Fuel vaporisation???

wombat88

wombat88

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Out on the boat today, hot. The boat has a 50hp Suzuki outboard. After about 20 minutes at 3000 rpm the motor just died. No warning lights on the dial etc. A couple of goes and it restarted. All was well for the rest of the trip (apart from my nerves). Could this be down to fuel vaporisation on a hot day?
 
Just possible if the hose was in full sun ( Bpt around 35 to 38C ) there may be a variation between winter and summer grades. Refueler will be able to confirm or rubbish this suggestion
 
Yes there is a difference in fuel specs summer - winter ... but OP's problem - I do not think would be this.

If it was Diesel and occurred in winter - then could be summer spec diesel .... but with gasoline - extremely unlikely.

Difficult to say what it could be - but I think that restarted and ran ok may give us a clue .... first start - carb / injector pump + hoses may have been hot under the cover .... once its run and then restarted - they may have been cooled off by that initial fuel passage and water through system ??
 
wombat88 said:
Out on the boat today, hot. The boat has a 50hp Suzuki outboard. After about 20 minutes at 3000 rpm the motor just died. No warning lights on the dial etc. A couple of goes and it restarted. All was well for the rest of the trip (apart from my nerves). Could this be down to fuel vaporisation on a hot day?
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How do they cope on the Med? It's not that hot.
 
Unlikely I would think. Outboards of all descriptions run reliably in temperatures far above what you will be getting in the Channel Islands(I assume that's where you are). Whatever the ambient temperature is, the temperature under the lid will be in excess of that anyway and probably not vary that much and will be governed by the engine temp which is controlled by the thermostat. If the tank is external which I would expect then evaporation in the feed line would be the only other area to consider but I've never had it on my outboards running in ambient of up to 45 degrees in the summer here in Portugal. I have had a blip or two if I'd forgotten to pump the fuel bulb before starting the engine and there was a vapour lock in the feed tube but that would normally happen fairly soon after start up not 20 minutes later.
 
Thanks, I will cross vaporisation of the list and investigate other avenues.

Of late it has been behaving so well that I haven't used the fuel bulb...

Fuel tank is remote and lower than the engine.

and while I am at it I will change the fuel, some but not all of it has been in there a while. I doubt it is this, I would expect more of a missfire rather than a sort of 'stalling'.

What would be the symptoms of an 'end of life' low pressure pump?
 
Sudden stop with no spluttering? Maybe look at electrics. Bad intermittent L.T. connection? Then suddenly ok again. For a while until the next time. Intermittent electrical faults are always the most difficult to find. Until they fail completely. Then easier. May be worth inspecting all engine wiring loom connections for corrosion/bad connections. See what you find. In the absence of other clues that's what I would do to start with. May not be the answer but at least you've ruled something out.
 
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