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Discussion Starter #1
Hey everyone.
I am having an issue with a GU 98/99 4.5 petrol injected.
Its running fine around town, out on the tracks no worries and doesn't seem to be down on power. BUT.......
When we take it up a good size hill run it will run fine with plenty of power for about 1/2 to 1 minute and then start to sound and feel as if its running out of fuel. It doesnt ever stall just looses power.
(FYI) - This truck has a 6" lift with 35's. no mods to the engine other than the exhaust.

My thoughts are electrical rather than fuel or pump as it does it when the tank is full or half full.

Lend me your thoughts.
 

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Ive noticed the same thing with mine. No hassles on the flats, no hassles in the dirt but hit a hill and she loses all her guts. These are just regular hills approximately 30 degree incline.If I put my boot into it the revs go up but very little impact on speed?? So I'm also interested to find out too.
 

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I can't see any issues that would create such a power loss, without a noticable miss etc.

They are a very simple engine. If you are concerned enough - replace dizzy cap, rotor button, leads, plugs, fuel filter, air filter.

If you've done all of that and still have the issue then it would be my initial thought, you are expecting too much from the TB45. They are gutless on hills. I've owned one for 6 years and the engine is maintained like an aircraft jet. It doesn't like hills.

I would start with the fuel filter, but a TB45 with 6" of lift pushing 35s on standard gearing - it would be lucky to hold 100kph on a slight incline.
 

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Discussion Starter #4
She has gear reductions, But the issue isnt just loosing power, it is feeling like its running out of fuel. it starts to cough and fart a little, not major amounts then when its level again it runs fine.
Again only on hills is there an issue.
Its like its struggleing to get the fuel it needs to keep the power down.
 

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On my Dual Fuel 4.5L
When running on petrol from the 75L sub tank, when fuel level gets low, have the same problem (fuel starvation) when driving a bit harder around corners, Up Hills or when braking hard.
Some times it stalls, some times it keeps going after a little hiccup.

I put this down to the low fuel level and swishing around in the bottom of the tank exposes the fuel pump to air.
 

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Discussion Starter #6
Thats what we were thinking jimako,
A little bit of air getting into the fuel system when its on a hill while the fuel is lowish. But then it started doing it even with a near full tank.

With the 4.5's can anyone tell me do they run some sort of senser that could be giving a wrong message when the truck goes up on a hill. or should i focus attention to the fuel pump and or pickup.

Why couldn't it be a diesel. At least i know them.

Cheers.
 

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Maybe running out of fuel supply with the prolonged high fuel rate required up hill. Possible partially blocked filter, suction filter on pump or lack of available flow rate from pump. You could rig a gauge to the cab and check the fuel pressure whilst driving.
 

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A faulty fuel reg could cause those symptoms, perhaps a slight change in constant load and vacuum under the long uphill slog could trigger a slight lean out ?

This would explain why it does not happen on more rapid throttle movement, or on the flat (with less load)






As per what FIG JAM said about testing fuel pressure while driving, this could be a good place to start
 

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Discussion Starter #9
Some great ideas there, will have a test over the weekend and see what we come up with.
I might even just be down to as FIG JAM said a patially blocked filter.
Will start there and then try some of the other ideas.

Cheers Guys, Really appriciate the help.
 

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Hey everyone.
I am having an issue with a GU 98/99 4.5 petrol injected.
Its running fine around town, out on the tracks no worries and doesn't seem to be down on power. BUT.......
When we take it up a good size hill run it will run fine with plenty of power for about 1/2 to 1 minute and then start to sound and feel as if its running out of fuel. It doesnt ever stall just looses power.
(FYI) - This truck has a 6" lift with 35's. no mods to the engine other than the exhaust.

My thoughts are electrical rather than fuel or pump as it does it when the tank is full or half full.

Lend me your thoughts.
Mine runs great uphills , even more so since the extractors/exhaust/snorkel combo.

Hey it aint a ferrari but i love it.

Good luck..

Dazza
 

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is she auto or manual ? im haven trouble with my auto 4.5 no power on steep hills in 4b .fitted a 5ltr v8 same problem engine runnen sweet as a nut just wont get the power through the auto and no one nos why
 

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Discussion Starter #12
She is auto.
With gear reductions.
 

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Discussion Starter #13
Had a bit of a test,
i wanted to see if the issue was to do with not enough fuel,
With a loaded trailer and truck, took the car from a standing start to 100kph (flat to the floor). No problems. If there was a blockage somewhere then it should show its head doing this. same if its a fuel starvation problem, it SHOULD have shown its head.
Took the car 4x4ing with no load on the back. Up the hill track she goes (quite a steep track), full tank of fuel, giving it some, gets close to the top and starts to cough and splutter as if its running out of fuel.
So it is something to do with the angle she is on that regardless of the fuel level it just does not seem to be getting it to the engine.
It seems unlikley that there would be a hole at the top of the suction pipe but that is what it feels like, as if there is air getting sucked in when she is up on the steep angles.
 

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Discussion Starter #14
Lend me your thoughts
 

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Im trying to think of something but it just wiered.

Maybee air in the fuel filter, so when u go up the air gets sucked in, but that should have cleared by now.

You should remove the pump for a good look at it.

Could it be a loose electrical connection that looses connectivity when going up?

Hows the level of the transmission fluid ? if its low and going up hill the fluid maybe drains back and out of the convertor causing some power loss ?
 

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Maybe some sludge/bits of crap in the fuel tank that only moves when on the angle, and so blocks the pick-up on steep inclines ?

Easy to pull the pump out & check this one, and rule it out as a cause anyway
 

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Discussion Starter #17
Yeah, im thinking that this is the only way to eliminate the fuel tank and pump, by taking it out and just having a look.
 
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