Fuel pump going mad

[DaveW]

Hi all
Advice please.
Had a fairly strenuous stop/start drive this morning in the lovely ( hot) weather for about three hours.
Fuel pump fluctuated between its usual regular ticking and sounding like a mini machine gun. Didn't seem to matter whether pottering slowly or accelerating hard.
No fuel leaks or smell of fuel. No misfires, car ran perfectly.
Is this normal? Haven't heard it before but haven't driven it hot weather much last year. I wondered if fuel was vapourising slightly and the pump was pushing vapour and not liquid. Inline filter looked normal.
Original factory pump.
Thanks all.

[svenedin]

Absolutely classic fuel vaporisation. Buy the Grumpy kit of rising fuel pipe heat shield and float bowl heat shield from ESM and you will never have the problem again.

Stephen

[DaveW]

Thanks Stephen

[svenedin]

You’re welcome. I am in France now with my Minor and it’s considerably over 30 C. With the heat shields fitted the fuel vaporisation is not an issue in the slightest. It was a severe problem previously in very hot weather stuck in traffic jams.

Stephen

[stuffedpike20]

I have got the heat shields fitted, and I still get the machine gun occasionally.
Is there anything else that can be done?

[geoberni]

I had the same problem for a short while around 5pm, on my way home from the Sandringham event, undoubtedly the hottest part of the homeward journey.

My first thought was the dreaded 'Fuel Vaporisation' which I've never experienced before, but it was only while I was doing around 55-60 and the Temp gauge I have fitted was getting quite high, at about 7/8ths the way up to the Red Mark (the gauge is just one of those with C-N-H markings).
Cutting the speed down a little fixed the hesitancy and slowed the rapid pump clicking but not eliminating it.
I pulled over for a look and them was some dampness on the shelf under the pump.
I continued home without problem, keeping the temp gauge nearer the 'N' with speed in the 45-50 range.
When I got home, the pump was still chattering though not at teletype speeds.
I took the pipe off the carb and pumped about a mugful of fuel out into a container, with the pump clicking normally.
I used my Temperature Gun to check the temp of the fuel I had just pumped out and it was approx 35 C. So I'm guessing that was close enough to ambient temp.
I reconnected the hose and with Ign on, no clicks from the pump as the carburettor reservoir was presumably full.
The damp mark was not any larger but the exterior of the pump was a little damp when wiped over with some blue paper towel.
Car happily drove into the garage for the night and I'm going to be looking at the pump this morning.

At the moment I'm suspecting the high temps resulted in a leak at the pump sucking air in while allowing some drips of fuel to escape.

I shall report back...

Well as nobody has posted anything else, I can still get to edit this.
.

20260525_120837.jpg (1.53 MiB) Viewed 2886 times

When I refurbished this pump a few years back, I gave the lower casing a coat of silver colour paint.
It's clear that the connections have wept, as it's lifted the paint.
I was able to get about another 45 deg of tightening up on both the fittings, slightly more on the output than the input.
I then switched Ign on to check it and it clicked normally.
Switching back off, I cracked the outlet elbow connection just enough to realign the fitting and pipe and re-tightened.
Checking the pump again and clicked quite rapidly, so I repeated the action I took last night of pumping a little fuel into a container and then refitted the pipe to the Carb.
Pump now clicking at expected rate.

It just goes to show that the smallest amount of air can cause the pump to clatter away.
I could probably have cleared the rapid clicking just by starting the car and moving the air that way, but I saw no need to burning off fuel just for that.

As there was a leak, I'm going to go with that as the cause of my engine hesitancy, unless it happens again.

[stuffedpike20]

Good post berni.
I checked mine today, and was able to tighten the outlet union by about one flat.

Hopefully no more machine gun.