Fv432 blocked fuel filter

[ChasSomT.]

Maybe I should have posted in 'I may be stupid, but. . ' instead

 

We've got a blocked fuel filter in the collecter tank of our 439, WE THINK.

The book keeps on about a drain valve, accessable from underneath the rear of the vehicle.

We've taken out both brass plugs and found nothing. A few drips of fuel, nowt else.

Drain valve, what drain valve? Any suggestions, please?

 

And while I'm on, has anyone any idea how to switch on the fuel pump to the gennies on 'the roof'? (439Message Centre)

A long shot, I know, but someone may know! We may have some harness missing, but can't find a switch specifically for the pump. Maybe the pump only runs when the gennies are started, but then, it would take a while to prime the fuel lines I would have thought.

 

Thanks, Chas.

[sirhc]

Chas,

 

Have you lifted up the cover plate over the fuel pump? I think that's what it means by the drain valve?

 

Chris

[andym]

There's two separate things here - the collector tank and the drain valve. The collector tank is reached through the removable section of the floor plate, the drain valve is reached through the plug underneath the rear of the vehicle.

 

To drain water from the collector tank, release the lock nut on the valve at the end of the tank opposite from the fuel pump. Unscrew the valve pin. Drain until clear fuel flows and then close the valve and tighten the locknut.

 

To drain the fuel tanks using the drain valve, unscrew the regulating plug (the larger of the two) and the short plug (the smaller of the two). Then screw the regulating plug into the hole where the short plug came from, which will open the valve and allow fuel to drain. The further you screw it in, the faster fuel will flow. Put both plugs back where they came from on completion.

 

For the roof generators, the fuel pump is fed via a circuit breaker on the "Unit, Control and Distribution". To the right of the elapsed time indicator there is a line of four circuit breakers and it's the last one. From the wiring diagram it looks as though the Silent Watch switch must be "Off" to power the fuel pump.

 

I hope that makes sense!

 

Andy

Edited August 28, 2010 by andym

[ChasSomT.]

Thank you for your replies, very helpful. Clever, that, about swapping the plugs around.

Will try that asap!

I actually managed to trace the gennie fuel pump cable back to the board, and found a 'trip' out, but still no 'joy'! Will try the switch you mentioned.

 

Thanks again.

Chas.

[andym]

Glad to be of service! :-)

 

Andy

[Diesel demon]

If the gennys are Onans there is no fuel pump as such, disconect the external (remote) start leads (the leads that run into the back of the 43) and start it from the switch located on itself.

This will prove the gennys work.

 

There is a circuit breaker for each genny on the remote start board, check them, failing that the only thing it can be are the leads themselves

 

Heres hoping

[ChasSomT.]

Andym: You have wiring diagrams for the gennies on 439s? Wow! Any chance of a copy?

Dieseldemon: There's Definately a fuel pump, and Another filter, on the R/H side, on the tank. Not certain if they are Onans, look Very similar to Petter AC1s to me. Plessey Aerospace (or something) data plates on them!

Thanks lads!

Edited September 3, 2010 by ChasSomT.
Plessey Aerospace, Not 'International' Doh!

[andym]

I'll PM you about the drawings!

 

I think you'll find there were two types of generator fitted to the FV439s depending on their age and role. The first ones were petrol driven AC generators, which I think are the Onans. They had independent tanks on the roof, hence no electrical fuel pumps. The FV439 SAS/MC was fitted with diesel driven 28V DC generators, which take their fuel from a tee into the right-hand fuel tank with an electrical fuel pump by the side of it.

 

Andy

[ChasSomT.]

An update on the fuel 'starvation' situation - I finally got round to extracting the pump filter, took it to work, and gave it a 'great deal of attention'. Refitted it tonight and she goes like 'a dream'. Thank you to all who gave advice - 'Always I am learning'

 

At an 'H 4 H' event over the Bank Holiday week end, I had time to sort through one of the bins on top (FV439 Message Centre) and found nearly all the cables and hoses to connect up the gennies. I had time tonight to fit most that were needed, and, 'Wot's think'? I actually managed to fire up one of the gennies ! Result ! One 'trivial detail', the fuel return hoses weren't there, and the vehicle-end connection has been blanked off, so we've got a bit of fuel running out of one of the gennie housings , and down the side of the vehicle, but 'Chuffed'? I should say so !

I don't know what to do with the 100 Amps of 28V I am producing, Or capable of producing, but as the BV doesn't seem to work, maybe I shall try and hook that up!

Chas.

[andym]

Hurrah! :-)

 

Andy