DiscoClax Posted September 8, 2007 Share Posted September 8, 2007 OK, firstly, it's a D1 3.9 auto V8 (with dizzy) 8.1 comp, no cats no oxys. It's dual fuel, running a 42ltr petrol tank in the RHR wing with factory fuel pump and sender. Twin LPG tanks where the petrol tank used to be. Its a 14CUX EFI system with Lucas hot-wire (all engine and injection is factory standard, as built). The problem:- If I'm running on petrol and hit a sharp bump, like an aggressive speed hump/pot-hole or while off-road, the engine will just die or it'll stammer and cough with no power at a low very rough idle irrespective of throttle position. Generally recovers in a few seconds or after an ignition cycle. Has never done it when running on LPG, so I'd assume it's not an ignition related issue (it's an older "dumb" carby-type gas system with no interface to the EFI computer, so the fuel and ignition systems are stand-alone). I've replaced the fuel pump with a known good unit*, checked fuel/electrical connections at the rear end, ensured lines are clean, filters replaced, etc. No change. * Nothing seemed wrong with the old unit when I pulled it, but there was a fair amount of rust and crud in the swirlpot and stuck to the filter of the old pump. All squeaky clean now. I'm thinking the EFI computer is copping a jolt and somehow dropping out. Ba$tard of a thing to get at, so I don't really want to pull the bugger out unless really necessary. However I have heard that they are problematic? I'm looking to convert to vapour injection, so I've got to get the EFI working properly first. As an addendum, it's never really run totally properly on petrol. Starts OK, but has gone through random phases when it over-fuels badly, currently has a hole on tip-in and sometimes loses power and misses if held at WOT high revs for a while like when overtaking on a hill). Is sluggish and doughy when cold and feels like its overfuelling (like an oversize cab). Quality 98RON fuel used exclusively and tank, lines and filter all cleaned/replaced recently. Runs fine on LPG with none of these issues. Economy on LPG is around the 20-22ltrs/100kms (~13mpg) mark - 90% freeway, and about 18-20 ltrs/100kms (~15mph) on petrol for same usage, which seems on the high-side to me, but it's generally pretty consistent. Note that my vac adv isn't working at the moment either (split diaphragm) - refer wanted items in the classified section Sorry this is so long, but it (hopefully) reduces the number of question and answer iterations required. I'd welcome others thoughts and feedback (excluding converting to diseasal...) Quote Link to comment Share on other sites More sharing options...
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