4.8l losing power under load GU

[sandy]

Hi all my patrol is idling well and revs fine until I take it for a drive, as soon as I hit the accelerator is loses power and acts like it it is missing. Two years ago I serviced injectors, repalced coils and plugs all nissan genuine. a few months back I filled up at Jindabyne and as soon as I hit the hills towards Threadbo it lost total power uphills. on the way home the fuel filter was replaced at Goulburn and it was quite dirty. recently I drove it around Sydney and it was ok until I filled up again and again it started to lose power when the accelerator pressed.

so far I have replaced injectors with brand new ones as well as the fuel filter and still it misbehaves. ARB has checked the plugs (gap needed adjustment), checked fuel pressure at the rails and was about 35psi at idle and 40 when throttle pressed. it is idling great and even when throttle pressed it seems ok UNTIL it is driven and it loses power. Any ideas as to what it can be? I have been told it still can be the fuel pump? anyone know of a reliable service centre in Sydney that I can take it to? or provide any ideas as to what can be checked next? HELP PLEASE!!!

[BigRAWesty]

Has anyone looked at vacuum hoses?
This age of car imo any rubber hose, replace it.
Any micro split in the hose will effect performance.
Imo replace all intake hoses and vacuum hoses.

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[sandy]

Hi all my patrol is idling well and revs fine until I take it for a drive, as soon as I hit the accelerator is loses power and acts like it it is missing. Two years ago I serviced injectors, repalced coils and plugs all nissan genuine. a few months back I filled up at Jindabyne and as soon as I hit the hills towards Threadbo it lost total power uphills. on the way home the fuel filter was replaced at Goulburn and it was quite dirty. recently I drove it around Sydney and it was ok until I filled up again and again it started to lose power when the accelerator pressed.

so far I have replaced injectors with brand new ones as well as the fuel filter and still it misbehaves. ARB has checked the plugs (gap needed adjustment), checked fuel pressure at the rails and was about 35psi at idle and 40 when throttle pressed. it is idling great and even when throttle pressed it seems ok UNTIL it is driven and it loses power. Any ideas as to what it can be? I have been told it still can be the fuel pump? anyone know of a reliable service centre in Sydney that I can take it to? or provide any ideas as to what can be checked next? HELP PLEASE!!!

all I had the fuel pump replaced, the fuel tanks flushed, MAF sensor replaced , Oyxgen sensors V, and whilst at it, replaced the spark plugs and coils (which were replaced 2 years ago but turns out, back then, it was an injector issue not the coils and hence kept as spares). Now my 4wd is running well. yeah!!!! so combination of fuel pump and a faulty coil were the cause, I never thought of replacing the coils since they were brand new nissan genuine coils. FYI I told ARB not to check the coils as a result, thank goodness ARB ignored me, checked and replaced with used spare coils anyway. they also swapped back the coils to confirm if the misfires came back, and it did, so now I know one the new coils replaced 2 years ago is faulty, when revs are high. Thanks to ARB, they kept at it to find the fault, sadly the 2003 GU OBD11/CPU information is very limited, there were no engine or error codes, so finding the answer was challenging was for them.

I am going to replace coil hardness as well, as recommended by one member, as they tend to become fragile after time and can cause miscellaneous misfires etc. anyhow, thanks for your help

[mudski]

Sounds like to me you have a fuel tank that needs a clean. On idle your not drawing up much fuel through the pickup in the tank. As soon as you give it some load the pickup may be also trying to suck up some dirt or theres already crap in the pickup or fuel line somewhere.

If it were me, I would be dropping the tank and cleaning it out, also the pickup tube and all fuel lines.

The TB48's actually have an intake fuel pump with a gauze sock like filter on it. My moneys on this being a wee bit dirty.
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