Hi again, this is what comes of being at home during the day
there is plenty of housework to do, but somehow I don't get around to it as quickly as I should....
The pump you have should be fine. I suggest you actually check the flow,
BUT BEFORE YOU UNDO ANYTHING IN THE FUEL LINE....Disconnect the battery!
If you want check the operation of the pump, run a circuit from the battery to the pump and back again with five amp electrical wire. It's worth building yourself a little circuit with proper connections and a hold down switch.. that is you have to keep pressure on the switch to maintain the circuit. Then in the event that you catch on fire, you are likely to at least stop the pump!
It's a good idea whenever you are checking fuel issues to have an appropriate fire extinguisher on hand. The one time a friend and I didn't have one, we were taught a little lesson, but that's another story... It's worth investing in a handful of proper hose clamps that can be attached and removed quickly..
Disconnect the pump output hose, fitting two metres of clear plastic tubing to a large plastic bottle, say 2 L at least....make it all secure, and keep the bottle well away from the car, and with the circuit/switch see how long it takes for the pump to fill it. A good healthy flow should be about a litre in 30 seconds or under.
Another test you can do is to disconnect the input line to the pump (should be after the filter from the tank) and check the flow just under gravity. Again, before you do this, disconnect the battery terminal so there is no chance of any spark.
To continue checking the lines, move forward and check any hose connections, any twists or kinks in the line and in particular, any loops which leave a section of the line higher than any other part before it reaches the carburettor. Ideally the fuel line should reach its highest point at the carburettor inlet – that way any bubbles are likely to get flushed out of the line when the pump turns on. Do all of these checks with extreme care. There will be fuel vapour involved, so if you can do it outside, a well ventilated shed, perhaps with a fan blowing across the car (but not closer than 3 m away).
I once rebuilt a Jaguar E type motor with Triple 2 inch SU's. It would start, it would run at low speed, it would rev with no load, but it was a complete dog under acceleration. Three weeks of investigation, which returned no improvement, ended when I finally got to the carburettor float bowls and discovered that during the couple of days I had the the carburettors on the bench, pesky wasps had filled up the inlet tubes and the CV tubes with mud, wasp eggs and paralysed spiders. Some fuel was getting through, but not enough. I guess I could have marketed the system as a way of reducing petrol consumption and promoting the environment, but it didn't work out well for the car, the spiders or the baby wasps...
Regarding shielding, if you have a weber and extractors, you're going to get a lot of heat at the back of the engine bay. Traditionally, the fuel feed comes up fairly close to the exhaust and then across the firewall. In my case, I've taken it from metal pipe at the back right hand side, even further to the right, next to the radiator and up side of the engine bay through one of the holes in the reinforcing gusset, up to the back of the firewall at the top (where the windscreen wiper cable sits) across the engine bay and down where the brake master's usually are to a fuel filter regulator, with a plumbed in electronic pressure gauge as the final component before it reaches the carburettor. if you put a pressure gauge anywhere else in the line, and may not reflect the actual pressure reaching the carb, and your regulator should be just before it, so the fuel pressure throughout the rest of the system is high enough to maintain flow and reduce vapour blocks. I know this setup contradicts what I said earlier about make carburettor the highest point, but if you shield the line (I use the corrugated metal heat/sound shielding from super cheap, it's pricey but very easy to work with) this arrangement works well.
You can also obtain heat shield for the carburettor itself, bolts on the underside, but I haven't tried that. You can also wrap the exhaust headers, and their various pros and cons to that. I know that in some racing setups, the fuel line goes through a bucket of ice or chilled water, but this doesn't really work for a road car (although you could incorporate a champagne bucket.
I know these issues can be irritating, particularly if you have to get someone somewhere at a certain time... but if you have a bit of time, it can be quite interesting to chase down these little gremlins. Often the solution is very simple. An old mechanic I used to work with said that whenever there was a problem with an engine, it was either "fuel or spark" and that's still true in most cases, although I would add "operator error" as being just as prevalent a cause in my case, coupled with a complete inability to leave anything that's running well, well enough alone....
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