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Mystery problem and BP is to blame!

Posted: Mon Feb 03, 2020 10:32 am
by mlb50
One fine Sunday I started up the trusty B50, it was very low on petrol so off to the local BP servo. Filled it up, started and suddenly went all fluffy and puff stopped. Tried kicking over and over, then tickled it to flooding and it started but as soon as I put a bit of throttle on....puff puff stop.

Embarrased, a half mile push home...uphill of course. Left it for a couple of weeks and then yesterday got into the diagnosis.

Spark plug good. Carb removed and throughly cleaned. Timing checked, spot on. Battery 100%. Strong spark, valve clearance correct, compression good. NO START.

So, decided to take the 850 Commando out instead. But its really low on fuel, so I salvaged the contents of the B50 tank. Just happened to notice the fuel colour was a deeper shade of yellow and the smell...not really sure it was 98 octane...but who knows its "modern fuel". So tipped it in and went to the standard 850 starting procedure. Yes, it fired up...ran on choke well for about 20 seconds and then fluff, puff, and died as soon as I put the choke off. A fair bit of smoke was coming out the exhaust too....never had that before. Tried again, starts on full choke then runs rough and dies.

OK, so me thinks - the only thing that changed on both the B50 and Commando was the BP petrol...or was it really 98 octane? Did i accidentaly use the wrong bowser? Anyway, now with Shell 98 that looks and smells like real petrol, all is happy. So either I used the wrong bowser (unlikely) or some slacker has contaminated the BP bunkers.

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 03, 2020 4:13 pm
by madsundaysurvivor
As you say it seems to be a problem of contamination of the tank at the gas station.
In the past sometimes it happened that gasoline mixed with water from the tank when it was almost empty.
If it were a diesel vehicle this would be a big problem.
You should ask at the gas station if they have had complaints from any other customer.
sometimes it can happen and the gas station insurance must pay for the repair

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 03, 2020 7:11 pm
by Jeff K
We have had a problem here in the USA with gas, ever since they started mixing 10% ethanol in it. It goes "flat" very fast, I have found any gas that has been sitting for a month or more is suspect. The ethanol suck the moisture out of the air and retains it. Hydroscopic I think is the term.
Jeff

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 03, 2020 10:01 pm
by beat
mlb50 wrote:
Mon Feb 03, 2020 10:32 am
as soon as I put a bit of throttle on....puff puff stop.
sounds for diesel for me.
at least, by 50% to 50 %, - mine one was still running, - but no power in the wheel :cry:

beat

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 03, 2020 10:40 pm
by skippy
I use 98 in all my small engines because its the only thing that lasts in the tank. I had to ride home after running out of fuel once after my mate gave me some of his 91 and it was crawl and steady on the throttle or massive pinking.

Re: Mystery problem and BP is to blame!

Posted: Fri Feb 14, 2020 7:15 pm
by tridentperu
I had exactly this problem with my B44, but this time it was Shell to blame for not labelling it clearly enough..............I had filled up with diesel - got about 200 yards and that was all it would do. Push home - kick myself, refill with petrol, as good as new!

Re: Mystery problem and BP is to blame!

Posted: Sat Feb 15, 2020 10:10 pm
by beat
tridentperu wrote:
Fri Feb 14, 2020 7:15 pm
Push home - kick myself, refill with petrol, as good as new!
:mrgreen: :mrgreen: :mrgreen:
mlb50 wrote:
Mon Feb 03, 2020 10:32 am
tickled it to flooding and it started but as soon as I put a bit of throttle on....puff puff stop.
( a drop of water in the carbi bowl dos the same ) :oops:

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 17, 2020 8:05 am
by mlb50
It definelty was shit ''petrol''.

I drained both BSA and Commando tanks into a white enamel bowl. The fuel was a orange colour and strange smell .

The replacement fuel was Shell 95 - this was very pale lime green, and sure smelled like petrol.

I know different fuels have different colours, but I've never seen hi-octane petrol in that orange colour - and the new Shell got the bikes running again after flushing out the carbs.

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 17, 2020 3:49 pm
by Jeff K
A couple of years ago my dad filled up the gas tank in his 4 wheeler at the cabin from a gas can full of older gas. He did not run it for a couple of days. Then he started it, it idled ok, but would died out and it ran rough. He loaded it up on his trailer and dropped it off at the dealer for a tune up. Next day he loaded it up from the dealer and brought it home. He unloaded it and it ran ok. It sat for a couple of days and then when he started it up, same old problems. He loaded on his trailer and brought it over to me. We unloaded it and it ran great.
I knew right away what the problem was. We parked it and it sat over night, next morning started right up and then had the same problems. I let it sit for a hours and drained some gas from the carburetor in to a white plastic bowl. --- There it was, water drops on the bottom. We have gas here in the USA that has 10% ethanol added to it. It goes flat very fast. But the worst problem is that alcohol is hydroscopic and it absorbs moisture from the air. So the longer it sits, the more moisture. And here is another problem, that is the gas can absorb more water then it can hold in suspension. So if you shake it up, like towing it on a trailer, the water will be temporary suspended. But once it sits for a while it will fall out of suspension and sink to the bottom. Once at the bottom the water is more the happy to plug your main jets.
Jeff

Re: Mystery problem and BP is to blame!

Posted: Mon Feb 17, 2020 11:36 pm
by kommando
You can bring old petrol back to life by adding toluene, cheap thinners contains a lot. So each spring I dose all the petrol tanks with thinners 10 mins before I open the tap to the carb. Does not solve the water issue though.

Re: Mystery problem and BP is to blame!

Posted: Wed Feb 19, 2020 4:17 pm
by hhh
Jeff K wrote:
Mon Feb 17, 2020 3:49 pm
...alcohol is hydroscopic and it absorbs moisture from the air...
The word you want is "hygroscopic." You can ameliorate this by adding methyl hydrate to your gas.

Re: Mystery problem and BP is to blame!

Posted: Thu Feb 20, 2020 5:20 am
by BSA_WM20
The dye that goes in the fuel does not evaporate.
The fuel does so as it gets staler it gets darker.
It is designed to do this so those who are in the know can see it is ( or has ) gone off.
Some times it gets pumped out & sent back for reprocessing other times the servo will do a discount till it is all gone.

As for adding toluene down here the fuel can be up to 40% by volume toluene to start with.
It can also be 30 % strait Benzene or 25 % methyl benzene but no more than 40% combined benzines ( and there are dozens of them ).
Usually a no start stale fuel can be fixed in a pinch by adding around 1% acetone but better to tip it out as the thick mixes can cause build up & fouling of the plug .

Re: Mystery problem and BP is to blame!

Posted: Thu Feb 20, 2020 2:51 pm
by Jeff K
hhh wrote:
Wed Feb 19, 2020 4:17 pm
Jeff K wrote:
Mon Feb 17, 2020 3:49 pm
...alcohol is hydroscopic and it absorbs moisture from the air...
The word you want is "hygroscopic." You can ameliorate this by adding methyl hydrate to your gas.
Methyl Hydrate also known as Methanol, aka Methyl Alcohol. I did exactly that years ago when my old VW van got a tank of bad gas at a fill up on the way to work. We used Methanol at work, so I had access to lab grade and lots of it. I barely made it home after work and had to drain the gas tank. The Gas Station had to admit that they had a bad batch of gas that had gotten contaminated with water. Our gas has and had at the time 10% Ethanol in it by law, add excess water and then add Methanol and it did not play nice with the fuel injectors. A lot of times you can tell by the smell of gas if it is good or not, if it has no smell or smells like paint thiner, then it is getting old.
Jeff