starter stops the diesel solenoid...

netmgr · May 9, 2008

Ive a problem on a defender 90 with a diesel engine, i bought it with a fault on the cut off wiring, which ive repaired to my understanding...

Anyhow what happens is that the starter motor seems to zap all the power from energizing the diesel cut off solenoid. ive even tried wiring the solenoid direct to the battery but as soon as the starter is turned over the cut off solenoid turns off.

There are no relays or such like involved the solenoid is direct to the battery, although it sources -12v from the pump chassis as usual.

Theres plenty of power in the battery, its actually a new battery and the fuel cut off solenoid is also brand new.

The starter is running fine, its turns over the engine with gusto

am i missing something here?

peter

slob · May 9, 2008

time to check the injun earths me thinks

netmgr · May 9, 2008

If the earth was a fault wouldnt that affect the starter motor as well?

both source their earth through the engine

slob · May 9, 2008

aye but if yer starter is using all available earthing routes it don't leave nowt fer the fuel cut off.

lectrics is funny things and behave oddly when there is an earth fault

Take5 · May 9, 2008

I concur wi that - dodgy earthing on me wiring loom caused strange things to happen wiff me reverse and fog lights when I pressed me brake pedal - mind you that was after the lake at Tong...

netmgr · May 9, 2008

ok ill go and take a look, perhaps run a seperate wire to check

slob · May 9, 2008

netmgr said:
ok ill go and take a look, perhaps run a seperate wire to check

damm fine idea just make sure its of a suitable size other wise yer starter will steal it

netmgr · May 9, 2008

still the same...

I have run an earth wire direct from the battery and bolted it to the pump bracket so its as close to the fuel solenoid as possible. I used battery cable, ie about 10mm thick. Still wont start

if i run the 2 cables to a different battery to whats starting the engine then i have no trouble at all, fires up straight away

Take5 · May 9, 2008

Reet then, deffo an earthing prob then. The tricky bit now is to find out where the blockage(s) are...

netmgr · May 9, 2008

Take5 said:
Reet then, deffo an earthing prob then. The tricky bit now is to find out where the blockage(s) are...

sorry i dont follow, if ive run a earth cable direct to the solenoid and it still wont start, how is it an earthing problem?

does a diode ring any bells to you all? ive been googling and quite often there is a diode on the solenoid, for what reason i havent yet fathomed.

Take5 · May 9, 2008

A diode will make the current flow in one direction only. For example, me offside brake light had a bad earth on it. When I hit the brake pedal, the elctricity flowed through the earth wire back into the loom and onto the earth bonding point which was also dicky. The current then flowed back along the other earth wire, through me rear fog light (which had a bad earth) back round the loom, illuminated me fog light warning lamp and then eventually found an earth. The wiring diagram nearly gave me a heart attack when I saw it for the first time - so many built in short circuits if you have a dicky earth anywhere.

A diode anywhere in the loom here would have prevented this from happening as the current cannot flow the wrong way through the diode.

netmgr · May 9, 2008

ok so you still think its an earth problem, even though ive wired the solenoid directly to the battery for both earth and +12v?

Take5 · May 9, 2008

Yes, but somewhere else on the starter side of things. You've checked engine earth strap and battery terminal, have you checked for any shorts on the positive side of things, alternator connections and cables, barrel lock etc.

Take a look at the wiring diagrams on the Rave disk and see where all the possible built in shorts are and check each one in turn.

netmgr · May 9, 2008

ok, its definately not an earth problem.
Ive run multiple earths from the battery to the engine and starter motor bolts, it makes no difference.
Also when im running the 2 battery test im using the same earth and it starts then....
im close to giving up and running 2 batteries, one for the cut off solenoid and another for the rest, its the only way ive managed to be able to start the thing.

slob · May 9, 2008

you sure yer batt int gubbed?

netmgr · May 9, 2008

well its back on charge now, but if it has the power to turn over the starter with no problems i suspect that it must be fine, that and the fact its brand new!

slob · May 9, 2008

dint mean nowt, new battery can be gash same as new anythings..

ah! ah ha! check yer ign switch you could be losing power when yer key is in the start position.

netmgr · May 9, 2008

slob said:
dint mean nowt, new battery can be gash same as new anythings..

ah! ah ha! check yer ign switch you could be losing power when yer key is in the start position.

batterys fine

the solenoid is directly connected to the battery, ingition switch is not involved

slob · May 9, 2008

so if you have it set up as it should be the solenoid loses power when yer hit the starter.

if you use two batteries and have a seperate circuit fer the solenoid, all is fine

if yer run a good earth from both solenoid and starter, then yer solenoid dunt get power.

if yer run a wire from batt to sol it loses power

is that reet?

netmgr · May 9, 2008

yes that is how it stands at the moment

Ive have double checked the fuel solenoid and its def 12v not 24v, incase they sent me the wrong one

One thing i havent done is measure the voltage at the solenoid on fail and work situations as ive misplaced my multimeter!

starter stops the diesel solenoid...

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