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 Posted: Aug 4, 2019 08:15AM
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US
If it works for you... great.  

For future reference, I cannot remember who it was but one of the MM board members from Canada used to power his electric fuel pump by tapping into the hot wire for the rear license plate light.  He considered this an anti-theft device as no one would normally use the running lights or headlights during the day.

Doug L.
 Posted: Aug 4, 2019 05:52AM
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So I couldn't help but try an unconventional solution AND IT WORKED!!

I installed brass "T" fittings, one before and one after the fuel pump.  I looped fuel line back between the two  fittings and installed a brass needle valve for flow control in the loop (as seen in the attached picture).  With the needle valve only slightly cracked there is a small amount of leakage from pump pressure into the loop.  The pump flow rate is well in excess of my engine's needs so the slight reduction in efficiency is not noticed.  If the engine is hot and I shut it off, any vapour that develops will push back to the tank through the needle valve and not into my float bowl.  I have not had a flooding situation since my modification.

I'm sure someone will chastise me for such a modification, but I did not want to fish a dedicated power line to the rear of the car and listen to the clicking of a fuel pump.  At the very least this is a cheaper and simpler solution.

Now onto the next problem...

 Posted: Jul 29, 2019 12:22PM
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Quote:
Originally Posted by biffidum
...would you have a recommended model?  
I just recently looked this up for a fellow Triumph owner.  You may want to consider the following three pumps.  Google for them by model number and shop around.  Prices vary quite a bit.

Facet Cube Pumps: 40163 1.5-2.5 PSI, or 40177 1.0-2.0 PSI 
Or 
Facet Posi-FLow Pump: 60304 1.5-2.5 PSI

The first two make a non-stop ticking that drives some people nuts.  I don't notice it when the engine is running.  The last pump is a more "quiet" design that kind of whirrs instead of ticks. 

Doug L.
 Posted: Jul 29, 2019 11:34AM
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Doug, I think you are correct.  I did stop the boiling by wrapping the fuel lines with tin foil, but this is not a permanent solution.  I found some low pressure electric pumps on Amazon, but would you have a recommended model?  I have been focusing on vane style pumps suited to carburetors.

 Posted: Jul 29, 2019 05:16AM
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You can try all sorts of experiments to stop the fuel boiling.  However, you are going to have problems as long as you have a mechanical pump that measures 200 oF.  It will be simpler and faster for you to fit a low pressure electric pump at the rear of the car and to get all the fuel line plumbing below the level of the float bowl.

Doug L.
 Posted: Jul 28, 2019 07:35PM
 Edited:  Jul 29, 2019 05:18AM
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Hard to tell on my phone but regarding the fuel overflow it looks like you have one it is the line that is resting on the servo vacuum line.


If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Jul 28, 2019 11:45AM
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Actually, after thinking about it, I think I will fit two "T's" into the fuel line one after the pump and one before the pump.. in the short bi-pass I will fit a needle valve so I can adjust the leak back.  I'm willing to bet this will solve my problem.

 Posted: Jul 28, 2019 11:34AM
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I have the fuel filter located just outside the firewall and zip tied to the hard line of the clutch master cylinder.  I then route the fuel line high behind the air filter to the other side of the carb as the inlet spigot is on the opposite side of the carb.  The carb has the standard heat shield that drops a few inches below the intake port.

I am convinced that the heat is mostly at the fuel pump.  I pointed an IR gun at the engine and it is running around 200F at the rear at shutdown.  A small thermostat controlled fan would make a difference...

I may consider an electric fuel pump.  In my simple head it would seem like a pin hole bi-pass in the mechanical fuel pump would let excess pressure from vapor just push fuel back to the fuel tank... from what I can tell the pump has far more supply capability for this little engine, that the slight reduction in efficiency would not be an issue.  I the fuel line is looped above the bowl it would not drain completely back... but drain back could be an issue.

Maybe an electric fuel pump that is not an absolute positive displacement type... like a gear pump style.. would let excess pressure backfeed to the tank...

 Posted: Jul 28, 2019 09:38AM
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Please verify terminology.  

Fuel boiling in a line, filter, or carb “downstream” of the pump might cause fuel to push through the  carb float or jet, thus causing flooding. 
Most reading I have done suggests that vapor lock is entirely different. It is a problem “upstream” of the pump, meaning the suction side, thus the pump losing prime. (A non -hot , non- car water pump will do the same until it can has restoration of liquid medium to work with)  

For a mini with a mechanical fuel pump in its stock position, that means low , thus near the exhaust system which of course is much hotter than the engine. If this the case then fuel boiling up by the carb where temp is , say, 200F, is a different issue than down low by the exhaust where temps are much hotter and a nearby fuel line is at more thermal risk and different risk. 

These comments are meant from a scientific perspective and so knowledgeable comments are requested and appreciated .

 Posted: Jul 28, 2019 09:03AM
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FWIW, this has been happening to me for 10 years. I've raced multiple A-series powered cars in 24 Hours of Lemons and nearly every time we have to refuel and switch drivers, the fuel is boiling and causing starting difficulties. The solution for us depends on the car and it's particular characteristics. But by-and-large it is foot to floor to open throttle and remove some vacuum / give it as much air as possible and crank til it starts to catch then manipulate throttle as necessary to keep it running until you clear it out and then drive away.

With a turbo it was far, far worse. A thin piece of tin as shielding did help quite a bit when we've run that.

But yea, it's a bit unnerving watching your fuel boil, or worse, hearing it boil in the carb. (All of my Lemons A-series have run HIF carbs)

 Posted: Jul 28, 2019 04:41AM
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Thank you for all the suggestions.  I am away camping and will post back after I try a couple of things when I return

 Posted: Jul 27, 2019 07:35AM
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GB

There was a couple of article in Mini World about a decade ago where a car was put in a wind tunnel, and the results were fascinating.

Raising the rear of the bonnet only works for heat removal when stationary - on the move it is theoretically counterproductive due the the surprisingly high pressure area at the bottom the windscreen.  

The heat shield on an HIF44 will prevent radiated vapourisation where the HS4 float bowl is expose to the manifold heat.

I put a float bowl extension on Gertie's HIF44 and have suffered from hot running vapour locks ever since - I've subsequently realised that the extension is low the level of the abutment heat shield...

 Posted: Jul 27, 2019 05:04AM
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Oddly enough, with my 998 running a mech. fuel pump and a single HS4, every time I stopped on a hot day it would vapor loc. My solution was to open the bonnet as soon as I got out. Not even fully open just pop it and let it stand on the spring. Come back and all was well. When I replaced it with a Cooper S unit I went to HIF44 and electric fuel pump. I have not had the issue since. I do slide plug wire heat shield tubing over the exposed fuel lines under the bonnet. It was suggested to me I remove the rubber seal across the rear edge of bonnet and adjust the rear edge high enough to allow heat to escape. Steve (CTR)

 Posted: Jul 27, 2019 01:37AM
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GB

Where is the fuel filter ?

If it's close enough to the manifold that radiated heat is boiling the petrol it is very much in the wrong place !

The usual place to put one is either at the back between the tank outlet and the front/rear fuel pipe or on the bulkhead where the fuel pipe pops up behind the subframe - both positions are cool and shouldn't incur vapourisation.

If you could post a photo or two of your setup we'd all be in a better place to see and advise.

 Posted: Jul 26, 2019 01:59PM
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The HIF44 I have on my Traveller has a float bowl overflow.

 Posted: Jul 26, 2019 12:32PM
 Edited:  Jul 26, 2019 02:53PM
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Other owners have run LCB headers with HIF's with no issues so unless the carb venting has something to do with it i can only think that the fuel lines are too close to the header.
Maybe you can run a new metal fuel line from the pump away from the header. Years ago i owned a Mini that i made up some fuel line from brake line tubing re routing it to where it was away from the header.


If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Jul 26, 2019 10:54AM
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Yes, there is a heat shield fitted to the carb.  The boiling is originating at the fuel pump as it sinks heat from the engine.

I have a LCB header.  I can’t attach a photo with my phone so that will have to wait.

It does seem odd that there is no overflow port from the bowl.  Could always drill one

I was told to run premium as it has no alcohol in it and has a slightly higher boiling point.

 Posted: Jul 26, 2019 10:10AM
 Edited:  Jul 26, 2019 02:53PM
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Quote:
Originally Posted by biffidum
I finally got my mini on the road.  As I slowly work through the quirks, I have come across a minor annoyance.  I am getting heat soak from the engine after driving and at full temp... this is causing the fuel to boil in the fuel line after shut off and the pressure is pushing past the float needle and flooding the car out.  I can start it, but I have to turn over for 15 seconds and rev it up to clear the fuel, then all is normal.

I know the fuel is boiling because I can see it bubbling in my glass fuel filter.

I do not want to drill holes and install a pressure regulator and return line to the tank - I know this would solve my problem.

I am hoping someone has a magical sweet spot to route the fuel line or perhaps an added length of hose, a loop, or some special fuel filter combo that will minimize this effect.

The engine description is in my profile.  I have swapped in a large (2" diameter) plastic Kohler fuel filter and it is slightly better as an air bubble seems to absorb some of the pressure.

The thermostat seems to keep the engine at a steady 190F... never overheated.

I don't relish the idea of taking the carb off for the 100th time and checking the float valve...(it's new).
I do not own a pressure meter to see just how high the pressure is getting, but it is safe to say that once boiling it is likely fairly high.
Also, my HIF carb does not have an overflow barb where I would expect one... the casting is solid at this point (on both sides).

Any thoughts are appreciated ...

--- I can't see my profile so:
1275 A+
HIF
mechanical fuel pump
Assuming that this is not a factory set up a picture of your carb and the fuel line routing may help.
Do you have a heat shield fitted?
What type of exhaust header are you using?
There must be some kind of vent for the fuel chamber otherwise it would not run.
Maybe your HIF is not a correct Mini one.


If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: Jul 26, 2019 07:51AM
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I offer my suggestions below. 

You mentioned not wanting to add a fuel pressure regulator since you didn't want to run a return line.  To the best of my knowledge, only injection regulators route fuel back to the tank.  Since regulators for carb engines do not have a return line it is unlikely that a regulator will help.  

Set your float level a little bit low.

But most importantly....  Take all your fuel lines feeding the carb and do whatever you have to so they (and your fuel filter(s)) are kept below the HIF float bowl.  Fuel in the lines and filters that is above the float bowl has nowhere to go except past the float valve and out the jet.

Doug L.
 Posted: Jul 26, 2019 06:52AM
 Edited:  Jul 26, 2019 07:03AM
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I finally got my mini on the road.  As I slowly work through the quirks, I have come across a minor annoyance.  I am getting heat soak from the engine after driving and at full temp... this is causing the fuel to boil in the fuel line after shut off and the pressure is pushing past the float needle and flooding the car out.  I can start it, but I have to turn over for 15 seconds and rev it up to clear the fuel, then all is normal.

I know the fuel is boiling because I can see it bubbling in my glass fuel filter.

I do not want to drill holes and install a pressure regulator and return line to the tank - I know this would solve my problem.

I am hoping someone has a magical sweet spot to route the fuel line or perhaps an added length of hose, a loop, or some special fuel filter combo that will minimize this effect.

The engine description is in my profile.  I have swapped in a large (2" diameter) plastic Kohler fuel filter and it is slightly better as an air bubble seems to absorb some of the pressure.

The thermostat seems to keep the engine at a steady 190F... never overheated.

I don't relish the idea of taking the carb off for the 100th time and checking the float valve...(it's new).
I do not own a pressure meter to see just how high the pressure is getting, but it is safe to say that once boiling it is likely fairly high.
Also, my HIF carb does not have an overflow barb where I would expect one... the casting is solid at this point (on both sides).

Any thoughts are appreciated ...

--- I can't see my profile so:
1275 A+
HIF
mechanical fuel pump