Always keep 1/4 of a tank of Petrol in reserve

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steve_96 · #1 Post by **steve_96** » Thu Jan 12, 2006 1:12 am

Always keep at least 1/4 of a tank of Petrol in reserve. Why would we say that? On most conversions the Petrol pump is still running whilst using LPG (for good reasons not discussed here). If the tank runs dry whilst you are running the engine on LPG the Petrol pump can be burned right out as it relies on Petrol to lubricate its bearings and cool it down. Fuel 'slosh' when going round corners may leave a Petrol pump to run dry if there is only a gallon or so in your tank. This is why we recommend 1/4 of a tank to keep the pump 'wet' at all times. Also make sure you use and replenish that 1/4 of a tank of Petrol in rotation - Petrol over 3 months old will have degraded to a greater or lesser extent and may not even be capable of running the engine at all! NOT what you want from a reserve fuel! Just a small part of 'Hints for LPG Motoring' from the website of <a href="http://www.go-lpg.co.uk" target=_top>www.go-lpg.co.uk</a>

sm200sx · #2 Post by **sm200sx** » Thu Jan 12, 2006 10:49 am

I can vouch for this, and others (theres a discussion on here somewhere) as I'm not the only one to have had to have replaced the fuel pump due to cavitation.

#3 Post by **admin** » Thu Jan 12, 2006 11:42 am

Happened too me Steve, I had to replace the pump on my Discovery.

cubicincubi · #4 Post by **cubicincubi** » Thu Jan 12, 2006 12:33 pm

yup, previous owner had to replace both fuel pumps on the merc. As a rule I always top up the petrol to 1/2 tank when filling up with lpg to round it off to £20/30. I Always fill up the lpg tank once it reaches 1/2 way aswell. The petrol pumps get good use as we always do the first few miles on unleaded before switching over and we do the last mile or so on petrol aswell to let the valves cool before turning the engine off.

richy_boy · #6 Post by **richy_boy** » Thu Jan 12, 2006 2:16 pm

I'm with bob on this one. <IMG SRC="http://www.my90.co.uk/lpgforum/clipart/happy.gif" ALT=":-)" BORDER=0> Cooling valves by running on fuel is a myth. Your best bet is to turn the engine off! Rich

cubicincubi · #7 Post by **cubicincubi** » Thu Jan 12, 2006 4:29 pm

just seems practical to allow them to cool with coolant pumping past them and petrol being burned rather than relying on ambient temperatures on shut down, much like cooling off periods for a turbo after high temps. It also allows the petrol pumps (the car has two) to have a brief period of operation every time the car is driven. It may sound daft and I suspect any cooling is neglible - I just like the idea. Bob - your petrol pumps may expire unless they get use. I for one don't want to fork out what it cost the previous owner to have another pair fitted. Also how come you don't reach normal operating temps on petrol? how do you run to gas from ignition? I was under the impression it was highly advisable to get up to temps with petrol to stop freezing and component stress?

richy_boy · #8 Post by **richy_boy** » Thu Jan 12, 2006 4:36 pm

Ahh, I understand you thinking now, but you need to remember when running on petrol (to cool) your valves are facing red hot explosions from ignuting petrol, which is a damn site hotter than any air from within a turned off engine. The turbo cooling thing is slightly different as it runs much hotter than any engine component, so hot infact that the oil can boil unless allowed to cool down a bit. Once the oil has got this hot it leaves nasty deposits in the turbo which can make its way into the bearings / shaft causing damage. If Bob hasn't used petrol for so long, I doubt he's too bothered about a dead pump either <IMG SRC="http://www.my90.co.uk/lpgforum/clipart/happy.gif" ALT=":-)" BORDER=0> Although I'm interested how he starts the car on a cold winters day, I'd of thought i would be lump as! Rich

cubicincubi · #9 Post by **cubicincubi** » Thu Jan 12, 2006 5:49 pm

re turbo shaft damage - don't I know it, my GT4 bearing was well fubar'd earlier last year in the summer, got so much of a wobble on at a squillion rpm that one of the exhaust turbine blades more or less shattered. Limped home with white smoke pouring out the exhaust from all the burning oil. lol. back to valves, I just kinda figured that if shut down on gas the valves are gonna be very hot and oil may carbonise on them. anyhow it makes sense to take it easy on the last stretch in any vehicle really. Back to Bob - I just don't understand how you dont use any petrol. Rich - i'm quite interested as to what set up your running on the SX and how and when it comes into use. Most folks on the GT4OC seem to suggest LPG on the celica gt4 is impossible. I think not. have you got a website set up or any links to your gear? cheers

martin_hodnett · #10 Post by **martin_hodnett** » Thu Jan 12, 2006 6:11 pm

I very rarely run my old rover 214 on petrol, always starts on gas whatever the weather - in fact, starts better on gas in cold weather. Perhaps because I have a small engine (in comparison to you good folks!)it doesn't suck so much gas through to freeze up fast and the evaporator gets heated quickly. In practice, when I switch on the ignition, I switch to petrol then back to gas position before cranking the engine. This lets it start straight away on gas. Could be I just have an old system that lets me do it. (Landi Renzo, single point, open loop). Martin

claicerrig · #15 Post by **claicerrig** » Fri Jan 13, 2006 8:07 pm

I think there are now 4 or 5 Nissan 200 sx`s running LPG now .All are in various states of tune.I have been running LPG in mine for about 18 mths now with no problems apart from changing 2 fuel pumps and the fact that i cant get above 3500 rpm before the change over to petrol but that is through limataions to the system fitted not the car

sm200sx · #18 Post by **sm200sx** » Mon Jan 23, 2006 2:48 pm

Yes, tell them, they will need to se the certificate of install. No, it shouldnt cost anything with most insurers.