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Weird fuel starvation issue. Electrical or mechanical?..

Old Greg

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Joined
Nov 15, 2022
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4
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new_zealand
Hi folks,
Newbie here with an issue thats been driving me nuts.
Any suggestions very gratefully received.

1997 Toyota Landcruiser Prado 90 series
Engine 1KZ-TE

Fault:
Began as increasingly difficult to start. Changed the glowplugs but no improvement.
Did a full service and changed all filters including fuel filter.
Considered it could be air in the line and so bled system up to injectors.
No improvement.

Radio stopped working

Still suspecting fuel feed issue.

Checked the SPV but it showed correct resistance across terminals.

Fault continued to deteriorate so now very hard to start, little or no power at low revs from standstill (eg at traffic lights). Ie put it in D and hit the pedal but no rev increase. Put it in N, then raise revs above 1000, then drop into Drive and she’ll pull away.
Fault seems to get worse the hotter the engine gets

Had a total power fail eg parked one day to visit shop, came out and absolutely nothing. No lights on dash at all. Called AA who diagnosed completely corroded connection from battery positive to main fuse box (RHS under bonnet)

Front left power outlet stopped working.

Very hard to start even when hot, and requires excessive cranking with pedal to the floor. Once it catches will idle rough at about 600rpm for about 1-2 mins, then pick up to normal 800rpm.

Any attempt to increase revs before the 1-2 mins has elapsed results in a drop in revs, not an increase

Checked the ECU and saw no obvious signs of damage (eg blown capacitors etc)

Will now occasionally stall when hot and travelling downhill eg without power/throttle on.

In reverse, even workaround of raising revs in neutral then dropping into gear, no longer works unless keeping revs high and reversing at speed. (Obvs not a good idea!)

Anyone got any ideas?
Cheers


Checked main fuse box and power not reaching all fuse positions: no power to front power outlet or radio fuse holders. Power reaching ECD though.
 
I would disconnect and isolate your tow socket wiring because thats known to rot and cause all sorts of magical mystery electrical problems .

Perhaps then start searching the truck (via the internet) for earth/ground wires that might be bad .

I can't imagine the battery itself causing these faults but i'd borrow one just to be certain .
 
Fuel can't burn without air , is your throttle body butterfly so clogged up with egr crap that its jamming shut ?
 
Had a total power fail eg parked one day to visit shop, came out and absolutely nothing. No lights on dash at all. Called AA who diagnosed completely corroded connection from battery positive to main fuse box (RHS under bonnet)

How did you get it going, did you put a new wire/connection in to the fuse box and then it was OK?

Checked main fuse box and power not reaching all fuse positions: no power to front power outlet or radio fuse holders. Power reaching ECD though.

This sounds significant to me.... is the fuse box corroded or otherwise fkd internally?
 
Take the fuse box off see whats going on behind it .
 
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I had something slightly similar a few years back, the rubber diaphragm in the top of the fuel filter housing had perished and started letting air in. Your symptoms sound the same, cutting out going downhill, and not starting with a warm engine. Installed a whole new fuel filter housing and it's been ok since. Mine's also a '97.
As Shayne said above the trailer socket wiring can be full of gremlins too. Mine leaves the headlights on mysteriously after getting wet once or twice a year. My simple farmer diy solution is to either take the fuse/relay out for the headlights or disconnect the negative battery terminal.
 
Hey chaps. Ok. So couldn't take it any longer and the problem was getting worse, so i took it to a specialist. Infuriatingly it took him less than 2 hours to fix lol.
Turns out an adjustment on the on the back of the fuel pump had mysteriously changed position and altered/restricted the fuel flow. Can that even happen on its own??
Now in my ignorance i didn't even know there was a fuel pump. Assumed it was all via the injector (Still don't know where it is !)

As for the electrics, weirdness continues and i think you're right that something is definitely up with the fuse box, so that and the towbar electrics are going to get a work over next.

PS can anyone tell me why i can't download the manuals/schematics?

Cheers
 
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