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PostPosted: Sat Aug 20, 2016 5:00 pm 
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Folks,
I've just come back in from changing the fuel pump in my Jeep Cheroke 4.0. I did the same job two years ago and fitted a Denso pump. This time I've fitted Bosch.
I see to be getting through them pretty fast. Bearing in mind that the fuel tank is clean (and it's only three years old) I'm starting to wonder if running the fuel pump constantly against closed fuel injectors is causing a problem.

What do you guys reckon?


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PostPosted: Sat Aug 20, 2016 9:18 pm 
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Is there any sort of return from the fuel injectors to the tank?


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PostPosted: Sun Aug 21, 2016 10:20 am 
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Nope, just a one way line from the pump to the fuel rail from what I can see.
edit: some googling round the Jeep forums seems to confirm that this fuel system is just one way.


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PostPosted: Sun Aug 21, 2016 5:51 pm 
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It does sound like it could be asking for trouble to me - its not unknown to fit a fuel return on some cars due to them altering the injection timing relative to fuel pressure. Whilst you could cut off the pump the risk is when it needs to switch you won't have enough pressure there to keep going until the pumps got back to pressure.

Is there any way of viewing the fuel pressure? or confirming that the pump is definitely running all the time if you can get to it?


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PostPosted: Sun Aug 21, 2016 7:14 pm 
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The return is built into the pump assembly, it's part of the pressure regulator on the top.


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PostPosted: Sun Aug 21, 2016 8:35 pm 
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Pumps burning out on Jeeps due to lack of return or pump cutout isn't a common issue...

Far more common that the pump loom or loom connectors get corroded, perhaps particularly if an aftermarket tank is fitted and wiring has been extended, or a secondary cutout relay (when running on LPG) goes wrong.

Simon

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PostPosted: Mon Aug 22, 2016 1:26 pm 
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It probably has an easier life than a normal feed/return line setup, as it doesn't have to pump fuel right up to a front-mounted regulator, it just dumps it back into the tank. The Tinleytech setup doesn't need a secondary loom as far as I could see - looks very "Chrysler rubbish wiring" where it hooks up!
I've read on a couple of the Jeep forums that virtually all the fuel pumps you get now are outsourced to China these days, no matter the brand - my new one certainly felt a hell of a lot cheaper than the original.


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PostPosted: Wed Aug 24, 2016 7:34 pm 
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Well, it's up and running again now with a Bosch module :) Yep, it was the only option I could find that wasn't explicitly Chinese. It even came with a two year warranty.
The downside is the price and the fact that I could only find one in the USA so I had to wait a week for shipping.

If the pump is just dumping fuel back into the tank from the regulator on the top then I guess that's the return line. It'll just be straining the petrol again, and again, and again..... I'm still curious as to whether the lifetime of the pump could be extended by switching it off once you change over to LPG.

Simon, you're right that the wiring is pretty low quality but I was getting 12V where I was supposed to so I went for the new pump.


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