Electronic Fuel Pump

[Gary RH7]

Well just gone and ordered a fuel pump after thinking about it for years.
If I dont start the old Triumph for a while the fuel drops down the pipe and it takes an age for the mechanical pump to get the fuel back up to the carbs.

Question is, as I have not seen the installation instructions yet, shall I bypass the mechanical pump or keep it in line?

I am inclined to keep it in line as the design is, the faster the engine goes the faster the pump will go and supply fuel at the designed rate.

Any views?

[peterw]

Personally i would by pass and then remove the mech pump and blank off the hole, the electric pump should pump plenty unless you are sucking gallons per minute like me. 

[damouk]

I'd remove it, less plumbing and joints to fail, the electric pump will have more than enough umph

[Brandy Barrel]

Don't forget to mount the pump vertically so it works better.
The mechanical pump will wear rapidly if running dry without fuel. This will increase friction and absorb power, also taking it off compensates for the weight being added with the new pump.

[Iancider]

Gary,

Is your car normally aspirated or injected?  If it is injected you need a fuel rail, return fuel line and pressure regulator to fee the injectors properly.  I would definitely remove the remove the mechanical pump or it will potentially restrict the flow and you would not gain from the new pump.

Ian

[Gary RH7]

Gary,

Is your car normally aspirated or injected?  If it is injected you need a fuel rail, return fuel line and pressure regulator to fee the injectors properly.  I would definitely remove the remove the mechanical pump or it will potentially restrict the flow and you would not gain from the new pump.

Ian

Ian,

It is normally aspirated. Bog standard Triumph twin carb.

Looks like the general opinion is to remove it. Luckily I have a gasket and some aluminium so I can make a blanking plate.

['Mendip Wurzel']

I would buy pass the mechanical pump, but I would leave it in place as a spare. I have doubled up with a number of things on my Lomax (ie: double fuel pumps, coils, regulators, oil pipe lines, spare electrical lines, HT leads, ignition system, throttle cable etc) 

[benchmark51]

I agree, leaving it in place makes for a potentially useful backup as well as a blanking plate.
Engines that rely on atmospheric pressure for induction are naturally aspirated, even injected ones.

[paintman]

I recently changed mine to an electric one.....best thing I've done, starts straight away with no hassle but don't forget you're
need to get a fuel regulator to adjust the pressure.

The pump should mounted so that the outlet is slightly higher than the Inlet, not horizontal.

Disregard the old pump not forgetting to blank-off the return pipe to the tank or you may get fuel siphoning from the tank
back to the engine pay when filling up.

   tony

[Gary RH7]

Many thanks for all your advice guys.

Tony,
I got a low pressure one 3 to 4psi for family car up to 2.5 Litres so should be OK for Triumph 1850 twin carb but well worth taking note of. Also mounting, good advice.

http://www.simonbbc.com/fuel_pumps/12_volt_positive_and_neg_earth_petrol_and_diesel_lift_pump_ideal_for_carbs

[Gary RH7]

Got the fuel pump plumbed and wired in. Bypassed the mechanical pump.

Switched ignition and the pump started. A bit noisy at first but expected. heard the fuel gurgling up to the carbs and the noise settled down but the pump was still pumping or at least sounding as it was pumping.
I thought these things switched off when the pressure was reached? No leaks.

Should these things stop when pressure is up?

Gary

[Lucky Ed]

Got the fuel pump plumbed and wired in. Bypassed the mechanical pump.

Switched ignition and the pump started. A bit noisy at first but expected. heard the fuel gurgling up to the carbs and the noise settled down but the pump was still pumping or at least sounding as it was pumping.
I thought these things switched off when the pressure was reached? No leaks.

Should these things stop when pressure is up?

Gary

No, they run all the time and some are noisier than others.

[Gary RH7]

Thanks Ed, excuse my ignorance on modern day stuff but what stops it from flooding the carbs and flowing into the engine or are you not supposed to just have the ignition on without the engine running ( second click on the ignition key). I suppose with the mechanical pump the engine will be running.

[Lucky Ed]

Your new electric pump will over supply the carb with fuel at all times with the ignition on, the float in the carb will regulate the flow and level of the fuel, and should stop the flow of fuel into the carb, with the engine stopped and the ignition on.
If you've got a high capacity solid state pump (Facet), you will probably need a pressure regulator, as the new higher pressure pump may overcome the float valves, flooding the carbs.

Most electric pumps for carbs supply at 7-8 psi, you will need to get the pressure down to around 2-3 psi at the carbs. A lot of the newer regulators are adjustable. Have a look on the Burton Power website, there's plenty of info on there.

[Iancider]

Yep good advice there.

There is only a needle valve between the pump and flooding the engine so a regulator is a wise precaution.

When its done let us know what it feel like with the taps fully open!

Ian

[benchmark51]

The old MGB (SU) pumps managed well enough most of the time. I dont know what pressure they ran at though. They would start and stop on demand from the carbs needle valve opening and closing. Had an MG Magnette years ago and now and then had to get out and whack the pump, as the points would stick . I think someone did a upgraded version to overcome that. Moss's would know.



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