I am leaking fuel.

It is not a constant leak. When I am at work the car sits for about 8 hours straight and not a drop (sometimes a little, but not often). I go home and park the car in the garage. When I wake up the house smells like fuel. I go out and there is about a pint of fuel that has leaked out on the garage floor. I check the lines and there is nothing still dripping. The leak is coming from the Left side somewhere as the puddle is always on that side.

Any ideas as to how or why? I would say it was a fitting or bad fuel line if it was consistent, but where it's not, it is hard to find and not making a whole lot of sense.

 

I am thinking maybe a stuck fuel float in the carb?

 

suggestion

put a short description of your car in your signature or describe parts significant to the question when you ask. I for one don't remember the details of everyone's car .... I don't remember all the details of MY car! I think you have an 850 with a single SU - pretty much stock under the bonnet????

Are you still running the original type mechanical fuel pump? It looks like a flying saucer on the back left (US driver side) of the block about 3 inches in diameter and has two fuel lines connected to the top - one comes from the fuel tank and the other goes to the carb.

When I got my car home and parked it in the garage the first nite I too discovered a strong smell of fuel that I'd not noticed on the way home when the car would be parked outside - ditto the previous owner had it parked outside. The fuel that leaked when the car sat outside simply evaporated and disappeared with the breese. Chasing the leak I found that when I'd shut the car off and the system was still holding a bit of pressure the pump was leaking all around the rim. The carb sits higher than the fuel pump and when the fuel was no longer getting into the carb it was dripping out of the pump until the line was empty. The next start required cranking until the pump refilled the line and so repeated the cycle. With the car running it is so hot near the pump that what ever drip there was - was turning into fumes - a VERY bad situation btw. Not far from boom . . .

The mechanical pump has a rebuilt kit if you have an older one that comes apart but it is easier to just buy the replacement which is a non-rebuildable but same fit and function. You can get one for anywhere from $50 to well over $100 depending on if it is genuine SU or an aftermarket, and your supplier of choice. This from Seven is an example and not a recommendation altho I have ordered plenty from them.
http://www.7ent.com/detail.cfm?pageid=2060

The replacement is not difficult except for the location on the back of the block which puts you right against the firewall. Unless you decide to remove the exhaust manifold you are working in very tight quarts. I couldn't even get a socket or a standard box wrench in there and ended up with a very short throw ratcheting box. If you are doing this you may want to think about checking the condition of the fuel lines while you are at it . . . and the stock setup does not have a fuel filter anywhere so you might think about adding one of those too.

If this is the source of the drip or in ANY case a fuel leak on a Mini is very very serious. The standard fuel pump is right near the exhaust header and the carb just above it. Fuel and hot exhaust manifolds are a very very bad combination. I parked my car until I got this problem sorted out. AND I found a place to mount a fire extinguisher within reach of the driver seat . . .

If this is your problem - leaking fuel pump - you can also decide to replace the mechanical pump with an electric. If you do that yu'll need the blanking plate made to seal the hole where the mechancial pump shaft would normally penetrate the block
http://www.7ent.com/detail.cfm?pageid=2354

 

^Thank you for the suggestion and advice.

Here is the only picture I have of the set up currently:


I will open it up today and get more pictures and inspect these areas.

 

Yes mechanical pump, currently looks dry.

 

more to think about

The top of the fuel tank actually is higher then the mechanical pump and its associated connections. If there is a leak at the pump, and the tank is full, fuel is going to leak until the level in the tank drops to the level of the pump/leak .... physics in action.

Keep this in mind if you begin to work in this area. if the tank is full and you disconnect a line then be prepared for a free flow of fuel. If the tank is below this level everything is going to look dry unless the car is running and the pump is making the fuel flow.

If you need to work on this system when the tank is full, jacking the front of the car can raise the pump enuf to overcome the effects of gravity and physics in this case.

A wooden golf tee can be an ideal rubber hose stopper!

 

yes, just had that problem a few months ago on my 77 998....new pump fixed it without issues.......

 

Thank you for all of the tips. I wish I could see some moisture on or around the pump.

Roughly how much fuel were you dumping do you think?

 

have you run the motor and watched the pump? If the pump is leaking you should see it get wet pretty fast.

I doubt I even lost 'much' fuel, but it doesn't take much spilled fuel in a confined space like a garage to cause major issues and smell like something major. It also does not require much concentration in the air and the spark from a water heater or furnace pilot light to blow the whole place up.

But if you have a leaking line at the pump intake, you will drain a full tank down to that level and that could be a significant amount . . . a pint? I dunno... maybe more. In any case TOO TOO much.

In your pic of the fuel pump I can see extra joints and couplings in the line from the pump to the carb. Any of these clamps could be a source of the leak. Your gonna have to run the car CAREFULLY to find the drip probably. Do this outside with a helper and have an extinguisher handy.

I'll say this: if fuel is dripping from the pump it is probably just falling on the ground because the exhaust manifold is above the pump and while dangerous nothing bad has happened yet and may not ever. But if your leak IS at the carb, that's above the manifold and there is enuf heat there to ignite fuel and that's a big problem. If the leak is in the line from the pump to the carb, that line runs above the manifold and exhaust and that too is a bad place for a drip. You don't want fuel dripping on those hot pipes. YIKES.

If there was really a pint of gas on the floor it had to come from the gas tank cuz the entire system from the pump to the carb doesn't hold anything near that. A full tank and a leaking pump on the input side, or a leaking line on the input side, will drain the tank down to the level of the leak . . . that is the only way I can see actually getting a pint - 2 cups, 16 ounces - more than a soda can or a beer bottle - on the floor. And how long did that sit there? How much turned into fumes????

 

^thank you, all very good points.

I will have a look at the system tonight/ tomorrow and get this taken care of. Wouldn't want to have to throw a honda engine in there I kid I kid, I would never think of it.

 

Those sad old green hose clamps. On our old Minis we made a point to replace them with the screw types.

Fuel line hoses we replaced periodically as it would dry up.

On our '79 MGB we just had to do that, replace the fuel hose.

When we were younger, and just starting out on cars, we thought we could use vacuum hose for fuel line hose. Geez, what a mess we would make.

....Les

 

btw .. on the picture looking down at the fuel pump

what the bleep is that spring? What's the bottom end connected to?

 

Appears to be connected to a bracket of some sort at the bottom. Probably the throttle return spring.

....Les

 

yes, probably a throttle return spring

but I've never seen a factory diagram that showed such a thing.

looking at his picture it appears there is one on the clutch too . . .

so if the linkage don't return properly, lets find a place to attach a spring????



hmmmmmmmm

 

Ya know......when you look at the picture you referred to......does that seam look darker than it should....like it may be wet/moist?

....Les

 

IMHO the most probable point for the leak unless it is a simple clamp issue . . .

the color could just be crud tho . . . this ain't exactly a show quality engine (nor is mine)

 

Those screw clamps (don't know the official name) don't provide even pressure all the way around. That's what was causing my fuel leaks a while back. Like BJ, I wouldn't be surprised if it was a clamp. I replaced all mine with some inexpensive spring clamps and haven't had any issues since.

 

I prefer screw type clamps and typically pull all the one time use spring clams and replace with good quality screw type ... but different strokes and all that . . . any clamp improperly applied can become a problem. I find some spring clamps don't close well if opened too far or too many times.

Just what I prefer and what works for me .... not a condemnation of the other.

 

I did find some screw clamps that were designed to give pressure all the way around, but unfortunately not sized for the Mini's fuel lines. And I was in no mood to continue shopping around, after having made three trips to the auto parts store in one day. Otherwise that's probably what I would have gone with.

 

update?

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