Classic cars forum & vehicle restoration.

ukdave2002 · Joined: 23 Nov 2007 Posts: 4276 Location: South Cheshire

Is the pump getting power or is there zero output from the timer?

alastairq · Joined: 14 Oct 2016 Posts: 2135 Location: East Yorkshire

Ray White · Joined: 02 Dec 2014 Posts: 7234 Location: Derby

I am utterly confused.

I have mounted the pump assuming it was insulated. There are two wires coming from it; a red and a black. As suggested, I have swapped these over on the relay. Now the red wire goes to 5 and the black goes to 2. The red is also connected to the new red ignition switched wire via a double connector after the 10amp fuse.

The switch body is earthed (black) via the chassis as per instructions and another black wire from the switch connector goes to 3 on the relay. No.1 goes to earth. (There is no No.4)

Switched on and the Ignition warning and oil pressure lights have gone out.

I just can't do this anymore.

alastairq · Joined: 14 Oct 2016 Posts: 2135 Location: East Yorkshire

Like I said, there may be an assumption that applications will be negative earth.

Try lifting the actual body[of the pump] clear of its chassis connecting bolts....to remove the chance the pump is not insulated from its base. Therefore not in contact with the car's structure, which will be positive [earth]!
Then just make some temporary connections to the pump leads, as ukdave has suggested?
Just to see if the pump runs?

If it does, without creating other issues, then the solution would be, to mount the pump fully insulated from the car's structure, wiring as above???
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Dellow Mk2, 1951 built, reg 1952.
Fiat 126 BIS
Cannon special [1996 registered. Built in 1950's]
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Ford Pop chassis, Ashley 1172 bodyshell, in pieces.

Ray White · Joined: 02 Dec 2014 Posts: 7234 Location: Derby

ukdave2002 · Joined: 23 Nov 2007 Posts: 4276 Location: South Cheshire

To see if the pump body is "earthed" simply do a continuity test between the case and the black cable, I had considered this but looking at the anti vibration pump mounts in the picture, I'd assumed that even if the case was grounded, the mounts would provide insulation.

If the pump case is "earthed" it would explain why nothing is working! but I would have expected the 10A to have blown.

Ray White · Joined: 02 Dec 2014 Posts: 7234 Location: Derby

ukdave2002 · Joined: 23 Nov 2007 Posts: 4276 Location: South Cheshire

Ray White · Joined: 02 Dec 2014 Posts: 7234 Location: Derby

ukdave2002 · Joined: 23 Nov 2007 Posts: 4276 Location: South Cheshire

Ray White · Joined: 02 Dec 2014 Posts: 7234 Location: Derby

As it happens, I have needed to resort to an electric pump as there is insufficient vacuum at the manifold due to pressurisation by the supercharger... so I moved the take off to the throttle plate (between the carb and the blower) where there should be a vacuum on over run but it caused the engine stall when the brake pedal was depressed.!

Having given up on an induction based system I removed the hose and installed a 'remote' electric vacuum pump despite having misgivings about the potential noise element.

All depression points have now been blanked off leaving the engine free of any external influences.

I am hoping that this independent electric vacuum pump will be the answer. It will concentrate the supply through a shorter hose length and neatly restricts the servo system to a small area behind the seat. If it fails then at least I can still use the car without servo assistance to the brakes.