Petrol Fountain!

[eagle747]

Hi! New to the forum and I have a problem I think others have experienced.

After a major rebuild I have petrol being pumped out of the exhausts - nearly set my workshop alight!

So the carbs have now been stripped and cleaned, float levels checked and the floats and needles inspected. All back together but the problem is still the same - a LOT of petrol shooting out of the exhausts. It looks like two carbs are at fault here.

So two questions:
1. Can the rubber tips on the float needles dry out and shrink? Would soaking them in petrol help?
2. Is there any mechanism to prevent the fuel pump 'over pumping' and flooding the engine - like a fuel pressure sensor? Can't find anything in the manuals.

PS my Vmax is a '97 49-State import with about 30,000 miles on the clock.

Thanks
Mark from Cornwall (UK)

 

[06VMAXIMUS]

Mark, welcome to the VMF! I would think either the needles or seats need replaced. Also check for fuel absorption in the floats....it rarely happens, but sometimes it does. You can weigh them individually and compare results. Good luck!

 

[eagle747]

Thanks for that. Actually the solution was a bit unexpected. The guy who was doing most of the rebuild for me had joined two carb breather pipes together at the spigot / bracket that sits up near the airbox. So the two right hand cvarbs could not breather - so the fuel pump was pumping fuel right in through the main jet. I found it when we were checking for breather blockages.

She is now running like a sweet thing!

 

[johnpclynch]

When you say "out of the exhausts" do you mean at the back of the bike :ummm:

OR out the carb bowl vent tubes (attached to the airbox)

If it's pumping out of your carb vent tubes then the valve attached to the float inside your carb isn't closing when the bowl is full and your pump won't stop until your tank is empty

As mentioned above this can be caused by the valve seat being worn or a punctured float, another option is that there's some grit holding the valve open or your carbs weren't assembled properly (small clip on the float valve not connected to the float bowl)

I hope it's an easy fix for you

 

[eagle747]

Not exactly. Fuel coming out of both silencers. Cos the breathers from the carbs were misconnected (too each other) the fuel was flooding into the engine. Didn't need to touch the float bowls etc. - apparently a blocked breather causes the 'fountain' effect (fuel was coming out the tops of the carbs too! They were effectively blocked cos they were joined together - just6 a stupid mistake!

 

[alorio1]

Good find, but also a bad mistake by the mechanic. Oh well we learn by mistakes and maybe this will help someone else who thought your mechanics idea was good. Thanks for sharing info with us......

 

[eagle747]

Yeah - he also managed to drop a camshaft cap dowel down a spark plug hole and set the rear cylinder camshafts up with the front cylinder timing marks! Beginning to think I should have done it all myself! I did get a lot of useful advice (and components) from Exactrep - can't praise them enough!

 

[MaxMidnight]

Perhaps a different mechanic is in order?

If you ask around on V Max Chat, there may well be someone local who would be willing to give assistance.

 

[eagle747]

Thanks Steve - but at least this time I've sorted it. Spent way too much money - but have plans for stuff later in the year like USD forks - so will be pestering then!