So whilst I’ve been hard at work renovating my mk3 I’ve been running it on tick over to keep the battery charged. Yesterday whilst buzzing all of the flaky paint and oxidisation off my alloys the fuel light came on so off I went into the shed and got the fuel can I use for the lawn mower. That was my first mistake the second was putting the fuel into the car which almost immediately began spluttering and misfiring.
I’ve ordered a new fuel filter but can anybody tell me if the mk3 has a drain plug on the fuel tank and what other precautions I should take in ensuring I remove all of the contamination from the fuel system - God I feel such a numpty!
In the research I did the mk3 doesn’t have a fuel filter, just a sock in tank. Secondly, if you only put a jerry can of crappy fuel in then filling up the rest of the way with super should sort it out
With the fuel light just on you’ve got around 1 gallon say 25-30 miles of fuel left. Putting old fuel in, even say half a can will not mix well with the good fuel.
My lawnmower wouldn’t start on old fuel, new fuel it fired up straight off. Just think what your MX-5 engine is going through, as Dean says get some more decent fuel in, it should run ok.
We had a similiar problem with the E10 Ethanot added ICE powered machinery on our allotment site. We now religiously add some anti ethanol additive to all the 5L tanks as we fill them up with new fuel from the pumps. So far everything we have filled after a winter of non use has started first time and continued to run without any problems. We normally run them dry prior to winter so there is nothing in them over winter. We did try just adding it to the individual machines but realised that the fuel was going off in storage befoer it even got to the machine.
How do you know there is water in the fuel? If there is definitely any quantity of water in there then it’s probably best to drain the tank but you’ll probably never get it all out, but if you’ve just added a little old fuel it could just be bad if its been sat around a long time.
Short of disconnecting the fuel rail feed and diverting it into a bucket then putting power to the pump the easiest most convenient way is add as much high octane fuel (to full) as you can to get an acceptable quality to run reasonably then use it up sensibly without giving it too much stick. Once at half a tank fill up again etc and the dillution will be down to very little. If you only have a small amount of fuel in there then topping up to full should do wonders.
This happened recently, a member had rough running when going back to use the car after it had stood for a time, changed plugs, coils, sensors etc and no change, then added a fresh tank of super unleaded and it cured the running issues.
It’s up to you what you do, there are also octane boosters you can add if you’re worried about fuel quality that can reduce the chances of detonation, I use liquid moly if need be .
Thanks for the very detailed response, Dean, that helps a lot. The fuel was stored in the shed and the cap wasn’t particularly tight so I’m surmising that damp got in there but it could simply be poor quality fuel - it’s been sitting around for a minimum six months.
If the cap was on (even loosely, but on) it would only absorb a little from the atmosphere, no more than the car sitting with fuel in the tank I would think
Years ago we had the misfortune on a family holiday of stopping for petrol at a French supermarket and finding our later that the fuel was contaminated with water.
We spent the next two weeks with a car that kept lurching, losing power, gaining power and additionally howling from its’ exhaust.
Couple all this with accident damage to both the car and caravan, a distributor cap that exploded, a radiator hose that burst and an eventual final breakdown on the motorway that led to us being taken in convoy with a recovery lorry all the way to our ferry home and you can get the idea of what water in your fuel would be like We also arrived at most campsites on a recovery lorry (no occupants in the cab bar the driver, we were up on top in our car).
It wasn’t until we got back to the UK, broke down again, had the breakdown people out and them discovering the whole fuel system was full of water and petrol that everything got drained and sorted out.
Guys, massive thanks for your help with this issue.
I followed the advice given here (especially Dean S550) and drained some fuel off the car then filled with super unleaded. It ran like a bag of spanners for about five minutes, having to keep my foot on the throttle to stop it stalling but as the new fuel came through it kicked back in. Just getting the odd flutter when some poor quality fuel comes through but in the main it’s fine now and that’ll go as the old fuel burns off.
Brilliant stuff . This seems to be quite a common niggle with mx5s (stale fuel), most likely because they spend a long time laid up between bouts of regular use.
We also arrived at most campsites on a recovery lorry (no occupants in the cab bar the driver, we were up on top in our car).
