fuel issues.

MY_STI · Post by **MY_STI** » Fri Dec 30, 2005 8:01 pm

On a recent 4wd outing, my ea81t has developed a problem running on petrol, it is running rough, kind of feels like its down a cylinder, but its constant, not 'uneven', also very down on power, and very hungry on the juice, fuel can be smelt at the tailend, and it was running cool (no more than 1/4 offroad, no thermos) I presume due to a very rich mixture?
water temp (ecu reading) was down around 40c

my reasoning for the fuel being the problem is that it hasnt seemed to change the running when on LPG.

pulled each injector plug off indivdually, and they all make a difference, so i assume the loom side is ok, and each injector was doing someting.
swapped the Oxy sensor (used), no noticeable change
cleaned the ignition system for good measure, plugs were fairly carboned, but it made little difference.
swapped injectors (were 1.8 camira) to RB30 injectors (used), no blockages in the fuel rails either, no luck there.

had a short run today, and the engine heated up to operating temp at about the rate it usually does (on gas) and the ecu temp was all good, but it made little difference to the fuel problem.

so i am down to;
resticted return, either the pressure reg itself or a blockage in the line to the surge tank resulting in to much pressure and to much fuel
or
contaminated fuel, the fuel was 'premium' (95, no 98 around here) from the usual haunt, there were, however, some water crossings over the tyre in depth (27" kang) is it possible that water could have found its way in to the tank?

I will test these tomorrow, and prob another efi pump for something to do,
but failing this i am all out of ideas, except try some more oxy sensors.

any ideas, suggestions or especially solutions are most welcome

thanks

MUDRAT · Post by **MUDRAT** » Fri Dec 30, 2005 8:16 pm

My next port of call would be the fuel pump and filters.

Suby Wan Kenobi · Post by **Suby Wan Kenobi** » Fri Dec 30, 2005 9:42 pm

Dont know what ECU setup you are using but if it is OEM subaru early 3 plug type then you can just unplug the O2 sensor as it will then not fatten up the mix thinking its lean, later ones and libertys work the other way (no sognal must be lean).

Generally if it has an OEM setup the water temp sender is always the culprit with either corroded terminals or a loose wire it is odd, even with then being as old as they are for them to break.

if you have an OEM setup the other place to look is the air temp sensor in the AFM of the spring in the AFM may have snapped in which case it will run rich and doughy.

fredsub · Post by **fredsub** » Fri Dec 30, 2005 10:22 pm

if the fuel pump is running poorly, ie not delivering its pressure or erratic, it has those symtoms, even to stalling at times. and yes it uses more fuel!!.....my guess there is that the fuel does not get atomised sufficiently, and liquid fuel does not burn too well.
Of course check the filters, its they that could be clogged up.

MY_STI · Post by **MY_STI** » Sat Dec 31, 2005 7:56 am

thanks guys,

efi filter is ok, i can blow through it much the same as when it was new anyway.

ECU is an injec em1 fuel only job http://www.injec.com/
which is MAP based so no AFM, water temp sensor connections are good, O2 senor is single wire.

will try another pump shortly

is there a reasonbly cheap way a fuel pressure gauge could be made up?, another oil pressure sender switched to the gauge maybe, or would the gauge not respond fast enough?