Diesel fuel filter?

[munz]

Hello all, capable newbie, but new to the land of diesel. I have a 4JG2 I think, 3.1DT, badge engineered Isuzu Mu (Honda Jazz) '94. I have had this for a few months now and have noticed considerable performance differences at random times. It doesn't seem to follow any logical reasoning either... crisp or warm air, station I get my diesel from, time of the day, or a warm/cold engine etc!? Often it feels as though it has retarded timing if it had spark Average upto 3000rpm, and poor after that... Bit of a slug really. Other times, what a gem! It pulls like a school boy! The thing that has me is the randomness of it. If you like, please send me your input, however to eliminate one option I am going to change the fuel filter as I think it is a good place to start. I just need to know where to find this one, and how to avoid air in the system and/or learn how to bleed the air from the fuel system. Any help greatly appreciated.

Jurgen.

[geeves]

About half way down the left guard there is a 4 inch square thing with a 1 inch round thing on top and a tin can underneath. The tin can is the filter and the round bit is the priming pump.There is a rubber hose that goes to the fuel pump and 2 others. Under the filter there is an assembly with a small hose and 2 wires. Disconect this first. In some cases its easier to remove the complete assemby then remove this bit than doing it in place. Remember about a liter of diesel will splash about your feet when you remove this part which is the water seperator. Then you can unscew the filter and replace. Its always a good idea to wipe the rubber seal with a little clean oil so it seals better. Then refit the water seperator and if you removed the whole assembly refit this now. The remove the rubber hose to the pump (only one that goes to the engine) and push down on the round bit(priming pump) a dozen or so times till fuel appears at the end of this hose Refit the hose Done Easy
Anouther thing worth trying is a bottle of injector cleaner in the next tank of fuel. Also when its playing up stop and make sure you dont have any binding breaks. This is a common problem on most 4wds

[munz]

Thank you so much, I will go have a look at doing this after I have had my first or second coffee And... I never would have thought of binding brakes, it really doesn't feel like that, however it's nice to have someone keep your mind fresh on unique (or not so much as you say) ideas to rectify a problem.

I already have the injector cleaner, but thought it may have been a waste without the filter replaced so haven't used it. Will pop it in after the filter replacement, so let ya know how I go... You do make it sound easy, so here's hoping

J

[geeves]

Anouther thought is diesel bug. If you find long green and black stringy stuff in the filter consult a local diesel mechanic on what to do before refitting the filter. None of the things are hard but they are messy and time consuming

[munz]

Thanks again... Fuel filter mission was a success! Quite easy actually. Everything as described except for the priming of the filter took approx 7892 pumps to get the diesel back up through it... Prob because I didn't tip any diesel into the new filter to semi prime it like you would an oil filter. Truck/engine seems noticeably smoother, however I don't believe it has improved the sporadic power situation I initially was trying to achieve by doing this.

Next idea... Can a turbo give varied performance? Because the whine sounds different occasionally also... Should a turbo whine?

J.

[geeves]

Does it make a whistle for 3 - 5 seconds when you switch off?

[adam]

Just on priming the new filter --> I usually unbolt the old one and turn it upside down with the two rubber hoses still connected.

From this angle you can undo the bottom plastic nut without spilling any diesel --> you can then attach the plastic nut to the new filter and with it up right, tip all the diesel in the old filter into the new one.

Then I push the pump thing for a bit to get all the diesel out of the old one into the new one.

Undo the pipes, remove the pump from the old filter and do it all back together.

Usually only takes 5 pumps max to be fully primed again.

[munz]

Turbo doesn't whistle when I turn it off. Has a distinct whistle during operation, sometimes sounds like there is a cop behind me as it sounds like a faint siren muffled by the wound up windows. There is a spot around mid range, with the turbo just spooled ready to go but no or v. slight load (no boost), playing with the gas pedal slightly and holding it in the right place will almost produce a harmonic sound from the turbo. Under normal driving conditions this sound is only heard whilst passing that part of the rev range, and not always is this 'harmonic' audible... Maybe once every 100-200kms Does this mean it is becoming worn? Could this affect my performance as stated if that WAS the case?

PS. Adam, yes I have now learned oh wise one... After a little messy change of fuel filter, hindsight has yet again proved to be a wonderful science LOL.

[munz]

Oh and I recently did my crank belt, not A/C but have tightened them all possibly, only possibly, too tight. Could this explain my erratic power behaviors? Although, I have seemed to note since the fuel filter change that it IS more consistent, but on the lower power part of it's erratic behavior. PS. It is DEFINITIVELY smoother than before the fuel filter change... Weird but cool. Just a thought on the belts thing, I don't think they are too tight, but if they were, could it also be a factor to consider?

[geeves]

By crank belt do you mean the normal fan/alternator belts or the timing belt thats inside the cover. If its the timing belt double check the timing marks. There are 3 10mm bolt holes that you are meant to lock the pulleys to when changing this one and one tooth out can do very bad things

[munz]

No my apologies, the drive belt/fan belt is the one I changed... External. Basically removed A/C Belts, replaced drive belt, placed back original A/C belts and tightened them all...

[geeves]

whistle might be the alternator belt they are nearly impossible to tighten correctly

[munz]

No. The whistle is most certainly the turbo. Does no one here really get an audible turbo sound under operation of it?

After I figured out Isuzu's incredibly complex yet brilliant system... When you know how the mechanisms work for tightening it Mine seemed to go really well. There has been the odd water dip which has actually proved a quick slip from it though so I should keep an eye on that.

I might just start a poll on that whistle question actually... It has been a question in my head for a long time, and not just with this truck.

[geeves]

turbos always make some noise. They cant help it when the tips of the blades are hitting way in excess of the speed of sound while red hot. A little noise is normal but if you can hear it clearly when the bonnets closed it may be a problem. Most common turbo noise is surface cracks in the housing makeing a percussion noise as the blades go past. This is a similar type noise to a helecopter but so fast it sounds like a whine. It is caused by turning the engine off while the turbo is at full heat. It is rarely fatal. Next most common is noisy bearings caused by bad maitenance by previous owners. Start saveing for new turbo. My turbo has had a little of this noise for 5 years and has 2mm end float in the bearing but at 200000km well see how far it goes. Lastly and almost unique to 92 - 98 isuzus is heat shield failure around 160000km. This gives the whistle on shut off and is also fatal.

[munz]

RIIIIGGGHHTTT.... Option one, or two could be a possibility. This was the harmonic I was trying to explain in the first post I think.

And considering the guy who sold it to me, (I lived up a massive and steep long hill then) arrived to show me the vehicle, switched it straight off! Then proceeded to promptly run around the front wheels unlocking the hubs after I alluded to the fact his hubs were locked, and that's why he had trouble doing the U-Turn on my tar sealed driveway

This is a very nice example of Mu/Jazz, it looks good, runs well, but it is up to me to bring it up to scratch with maintenance after consideration of the previous owner.

J

[geeves]

From the book. Speeds under 80kph no wind down needed,100kph 1 minute,over 100kph or heavy hill work/towing 3 minutes. Its water cooled unlike early turbos.