[Healeys] Fuel pumps (AGAIN!)

[Bob Spidell]

Any idea what brand sealant was used?  The BH product has very specific 
application instructions involving a cleaner and an etching compound 
before the sealant is applied.  Like any 'paint,' the job is 90% 
preparation.  IIRC, both of my tanks were new or near-new when we 
applied the sealant.

On 12/1/2018 7:01 AM, warthodson at aol.com wrote:
> Another sloshing horror story. We were 600 mikes from home & in the 
> Rocky Mountains. A friend's 3000 had been running fine until one day 
> in the mountains. It began to run fine for about 15-20 minutes, then 
> slowly die. A few minutes later it would restart & run fine for 15-20 
> minutes & die again. It repeated this pattern over & over. Of course 
> we checked adjusted &/or replaced everything we could. The problem 
> turned out to be the sloshing sealer that had separated in a large 
> sheet from the bottom of the tank. With the pump running the sheet 
> would be sucked up to the pickup & the pump was being starved for 
> fuel. When the engine died & the ignition was shut off the sheet of 
> sealant would slowly sink back down to the bottom of the tank & the 
> pump could again deliver fuel until the sheet was again drawn up to 
> the pick up.
> Gary Hodson
>
>
> -----Original Message-----
> From: Bob Spidell <bspidell at comcast.net>
> To: healeys <healeys at autox.team.net>
> Sent: Fri, Nov 30, 2018 10:47 pm
> Subject: Re: [Healeys] Fuel pumps (AGAIN!)
>
> Moah DATA!  Yeah!
> Definitely makes sense.  Both my Healeys have had their tanks sloshed 
> with Bill Hirsch sealer (I heard Bill Hirsch died recently, BTW).  The 
> BJ8's tank was done at least 20 years ago, the BN2's more recently.  I 
> inspect them occasionally and have seen no evidence of any fragments 
> of the sealer either coming out of the feed pipe or in the pumps when 
> I pull them apart.  Also, when the last pump stopped and I fitted my 
> last spare pump it started pumping enthusiastically--and I drove it 
> for 10 or so miles--so if the pickup tube in the tank is plugged I 
> wouldn't expect that, but I'll have a look inside the tanks.
> I've reported it before, but when restoring the BN2 we bought a used 
> tank.  We had an issues with an extremely erratic pump: no pumping, 
> heavy thrashing (like fibrillation you get when the tank runs dry or 
> you have an inlet leak) and occasionally, normal pumping. We blew out 
> the lines, tried several needle valves and Grose jets but to no 
> avail.  Finally, my dad had a hunch and cut the pickup tube out of the 
> tank.  Sure enough, there was a lot of corrosion and a pinhole leak in 
> the tube near where it exited the tank.  Dad speculated that the flux 
> used to solder the tube in the tank was corrosive and not cleaned off 
> correctly (well, it was a 40-year-old tank at the time).  Something to 
> put in the diagnostics database.
> Bob
> On 11/28/2018 8:26 PM, Michael Salter wrote:
> This discussion about fuel pumps has revived something from the old 
> grey matter ...
> To those mentioning repeated failures one problem that will cause 
> premature failure is restrictions in the supply to the pump.
> The way these pumps work is that the spring in the pump provides the 
> pressure. As the pressure on the output side of the pump decreases the 
> diaphragm moves down to a point where the points close, that energizes 
> the coil to pull the armature up against the spring pressure to the 
> point where the points "flip" and open to stop the current flow 
> through the coil.
> HOWEVER if there is a restriction in the fuel line feeding the pump 
> the low pressure at the pump inlet can create a partial vacuum which 
> will prevent the armature from rising fully and thus the points from 
> "flipping" .
> When this happens the coil remains energized and "cooks" in a short 
> time thus ruining the pump.
> I discovered this while trying to resolve a delivery problem in a car 
> that had had the tank "sloshed". The sloshing compound had coated the 
> gauze filter  inside the tank severly restricting the flow.
> The test was to put an analogue ammeter on the pump electrical supply 
> which showed the prolonged current flow to the pump.
>
> M
>
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