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ECU Code 78 (8) on 3.0 D4D 2003


ginter1234
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Hi all, 

Been trying to find out what exactly could cause this fault code - ‘Fuel Pump System Malfunction (Short)’. Hesitation on accelerating, but only in cold weather & when engine is cold? Changed air & fuel filter. I just got Techstream off eBay, but don’t really know how to use it properly yet. Here is a pic. Could it be the SCV’s I keep reading about or maybe a wiring fault? It’s fine when engine is warm. Thanks in advance for any advice. 

 

81411629-0EB7-4B79-8F3F-CBA92AF8A540.jpeg

Edited by ginter1234
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It's likely going to be one of the following:

Faulty fuel pump
 Faulty fuel pump wiring harness
 Faulty suction control valve ( SCV)
or  Clogged fuel injectors.

I highly doubt it's your fuel pump as you'd probably be having bigger issues overall if it was.
It's not likely your wiring either as it only happens at a specific condition.
I'd run some injector cleaner through it across a couple of tanks of good quality diesel to help rule the injectors out. (suplher when it combines with other metal alloys aids lubrication. Less sulpher less lubrication etc)

If an injector clean up doesn't help I'd strongly be leaning towards replacing the SCV.


 

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Any ideas why it would only do this on cold day’s (near to freezing)? Cheers 

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My guess would be that the cold weather is causing the piston in the SCV to seize up or move alot less freely.

If a batch of good qaulity fuel and injector clean with reddex of something doesn't help. I'd replace the SCV. A new SCV is gonna set you back about £130 / £170 for a geniune Denso one.

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3 minutes ago, JayG said:

My guess would be that the cold weather is causing the piston in the SCV to seize up or move alot less freely until it's up to temp.

Thanks Jay, appreciate the advice. I did try injector cleaner a while back when it did it. It always gets Shell V-Power now and has had for months. It’s just so random when it does it, but does seem to be more frequent now. Thanks again. 👍

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No problems :smile:
In a pinch, the SCV pretty easy to remove.  Just a couple of bolts under the bonnet.
 You could try removing it and giving it a soak in some brake or carb cleaner.

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Just been looking on eBay. Think these are for the KD engine. Will maybe try cleaning the old ones first though, before spending £123! Do you know why 2 are used on this engine? Cheers. 

3978DF88-C039-4705-B0D1-DD06FF591A50.png

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  • 2 years later...

Did you ever get round to sorting this out? Had same code. Changed suction control valves and did have the code come up again. 

When I rev it, I do see black smoke but not a huge amount. Like initially bursts of black smoke then after that ok. From my experience it seems injector or injectors. 

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