Mechanical v Electric fuel pump?

[DODD]

I agree with Roger on all points. As noted in one of my previous posts when my SU stopped working, as a temporary measure I fitted a Facet pump. It did the job but I disliked the noise it produced, despite the insulating and sound proofing I did during its installation.

David W: have you checked the petrol supply pipe to the carburettor which runs along the chassis? The location of the fuel pipe is conveniently situated for it to be trapped by an unsuspecting mechanic when jacking up the car.

Irrespective of what pressure you have in the pump, the flow will be reduced if the pipe has been squashed or deformed.

Brian

[dwomby]

Originally Posted by DODD

I agree with Roger on all points. As noted in one of my previous posts when my SU stopped working, as a temporary measure I fitted a Facet pump. It did the job but I disliked the noise it produced, despite the insulating and sound proofing I did during its installation.

David W: have you checked the petrol supply pipe to the carburettor which runs along the chassis? The location of the fuel pipe is conveniently situated for it to be trapped by an unsuspecting mechanic when jacking up the car.

Irrespective of what pressure you have in the pump, the flow will be reduced if the pipe has been squashed or deformed.

Brian

I have the car on stands at the moment, so I will take the opportunity to inspect the full length of the fuel supply pipe. Thanks.

I really hope to get this car back on its tyres by the end of the week even if I don't do all the little jobs that I had planned while it was on stands. This time of year is best for driving fun here in Florida!

David

[roybatute]

An electric pump will keep running as long as it has power even if the engine has stopped because the fuel line has ruptured...

[dwomby]

Originally Posted by roybatute

An electric pump will keep running as long as it has power even if the engine has stopped because the fuel line has ruptured...

True but there are a couple of preventative systems: you can fit an oil pressure switch that cuts power to the pump if there's no oil pressure; and, you can install an inertia cutoff switch that cuts power if the car experiences an impact. I have the latter installed but plan adding the oil pressure switch at next oil change.

I don't think any car with an electric pump can be considered safe without at least one of those cutoffs installed.

David

[David C]

That's an interesting idea but needs some refinement. If you just use a pressure switch then you will get no fuel until you crank long enough to build oil pressure. A less ideal solution than a mechanical pump.

[dwomby]

I agree reverting to the original mechanical pump has advantages but to fit one back in my car now would be a big job and I want it on the road. I'll add it to my list of future 'improvements'.

David

[Kevin H]

I've had a Carter fitted in the boot of my 411. It makes enough noise so you can hear it fill the carb when you turn the ignition on, but once the engine is running you can't hear it. However, they seem to be unreliable and don't like being unused for long periods of time. My first one seized and just got hot - not ideal for a petrol pump, and it's replacement doesn't appear to working properly either. So I can't recommend them.

As for pressure, I don't know what the 313/318 engines need, but the 411 needs 5-5.5 PSI; I have a pressure regulator mounted inline next the carburettor unfortunately I can't tell you what flow rate is required.

As an aside, I once saw a 412 which was fitted with an electric pump which was used just to prime the carburettor before starting by pressing a button in the cabin, but still used the mechanical pump when running.