Michael, you probably have a high resistance wiring line. Your test shows
12-V, but that's under a very lightly loaded condition, as the test lamp
draws very little current. When the pump draws current, the voltage at the
pump is droppng, somewhere along the 12-V feed.
Check the connections at either end of the fuel pump circuit, and especially
the ground connections.
Good luck!
== Alex in Maine, The Blue Mainie 1960 BT7
-----Original Message-----
From: owner-healeys@autox.team.net
[mailto:owner-healeys@autox.team.net]On Behalf Of Awgertoo@aol.com
Sent: Tuesday, October 04, 2005 3:58 PM
To: healeys@autox.team.net
Cc: caahc@yahoogroups.com
Subject: Fuel Pump Circuit
My wife's 3000 died over the weekend. On initial investigation it cranked
fine and had a spark but empty fuel bowls.
When I turned on the ignition I did not hear any ticking from the SU (her
car
came with one of the double-headed models) so I checked the circuit to
it--test meter showed 12 volts. I disconnected the fuel supply line--The
pump would
give one gasp and emit a short burst of fuel when the ignition switch was
turned on and no more. Same thing when I turned the switch off-one click
and that
was it. I removed the pump and checked it on the bench--same deal.
I went to the NAPA store and bought a FACET pump. Checked it on the bench
and it was fine. I wired and plumbed it in and with the ignition switch
turned
on it clicked away and apparently pushed fuel to the engine. However,
whenever I started the engine the fuel pump would die--I could feel it stop
clicking
at the same time that the green "ignition warning" light would go off--and
within a minute or so the engine would die. I could also see that the fuel
was
not being pumped into the transparent inline fuel filter.
When I turn the ignition switch off and then back on the fuel pump energizes
and keeps on ticking (less intensely once the system is pressurized) but as
soon as I push the start button and the engine fires over the fuel pump
switches
off!
Here are some other observations:
1. If I wire the pump directly to the battery there is no problem. The
pump
will of course run with the engine off or on. I can see fuel being pumped
into the transparent fuel filter.
2. When I run a test light to the fuel pump power lead it lights when I
turn
on the ignition switch, blinks or dims a bit during starting (never really
goes out), and stays lighted when the engine is running (this with the fuel
pump
wired directly to the battery as in #1 above.)
3. When I attach a test meter to the fuel pump power lead the voltage is
around 12 with the ignition switch on and the engine off. On startup the
voltage
goes up to 13+ (it's an analog meter and I'm testing on a 50 volt scale so I
cannot get precise readings.)
Best I can tell something is kicking the fuel pump off when the engine
starts
up but I am lost. I have an alternator if that is important. The pump is
wired for negative ground.
Any suggestions will be appreciated.
Best--Michael Oritt
|