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Fuel pump racing, no gas

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At idle the BN4 fuel pump will click as fast as it can, but the car acts as if it is fuel starved. New in line fuel filter. Help?
Thanks!
 

LarryK

Obi Wan
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New pump? Old pump? Might have lost the flexibility in pump valves. May have hole in suction side of pump. Fast pump means it isn't filling carbs. May have hole somewhere between pump and carb. Follow line from tank forwrd. Easier if it isn't dumping on floor, would in tank or pump. Also, just talking, does tank have fuel in it or did someone steal it while garage door open.
 
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longbridgehealey
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Old pump, no leaks thinking pump. Tank full, just did itšŸ™ƒ
 

roscoe

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If all you did was put in a new filter and it was fine before that, is the filter directional, is there any sort of check valve in it? If there is and it is in backwards it possibly could cause your symptoms. Many inline fuel filters have check valves to keep pressure in fuel lines or rails and prevent vapor from forming after shutdown. Often there may be an arrow on the filter body that shows fuel direction of flow. If it were in backwards it would prevent the pump from pulling fuel from the tank and perhaps it leaks enough to allow idle because the is " pulling fuel past it" wheras normally it just would keep fuel from leaking back to the tank at almost zero pressure.
 

red57

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If the new in-line filter is between the pump and the tank, it could be a fitting leak - it's possible to have a leak that sucks in air but doesn't leak gas out.

Dave
 
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longbridgehealey
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Hi Dave, filter down line from pump. Checking filter for direction.
 

RAC68

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If I presume correctly and you installed the filter between the tank and pump, I would follow Jon and Dave's suggestions and check the direction of the filter and assure you are not sucking air through a leaking fitting. Also, if you cut the line between the tank and pump, you have severed the ground connection for the gas float sending unit. I would install a new ground line from a gas tank sending unit cap screw to a solid body ground or you may not have a gas gauge reading anymore.<br>
<br>
Ray(64BJ8P1)
 

steveg

Yoda
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...Also, if you cut the line between the tank and pump, you have severed the ground connection for the gas float sending unit. I would install a new ground line from a gas tank sending unit cap screw to a solid body ground or you may not have a gas gauge reading anymore.<br>
<br>
Ray(64BJ8P1)

Good advice for anyone.
 

blueskies

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If the filter is down stream from the pump, as it appears to be, installing the filter backwards should not cause the pump to continue clicking/running. For some reason, the pump is not building pressure. Since the fuel is not leaking out under the car or in the engine compartment, obviously, the pump is not pulling fuel from the tank. That likely means a tank or fuel line blockage upstream or a bad pump.
 
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longbridgehealey
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Ok, finally a solution. Pump failing. Replaced pump and all is well. Took an extra day to respond, we are also in the process of moving. Drove the Healey today from central FL to the Gulf Coast, our new home in Palm Harbor. Thanks to everybody for all the help!
 

madhouse

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Good info here. My BN-4 was rebuilt 2 years ago - been running great, even in hot 90 degree weather. But yesterday on a 30mile drive in 75 degree weather it had all the symptoms of vapor lock. Full tank, starving for fuel. Could restart after short stop, but not apply much demand on carbs. As soon as i did, it died. Finally I opened the hood and the took off rear seat cover (above fuel pump), let it sit for 45 min, and it ran fine for the rest of the way home. My fuel pump is only 2 years old. Could it have just been some heat in the wrong spot to vaporize fuel this time? First time its happened. I'm thinking about covering all my fuel lines with some heat resistant sleeves, maybe the fuel pump and part of carbs. is that overkill? I will also go back and look for air leaks, never saw any fuel leaks. Engine temp was within range (180degrees).
 
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My BN-4 was rebuilt 2 years ago - been running great, even in hot 90 degree weather. But yesterday on a 30mile drive in 75 degree weather it had all the symptoms of vapor lock.

IIRC, older sixes, like the BN4, had the fuel line on the same side of the exhaust (my BJ8 has its pump on the passenger side). My experience--with a BN2 and a BJ8--is that the 'vapor lock'--'cavitation,' etc.--occurs in the engine bay, esp. with the carbs sitting on the exhaust manifold (but putting a fuel pump above the exhaust pipe isn't a good idea--Geoff must have been absent that day). My guess is something is opening up somewhere between the tank and the pump--that's when you usually get a racing pump--though what it could be, I have no idea. I think the ambient temp is irrelevant (again, just a guess).

We put a (supposedly) good used tank in our BN2, and we were stumped by erratic fuel delivery until my dad cut the old pipe off the tank and found some corrosion at the joint--Dad figured it was probably from the flux used to solder the line to the tank--where there was a pinhole leak. Drove a couple fuel pumps crazy. Also, I remember an old article in 'Skinned Knuckles' where the author bought an old Caddy--I think--on the cheap because it would stumble badly at highway speeds. Eventually the author found a small dent or kink in the fuel line; when hot, the fuel would cavitate after the dent/kink and vaporize the fuel supply.
 

madhouse

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Bob Spidell,
Thanks for your response. I have done a few things based on your notes:
1) I found a few slight kinks in the steel fuel lines between the tank and fuel pump, so I cut out that section and used flex hose to the fuel pump (just another 3 inches from what was already there). unfortunately, that did not help.
2) I had a backup Facet Fuel Pump that I have been carrying with me, so I installed it on the passenger side of the car behind the footwell (consequently further away from the tail pip/muffler). I thought I had it fixed, but after then engine reached operating temp for a while (20 minutes-ish) while driving in 70degree weather - the facet pump starting clattering louder similar to the SU. I did use the rubber buffers when installing the facet and the default 'click' was well deadened at first.
3) Since I have a 4seater, I can easily check/trace the line all the way from pump to tank. I just can't see any points of leakage in the line. So i'm left with 2 more options - both of which you mentioned in your note on 5/1/2020.
a) Perhaps I have a leak in the fuel line that extends into the tank, and when the fuel level drops below that leaking point, the pump is sucking air (?). or perhaps at the joint itself at the tank. This is only a 5 year old tank, but perhaps it was delivered with these defects - I've had the problem as long as I can remember. OR
b) I need to do someheat isolation in the engine compartment, possibly with some creative use of DEI heat insulation for fuel lines and carbs.

For now, I'm going to experiment and see if the clatter starts when my fuel tank is at a certain level, rather than driven by heat. If negative on that - I may be pursing a new tank. thanks for the info.

Rob
 

DerekJ

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Check to see if the fuel tank cap is venting properly. If it isnā€™t a vacuums effect is created. You will hear a pressure hiss when removing the cap. Just a thought, it happened to me.
 

madhouse

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Thanks DerekJ. I hope it's as simple as that - I will do a bit of experimenting to see what happens. But I am using a new locking gas cap from Moss, so I suspect it is good. Will let you know.
 

blueskies

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Have you checked the seal at the fitting where it exits the tank? You may not see fuel leakage there, unless the tank is completely full or over full, even if it is sucking air. That happened to me once. Didn't know I had a problem there until I completely filled the tank, including the filler spout.
 

madhouse

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blueskies - thanks. that's a great idea. I do smell gas when I fill all the way, but just thought it was from the gas cap. I will check it out and let you know.

Rob
 

blueskies

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A gas smell when you fill the tank all the way can also come from a poor seal on the rubber sleeve on the fuel filler pipe or from a bad seal on the sending unit. The sending units can get bent around the edge, and a new seal won't work well unless the sending unit edge is carefully straightened. But that is a separate issue and would not account for the fuel pump running issue.
 

madhouse

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Derek,
I drove for about 40 miles today then checked the gas cap for the venting issue. I did not detect a vacuum effect in the tank when I removed the cap. Dang - I was hoping it was that easy! thanks for the suggestion anyway.

Rob
 
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