From: Bill & Bonnie Prestin (bprestin@chartermi.net)
Date: Sun Feb 15 2004 - 12:07:15 PST
I hope Caleb's SVO fuel system is successful. It is good to think the
system through before making the conversion. The plumbing is very important
for it to all work right.
I'll tell about what I have been experiencing with my dual diesel tanks.
I have a dual tank setup on my deuce. I have been having some very!
annoying difficulties with the plumbing of the system. My system is
controlled by a switch on the dash that operates a relay which controls
switching of the in tank fuel pumps and in tank level sensors for the fuel
gage. When I switch to the left tank it runs the left fuel pump and uses the
left level sensor, etc. I have had some difficulty locating any 24 volt fuel
solenoids that don't need a significant differential pressure to operate. So
the way I set up the system is, the fuel coming from the fuel pumps goes
through check valves then connect together into a single line and goes to
the engine. That way whichever tank is selected is the one that supplies the
engine, but it cannot back-feed into the other tank because of the check
valves. The returns go through a manual selector valve to select the tank to
return the overflow fuel (from the engine) to.
The problem I have is, the check valves operate on such low pressure
that they keep getting stuck and send fuel from one tank into the other.
This tank then overflows. I had to reroute the tank ventilation system
because the first time it happened fuel filled the other tank, then pushed
up into the trucks entire vent system putting diesel into the engine
crankcase, air cleaner, all gear boxes, break system, etc. I then lost a rod
bearing and when trying to back it down a slope into the shop, excess fuel
dumped out of the air cleaner into the engine and it ran away (the engine
ran away) and I thought it would explode. I pulled the engine stop lever and
ran for it. Luckily, the truck coasted onto level ground, and the engine
stalled when it ran out of fuel.
I have since drained all fluids and replaced them. I had to pull the
engine and replace it also. I routed the vent system with the fuel tanks
separate from all the others. I cleaned out the stuck check valve, and
thought I had solved the problem. (not!) It happened again and I lost some
diesel out the separate vent line and could only use one tank for the
remainder of the trip.
What I would like to do is eliminate the check valves and manual return
valve altogether. I would like to install two 24 volt fuel selector valves
to route the supply and return fuel lines automatically when I switch the
selector switch on the dash. Does anyone know of any fuel selector
valve/solenoids that operate on 24 volts DC and that don't need a high
differential (pilot)pressure (I think the in tank pumps provide less than 15
lbs, probably 5 to 7 lbs pressure) Anyone know? I would prefer very high
quality ones with metal fittings if I can find them. Everything I have seen
is the cheap plastic 12 volt ones for modern trucks.
Any ideas anyone!!
Caleb?
Bjorn??
(you seem to be able to find or make just about anything!)
Thanks,
Bill
Michigan
----- Original Message -----
From: "Caleb Pal, Network Operations" <sysop@spitfire.homelinux.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Thursday, January 29, 2004 1:08 AM
Subject: [MV] M35A2 SVO Conversion (More questions and info!)
> Hello all,
>
> Thanks all for the replies to my last post about the SVO conversion I
might
> be going into soon. I looked at the possible donor truck today and had a
> fewthe injection pump there is a tee questions. On the main 2 fuel filters
> by on the inlet of the first big filter. The tee seems to tee into the
fuel
> filter inlet. Of the 2 inlets of the tee, one goes to the return line to
the
> tank, and the other to the return line on the IP. So it seems that any
bleed
> off from the injector pump is sent to the main filter set, and if its too
> much, it bleeds off into the return to the tank. Also it seems if the fuel
> pump pressure is too much, it will return it through the tee, into the
> return line, into the tank. For my conversion, I would need to take that
tee
> out, because when I use SVO, it will return SVO to the diesel filter set,
> which isn't good. Let me back up for a second, this is really difficult to
> explain in words. I will have 2 tanks, one is just another duece tank with
> SVO and a coil inside to warm it up. It will have an in-tank pump to send
it
> to the solinoid valve. At the solinoid valve, there will be 2 inputs,
diesel
> and SVO. From there it will go strait into the IP. The diesel will be
> filtered by the original filter set. The SVO will have a filter right
before
> the solinoid valve. The return will have a solinoid valve that will be
wired
> to the main solinoid. So the return fuel will go to the right tank. If its
> SVO, it will go to the SVO tank return. If its on diesel, it will go to
the
> diesel tank. This is where I have questions. The return that plumbs into
the
> first big filter, with the tee, if I keep it there, like I said before,
when
> on SVO will pump svo into the diesel line. Can I just take that tee out,
and
> just put a coupling? Plug the hole in the filter? Or will this cause too
> much back pressure and wear on the in-tank pumps? Option #2 is to take a
3rd
> solinoid (This is getting more confusing, very sorry). The 3rd solinoid
will
> have one inlet and 2 outlets. The inlet will be the tee that used to go to
> the first big diesel filter. The outputs, one will go to the place where
to
> tee used to be, so when the solinoid is off, it will be like a normally
> plumbed duece system. As soon as the #3 solinoid is switched, it will send
> that return tee line to a tee right before the SVO filter. This is keeping
> the diesel and SVO seperate. If I could just plug the tee hole and put a
> coupling in, it would be easy, but if it will blow pumps, il'l plumb #3
> solinoid. Another thing, the fuel compensator. Right before the injector
> pump there is a metal thing that is attached to the IP. It has some
fittings
> on it, and there are 2 tees, both have tubing that loop back to
themselves.
> One on the front, one near the back. This seems to be like its been taken
> out of the system. Not a big deal, I think I can do without it for this
> project. I have a diagram of all of this, just no way to scan it in. I
hope
> this makes some sense. If not, feel free to e-mail me and ask questions. I
> will be out of town till friday night, so I won't be able to get back to
> anyone till then.
>
> Thanks so much!
>
> Caleb Pal
>
>
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