Re: COULD SOMEONE HELP (archive)

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In Reply to: COULD SOMEONE HELP posted by Paul Ash on December 05, 2000 at 08:18:25:

OK, remove the sensor and clean:
0) get car on level in well ventilated area
1) remove trunk liner till you see the cover on the floor ( the black metal one with 6-7 screws to the right of the spare wheel well.
2) remove the bulb from the courtesy lights in the trunk - no spark/flame hazard
3) remove the plate - it doesn't go into the tank yet, so don't go mad about fumes yet
4) you should now see the access palte to the tank
5) disconnect the wiring harness - slide the metal "frame" horizontally back towards the back of the car - this will "lift" the connector from the block. Jam the connector out of the way in by the spare.
6) get some cheap electrical tape handy
7) remove the two hoses - beware residual petrol pressure (not much on mine after having run the engine within the last 5mins). Have a rag to soak up the spillage. DO NOT LOSE the circlip clamps down the hoses!! Give each hose a couple of turns of tape and leave a 6inch "fly" end and tape this to the floor of the trunk to keep the hose up and out of the way on the side it came off
8) get a 10mm socket and undo the 8 nuts holding the access plate to the tank. Might pay to clean it before you get any dirt in the tank too.
9) pull up the plate the first 1-2 inches firmly to release the gasket - mine styed with the plate.
10) two hands from now on
11) lift the plate up and out. Beware the petrol trapped in the sensor body and the hoses - take it slowly and you can get most of it to drain back into the tank. Be careful of the end of the sensor ( the sensor is a tube about 8" long and aboout 2" diameter, with a bigger "settling tank" at the bottom) - a bit of a squeeze with the hoses too.
12) get the sensor/access plate clear, only hoses going into the tank
13) get you hand into the tank, and follow the hoses to the pump. Follow the pump till you feel the flange in the tank it sits in, then come back up to the pump mounting collar and fing the two plastic tabs (180 degrees apart) that lock the pump in; squeeze together and then lift the pump out
14) lift the pump out - you can use the hoses (gently) but DON'T use the wiring.
15) get the whole sensor/pump assembly out of the trunk. Suggest you wrap the input gauze filter on the pump in a clean rag to protect it from being accidentally torn/poked through

OK, now clean the sensor:
1) get the small collar nut off the bottom of the sensor tube - don't lose it
2) pull the sensor tube off the metal tang it's slid onto ( the one from the underside of the access plate). BE CAREFUL OF THE VERY FINE SENSOR WIRES.
3) Now you can see the 3 sensor wires - the middle one is just for the low fuel level contacts, so it doesn't matter if it's "slack". The other 2 fine ones are the ones you want.
4) check the 2 fine wires are complete and soldered to their mountings. I cleaned mine with an isopropyl-alcohol screen wipe pad, and then ran the thickness of the pad/sheet between the wires and the 2 contacts (per each side of the float, 4 total) on each wire
4b) use the pad to clean the harness connector pins as best you can, and the plug too (Although with mine I found the best undersize jewellers' screwdriver and scratched out the insides of the plg connections too; the total sensor resistance at full-empty is only something like 60-70 ohms, so any bad connection (slight resistance) is going to indicate as a prematurely empty tank...
5) rinse out any silt in the sensor body with clean petrol and discard the dregs; the "lid" on the baffle chamber can be gently popped up enough to clean in there too.

Reassemble carefully; make sure the pump tangs are engaged fully (you don't want a pump with LIVE ELECTRICAL CONNECTIONS floating loose in a metal tank full of petrol vapor); take care with the hose circlips; spray the access plate with a rustproofer if rusting (mine was) but AFTER reconnecting the electrics.

DO NOT LET THE OUTSIDE OF THE PETROL LINES STAY WET WITH PETROL. The outers of petrol lines are not usually proof from softening from petrol, as tey shouldn't see any of it - only the insides should. Don't let them get soft/sticky.

General conclusions:
- better linearity now - not perfect, but does indicate in the 0 to 1/4 range now!!
- driving with the headlights and aircon in heavy, slow traffic seems to have pulled my battery down; the movement with the headlights didn't occur with the engin running and/or the battery fully charged (daily running without headlights)
- OBC range seems to be more relevant now, although still varys up and down (I think this is the recalc interval where the MPG that goes into the range calc seems to be refreshed about 5 times more often than the MPG shown via the OBC).

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