only runs a few seconds before turning the key to start it will not pressure up the fuel system enough to run. The fuel pump will not be prompted to stay running until the engine fires up and has a constant dwell reading coming from the coil.

You could test this by turning the key off and on a number of times to bring the fuel pressure and volume back to the fuel rail. You have to wait a certain time between key on sequences to allow the ECU to reset, after you hear the main system relay click off you can prompt the key again to pressure the fuel pump a few seconds again.

The problem with a leaking fuel injector is it damages the cylinder it is leaking into over time. So it would need to be identified and replaced.


Quote:
Originally Posted by rijosho View Post
RoverGauge and Jason to the rescue this morning! We were joking that it took longer to get coffee than it did to get the truck started. Had been having an issue where the truck would prime but the fuel pump would not run, therefore the truck would not start. It'd come so close, but just wouldn't. Had left the truck battery unplugged for a few days after the first time it happened to try to reset the ECU. Still wouldn't start though.

Today, Jason came with the RoverGauge and manually ran the fuel pump and she started right up! Relays were functional, but ECU wasn't sending signal to them I believe.
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  #47  
Old November 14th, 2014, 05:36 PM
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Charles Galpin
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Anyone with RoverGauge and a 4.2 v8? I have a guy with tune resistor issues asking for a fuel map to compare to.
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  #48  
Old November 14th, 2014, 09:53 PM
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Is this an aftermarket or European spec chip? The nas 4.2 bin I've examined had the tune resistor disabled and all of the other maps were the same as a 3.9
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  #49  
Old November 15th, 2014, 08:45 PM
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Charles Galpin
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Good question. All I know is its a 1993 Range Rover Classic LSE 4.2 and it's in Hungary, so maybe euro spec?
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  #50  
Old November 17th, 2014, 01:54 PM
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http://www.flemcodesign.com/14cux/14cuxbin.zip

3361 is the NAS 4.2 for a 95. Its not the latest operation pride chip, but its what it would have had from the show room floor.
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  #51  
Old November 17th, 2014, 05:29 PM
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Charles Galpin
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Sweet, thanks Robert. I'll let him know.
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