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Fuel Pump Questions


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Hi all, hope everyone is keeping safe and well in these unusual times.

Spending (even) more time tinkering in the garage during lockdown, I have been looking at my fuel pump. The car was completely restored in the mid 90s and it looks like they installed an old style Bosch pump and left everything else alone, just as fitted by Triumph. I know the prv was replaced at the time though. The car has always run pretty well and I haven't checked the fuel pressure yet, but the pump is very noisy on start-up and runs quite noisily when on the move. The car was cutting out occasionally just briefly for a split second last time I was able to drive it, but I'm not sure that was fuel related. I have bought a new filter and thought I'd just try that, but I'm wondering:

Do I have a Bosch pump here?

Is there any benefit in mounting it vertically?

Should I put in a relay?

Is it worth shelling out on the full monty-new pump/filter/modern prv?

Searching the forums this is not a new topic-hopefully it will contribute to keeping you busy while we are "socially distanced"!

All help much appreciated.

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That looks like an early Bosch conversion to me but couldn't be certain.  Mounting it vertically probably won't make any difference.

Wiring through relay with a heavy duty fused power supply from the battery always improves pump performance by reducing voltage drop.

I would check fuel pressure at the metering unit input before thinking of changing the pump.  Should be 105 to 110 psig.

Nigel

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That's pretty similar to my set up except I have a small Carter booster  pump between the filter and the Bosch pump. The Bosch pump can't suck much but the Carter can . The booster pump keeps the Bosch pump fed when the fuel supply pressure is level is relatively low due to low tank levels or cornering.

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Yes, think it is a Bosch too, the number could be below the clamp. Vertical may wear out bearings.

Have you bought the correct replacement filter cartridge? Not all are ok although they do fit. Correct number is listed elsewhere on this forum. And sold by Revington and maybe others.

Pump suction pressure would improve by installing it lower, in the booth. Also bigger diameter inlet lines are available. 
Relay will improve performance, but not solve cavitation, which is likely your problem.
Could also be a fouled tank outlet, I had a flake of paint/rust blocking it. Resulted in cavitation and screaming (not me, the pump).

Have more fun in the shop:)

Waldi

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As per the earlier replies :

that is a classic 1990’s Bosch pump

yes upgrading to a relayed power supply is a good idea, taking the load off the ignition and inertia switches.

the part  number will be stamped on the end that’s up against the bulkhead

its a perfectly serviceable setup, although you might move to a more modern fuel filter, and perhaps the pump would be better relocated outside the boot in the wheelarch.

i’ve had that exact setup on two cars.

on the first i foolishly ‘upgraded’ to a kit from one of the big suppliers, it was no better and made a nasty noise

on the second i kept the pump and changed to a modern sytec fuel filter, as attached. post-9473-0-23400500-1535489352_thumb.png

steve

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3 hours ago, Steves_TR6 said:

As per the earlier replies :

that is a classic 1990’s Bosch pump

yes upgrading to a relayed power supply is a good idea, taking the load off the ignition and inertia switches.

the part  number will be stamped on the end that’s up against the bulkhead

its a perfectly serviceable setup, although you might move to a more modern fuel filter, and perhaps the pump would be better relocated outside the boot in the wheelarch.

i’ve had that exact setup on two cars.

on the first i foolishly ‘upgraded’ to a kit from one of the big suppliers, it was no better and made a nasty noise

on the second i kept the pump and changed to a modern sytec fuel filter, as attached. post-9473-0-23400500-1535489352_thumb.png

steve

My comments are as follows:

1) The CAV filter is prone to trapping air it and there is a bleed screw on the top lid that needs to be opened once a year to let out the air. This can cause air in the injectors if not done and rough running.           

2) The fuel pipe supply from tank to pump is on the small side should be larger in diameter, this helps to cut down the chances of cavitation. The PO has used the original fittings? I was fortunate to have access to a lathe and turned up some larger pipe fittings to suit.

3) You do not say what year your car is, as in the summer of 1972 the power wire to the pump was increased in size to cut down volt drop. This wire should be wired through a relay, with the switching wire going through the cutout s/w. Although my car is a 1973 car I rewired my power lead with 4.5mm2 wire rated at 35amps, there is no volt drop even on cranking.

4) If you have access to a multimeter with a high current range it is worth wiring the pump power lead through the meter to check what the running current is and then the check the voltage for drop.

Bruce.

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Thanks all for your help, much appreciated. I changed the fuel filter and it seems better already, less noise and smoother. I have had the car 12 years, it's a very early CR, built January1973.

Funny, I know I have changed the filter at least once before, but what I think of as recent could be years ago! I still think the restoration work is "new", since the car is 47 years old, but all the restoration stuff, including the pump. is itself 25 years old of course. If it ain't broke, don't fix it I reckon. By the way, it is a Bosch 996 pump, found its number. Thanks again chaps, keep tinkering till we can drive again-now to refit the standard road springs again-anone want a set of hardly used uprated ones-just a little too firm for my ageing posterior!

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