Fuel Pump Rapid Ticking

[radioactiveman]

Hello

Today I took the old boy out for a bit of a run.

I noticed I was pretty low on fuel so I set off to the petrol station. I filled up with new, premium fuel and off I went.

I immediately noticed my fuel pump was ticking rapidly as I set off. This continued for the rest of my journey, sporadically.

The car seemed to run relatively well the rest of the time. It didn’t stutter or kangaroo or anything like that.

When I got back to the garage I popped bonnet to see if anything looked obviously wrong and the behaviour continued. When it wasn’t misbehaving it seemed to tick once every 2 seconds or so at idle.

I have in the past fitted a new float and needle as my float bowl overflowethed.

Any ideas? Or is it time to call the scrap metal man?

[radioactiveman]

After a lot of reading around the internet this sounds a lot like the symptoms of fuel vapourising. It occurred to me that this is the first time I’ve used Texaco rather than Shell for my Morris fuel, and I’ve realised that the RON ratings are different (97 vs 99) for their premium products.

I wonder if the different fuels could be enough to cause the fuel to vapourise intermittently? It does seem odd/unlikely that the engine is that sensitive

[philthehill]

It could be fuel vaporisation and it is not an unknown fault with Morris Minors.
To reduce the possibility of fuel vaporisation a kit was produced by Mr Grumpy to deflect heat away from the fuel inlet pipe and the float chamber.
The heat deflection kits are available from ESM.
https://www.morrisminorspares.com/fuel- ... ly-p830677
Or you could make your own!

[jaekl]

Try again when the car is cool such as first thing in the morning. If it is just fuel vapourisation, then all will be fine at those temps. Typically, vapourisation happens in the vertical run up to the pump. This is the point of lowest pressure, which is less than atmospheric. Whereas the fuel from pump to fuel bowl is 3psi above atmospheric. The increase in fuel temperature is not as great as the increase in pressure. The fuel from bowl to carb, may vapourise, but shouldn't cause the pump to be constantly pumping. Constant pump is either an air leak or the pump is trying to pump vapour which the more it pumps, the lower the fuel pressure, and thus more vapour. In this case an air leak is not likely. I would lean towards a restriction in the fuel line inlet causing the pump to pull the line pressure down very low. Try blowing air into the fuel line at the pump to clear the line to the pump. With modern cars with high pressure fuel injection systems, the fuel you filled the tank with may be formulated differently and is more prone to vapourization in system like ours. The problem may just be the fuel selected.

I typically encounter vapourisation on a warm day with winter formulated fuel still in the tank. I found fuel vapourization is worst when idling after a run when the temps are the highest and there is no air flow. The engine may stall at this point and it's best to wait until the pump is satisfied before trying to restart. Once driving again, there will be an occasional short periods of rapid pumping. You report constant pumping, which is why I lean toward a line restriction.

[radioactiveman]

Thank you for your responses!

The symptoms seemed to be just after I’d pulled away generally, but went away when was up to moderate speeds. It also didn’t seemed to impact the running of the car just a short spell of furious clicking and then back to normal clicking.

When I got back to the garage it seemed to idle fine (as fine as it ever does ). Maybe the occasional couple of fast clicks but certainly not constant.

I wonder if filling up swirled up some crud in the tank, which could have blocked something.

[jaekl]

That behavior is more like fuel line to the pump vapourisation. How warm was the day?

[panky]

My traveller used to click and tap like a woodpecker in traffic. After it's restoration with a completely clean system and new pump I was, for the fist time since the rebuild, stuck in traffic for about an hour. After about three quarters of an hour the manic avian re-appeared tapping and knocking away but as soon as we were moving again and a higher flow of fuel passed through the system all was calm again. I often wondered if a 12v computer cooling fan directing cooler air onto the carb/pump would do any good in this situation.

[radioactiveman]

That behavior is more like fuel line to the pump vapourisation. How warm was the day?

It was yesterday in SW London, so it must have been less than 20 degrees. Certainly not scorching!

[jaekl]

As Panky mentioned, the return to normal pumping while moving is indicative of vapourisation. A restriction would just be worse when the fuel demand increases. The fuel most likely is formulated for fuel injection systems.

[radioactiveman]

Thanks, everyone!

I can't believe using a different fuel brand would make such a big difference, but it does seem to fit Guess I'll be avoiding Texaco from now on

[oliver90owner]

Hafta remember that most modern vehicles the fuel systems operate under pressure - often from a pump in the fuel tank. Texaco may well be including more lower carbon chain ‘anes’ so that, under partial vacuum and with moderate temperature rise, some components in the fuel mix may well evaporate in the line.

Maybe keep it in mind to avoid texaco, if filling the lawn mower? The modern fuels go ‘off’ soon enough, without buying from those sources which will likely go ‘off’ even quicker than some others.