Fuel filter: improved response?

surj · Post by **surj** » Mon Dec 15, 2008 10:48 am

Hi All,

Other than helping to ensure that any dirt particles in my fuel are kept out of the injectors/engine, are there any other reasons why regular fuel filter replacement is recommended?
i.e. will it improve/maintain good throttle response/acceleration?

The reason I ask is that I'm not sure when it was last changed on my car and it seems a tad slugish compared to when I bought it (few months ago)

Checking the maintainence paperwork doesn't give any clues as to when it was last replaced.

Noid · Post by **Noid** » Mon Dec 15, 2008 11:49 am

Yeah, obviously if there are bits in the fuel then it will affect performance in some way, though generally i find that bad performance is more of an ignition issue.

Depends really on what sort of car it is, is it diesel or petrol, turbo or non turbo. What type of engine is it? Conventional or rotary (Wankel)?

Need more info.

surj · Post by **surj** » Mon Dec 15, 2008 11:56 am

Sorry for the lack of info. It's a conventional turbodiesel engine in a mitsubishi carisma which I'm realiably told is a renault 1.9l (f9q) engine.

Noid · Post by **Noid** » Mon Dec 15, 2008 12:09 pm

Yeah, engine is the same. Bad fueling can affect the performance on a diesel but the best way to fix it would be trial and error more than anything as it could be a number of things, even the turbo losing pressure.

Does it make any hissing sounds or any rattling or is everything nice and sounding how it should?

surj · Post by **surj** » Mon Dec 15, 2008 12:13 pm

Everything sounds a-ok so I've not considered that it could be anything turbo-related.

Noid · Post by **Noid** » Mon Dec 15, 2008 12:23 pm

It could even be that you are used to the car now and that makes it feel slugish, mine is 300bhp and although i was terrified of it when i got it, it's boring in comparison now.

Regular servicing keeps a car feeling good so maybe a full service is called for? Not something you can't do yourself, just get the parts and do it in stages.

surj · Post by **surj** » Mon Dec 15, 2008 12:40 pm

I've done the "rest" of the service myself but I never replaced the fuel filter. To be honest, it could just be a you described, that I'm imagining that it's slower now....

Noid · Post by **Noid** » Mon Dec 15, 2008 12:42 pm

If that's the only thing left to do then get it done. (Just make sure it's full of fuel when you replace it of you will have a problem.)
What's the fuel consumption like in comparison to before and have you changed the air filter?

surj · Post by **surj** » Mon Dec 15, 2008 12:57 pm

I've changed the air filter at the same time as the rest of the service and the consumption is steady at circa 49-50 mpg, as it has always been.

Hitch · Post by **Hitch** » Mon Dec 15, 2008 1:35 pm

For the sake of less than £10 its worth changing, its probably not even a 10 minuite job for a diy mechanic.
Just make sure you seat the replacement o-rings in place properly.
Fill the bowl/housing with diesel will make it a bit easier.

If youve got a hand primer pump squeeze that until it gets hard, that pumps fuel back to where it should be. The rest is most likely self bleeding, just crank it over untill it fires up. May take a number of times.
Do it when the engines warm will save a bit of battery power incase it doesnt bleed that easily.

surj · Post by **surj** » Mon Dec 15, 2008 2:17 pm

Yep, the car has a primer under the bonnet so that would be my method of bleeding the air from the line.

Raf · Post by **Raf** » Mon Dec 15, 2008 3:13 pm

tad sluggish; what do you mean.... alot slower? lack of torque up hills? does the car smoke more than before? you say economy is the same; is this off the trip computer or brim to brim calcs? if computer have you re-set it?

start with a fuel filter as suggested; its more important on diesels than petrols as diesel is a "dirty" fuel.

also clean EGR valve.... this maybe stuck and not closing fully allowing exhaust gases to leak into engine (if it has one; it should if its fairly newish). this is a serviceable item.

you could disconnect your MAF/MAP sensor to see if there is any change; if no change (and hence car running on default map) then you need a new one.

do the cheap and cheerful things first; if no go then report back for more info but basically sluggish on a turbo diesel can be many things (turbo, collpased cats, variable vane actuater stuck, boost controller clogged, low fuel pressure, EGR controller, vaccuum leak etc etc etc). if the above checks dont fix anything then the best thing is for you to get the error codes read (as apposed to changing stuff in a hit & miss sort of fashion).

..... on another thought is your throttle fly by wire or cable?

surj · Post by **surj** » Mon Dec 15, 2008 3:31 pm

Wow, I wasn't expecting a detailed response as that, lol.

I must say that the lack of throttle response isn't that drastic that I feel the need to throw anything more than £30 or so at looking into. As I've said, economy wise nothing has changed hence I'm not that bothered about it.

I'll look into changing the fuel filter as I've also been told that it coul be clogged due to diesel being what it is.

Raf · Post by **Raf** » Mon Dec 15, 2008 5:04 pm

alright sorry i thought since you asked on the tinterweb it must be something troubling you..... in that case chuck some millers diesel treatment and bobs your uncle

dewaltdisney · Post by **dewaltdisney** » Mon Dec 15, 2008 7:25 pm

It could be the diesel bug. A mould like sludge can get sucked through and cause fuel starvation. If you have a small amount of water in the tank, which can accumulate through condensation, a micro organism can develop in the diesel water interface. This 'sludge' can get sucked through and trapped by the filter and there is power loss. I had this on my tractor and it actually stopped the motor. I had to drain the tank down and clean it out and swap the filter to get it going again. I now make sure the tank is full up with diesel over winter to sop condensation forming.

So, if the filter has black mould like crap in it you may need to flush the tank.

DWD