Morning people - I have an issue. I went to start the van the other day only to find that my half a tank of petrol had siphoned into the engine! I didn't know this when I turned the engine over...its was a struggle then it started and was rough....I went to the back of the van only to find it smoking and a massive pool of petrol on the floor. The engine was full to the brim with petrol. I took the sump plug out and whooosh all the dirty black petrol came out. I refilled with oil and all is fine again now. I've had Vdubs for over 18 years and this has never happened before. Has anyone got any clues as to why this could have happened? How has all that petrol got in the engine? I've got a 1600 twin port with dual Webers ICT's on. Any thoughts would be apprecaited! cheers
petrol Siphoning into engine...weird
- Thread starter MMMC
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could be a leaky fuel pump, or a stuck float valve in the carb.
or your tank is not vented properly and the warmer weather is expanding the fuel forcing it past the float valves.
Look down the carb barrel you should be able to see if fuel is running down the throat, if not its more likely to be the fuel pump
or your tank is not vented properly and the warmer weather is expanding the fuel forcing it past the float valves.
Look down the carb barrel you should be able to see if fuel is running down the throat, if not its more likely to be the fuel pump
Araon
Well-known member
atleast the engine should be clean..... 
silver lining and all that
I would hazard a guess at a fuel pump, fuel expansion shouldnt be that great to push through the filter upto the carb/s back down into the heads then past the pistons....
not a good situation.....
silver lining and all thatI would hazard a guess at a fuel pump, fuel expansion shouldnt be that great to push through the filter upto the carb/s back down into the heads then past the pistons....
not a good situation.....
Your right about the silver lining!
I'm interested in your fuel pump senerio. Should the fuel pump stop the flow of petrol altogether when off or can the fuel make its way through?
I guess the other option is that somehow there is a vacuum created in the engine that is sucking the fuel through but surely the oil breather pipe should stop this?
I'm still bemushed by all this!
I'm interested in your fuel pump senerio. Should the fuel pump stop the flow of petrol altogether when off or can the fuel make its way through?
I guess the other option is that somehow there is a vacuum created in the engine that is sucking the fuel through but surely the oil breather pipe should stop this?
I'm still bemushed by all this!
Araon
Well-known member
Yeah I'm bemushed also :lol:
in theory your lifting the fuel back up to the carb/s so it should require pumping....
if theres a leak where the rod fits to the diahragm then it will flow into the case with relative ease...
unlikely that the engines got that strong a vacuum but you may have a few issues, quite often the breather is neglected and either kinked / blocked, as mentioned the float may well be stuck thereby not shutting off the in flow etc...
good luck
in theory your lifting the fuel back up to the carb/s so it should require pumping....
if theres a leak where the rod fits to the diahragm then it will flow into the case with relative ease...
unlikely that the engines got that strong a vacuum but you may have a few issues, quite often the breather is neglected and either kinked / blocked, as mentioned the float may well be stuck thereby not shutting off the in flow etc...
good luck
Araon
Well-known member
30 mins to remove the pump and strip it down...piece of mind...
Had the same thing with mine and still going thru the list of what it could be.Mine has got an electric fuel pump(pushing too much fuel thru ?? ) so I've sent off for a fuel regualtor,had the carbs off (Solex) and one had a liitle bit of fuel in the float so that was replaced.I'll be watching this thread..........good luck
shaun said:
Thats interesting - what was the explanation behind that? I do have a newish fuel cap on (6 months).
Araon - I think your right a strip down of the pump would certainly rule that out...
Mole - did it happen to you just the once or multiply time?
Trikky2
Well-known member
On a bay, when theres a reasonable amount of fuel in the tank, the level is higher than the carb. Even more so if the vehicle is parked facing up hill.
Hence it is possible for the fuel to enter the engine. Its not siphoning - its simply flowing. Most likely cause is the needle valve in the carb. Either worn, or a bit of dirt jamming it open, or the float not closing it fully because the float is jamming or partially filled with petrol (they can get pinhole leaks in them - just give it a shake and if its got a bit of fuel in it you can tell).
Easy enough to fix.
Once i had one where the owner had re-assembled the carb and left out the washer under the needle valve which caused a similar problem.
Hence it is possible for the fuel to enter the engine. Its not siphoning - its simply flowing. Most likely cause is the needle valve in the carb. Either worn, or a bit of dirt jamming it open, or the float not closing it fully because the float is jamming or partially filled with petrol (they can get pinhole leaks in them - just give it a shake and if its got a bit of fuel in it you can tell).
Easy enough to fix.
Once i had one where the owner had re-assembled the carb and left out the washer under the needle valve which caused a similar problem.
The tank vents through the cap on a splitty, i found that after i had run the van and parked up (engine off) , the heat would build up in the engine bay ,which in turn would heat up the petrol tank and expand the fuel, the fuel had no where to go other than past the float valves (as the fuel cap was a new one from a dealer with a vw logo and wouldn't vent.)
I fitted an old cap from a swap meet and hey presto problem solved.
I fitted an old cap from a swap meet and hey presto problem solved.
currylager
Well-known member
It is highly unlikely there is anything wrong with your fuelling system, the 34ict's have crap needle valves which pass fuel through even minimal pressure,the same happened to me last year. To solve this problem permanently all you need to do is buy a fuel cut off solenoid like those used in the LPG conversion kits (around £25) and fit it in the fuel line just before the T piece for you carbs. Connect the negative wire to your fan housing or similar earth and the positive to the 12 volt supply on the ignition coil. This means that the fuel pressure is relieved when the engine is off, and hey presto No more problems .
James
.James
currylager said:It is highly unlikely there is anything wrong with your fuelling system, the 34ict's have crap needle valves which pass fuel through even minimal pressure,the same happened to me last year. To solve this problem permanently all you need to do is buy a fuel cut off solenoid like those used in the LPG conversion kits (around £25) and fit it in the fuel line just before the T piece for you carbs. Connect the negative wire to your fan housing or similar earth and the positive to the 12 volt supply on the ignition coil. This means that the fuel pressure is relieved when the engine is off, and hey presto No more problems
James
Nice one James - sounds like a plan to me. Any idea where I can get one?
Thanks to everyone for the advise and tips.
currylager
Well-known member
Hi mate,
You need something like this, but i'm sure you can get it cheaper tho
http://cgi.ebay.co.uk/Anti-theft-Fuel-CUT-OFF-Solenoid-Valve-12v-3-5mm-dia_W0QQitemZ390038413742QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item390038413742&_trksid=p3286.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318" onclick="window.open(this.href);return false;
James
You need something like this, but i'm sure you can get it cheaper tho
http://cgi.ebay.co.uk/Anti-theft-Fuel-CUT-OFF-Solenoid-Valve-12v-3-5mm-dia_W0QQitemZ390038413742QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item390038413742&_trksid=p3286.c0.m14&_trkparms=72%3A1683%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318" onclick="window.open(this.href);return false;
James
