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gas tank conversion to diesel review

2645 Views 20 Replies 6 Participants Last post by  Broncoduecer
converting my 94 d-90 #199, to a tdi 300
engine and transmittion rebuild and installed
working on electrical, thanks to advise from posts
have dropped the tank, disconnected the fuel pump,
I have unhooked the fuel supply and return hoses from the pump
I plan to extend the supply line to about 3/4 on an inch from the bottom of the tank wjth addrd screen to the end of the line
the return I was going to just let it dangle loose.
as for the two little black hoses I am thinking of blanking them off
I also took out the gas fuel filter and patched the line

is this generally acceptable?

kim
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For the diesel you need a supply and return line as well as a vent for the tank. Some of the diesels have a sediment filter as well as a fuel filter. The fuel filter is in the engine bay close to the injection pump. The sediment filter is on the RR frame in front of the rear wheel. (not all applications had this). The Td5 tank had the fuel line coming out of the top. It has a hard line that goes down into the swirl pot and a rubber line connecting the outflow to the hard line on the frame crossmember.
This should help...

converting my 94 d-90 #199, to a tdi 300...is this generally acceptable?

kim
Kim:
You will want to remove the pump and have an open fuel pickup, then a sedimenter, then a 12V electric low pressure pump, then the diesel fuel filter and the IP. The electric pump will save you loads of trouble eliminating fuel starvation on conditions like fuel filter changes and bleed down if you park at angles while off roading while you wait for the line to move through. This is not common, but have seen it happen. Have also seen where trash will block a fuel pickup screen, but when the pipe is open trash will get sucked through the pipe and become trapped in the sedimenter. This happened to Jonathan at the cove and has happened to others as well. Then there is the case where you run out of fuel and have to bleed out all the air by cranking and cranking or operating the lift pump by hand... without a 12V pump.

The old V8 gasoline fuel filter is NOT compatible with diesel and needs to be removed.

I always extend a metal pipe down to the bottom for the fuel pickup and the return can be a pipe or just open so the fuel drops in from the top, but it is not wise to leave a dangling hose that could interfere with the sending unit level and provide a false reading.

Hope this helps.
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do you have a source for the pump?
Pump Info...

do you have a source for the pump?
Airtex E8012S available from any decent auto supply.
Thanks, will check this out.
Does this mean that I do not need the mechanical pump? or is this in conjunction with the mechanical pump?
in conjunction with....

Thanks, will check this out.
Does this mean that I do not need the mechanical pump? or is this in conjunction with the mechanical pump?
Search sedimenter and you'll see a picture of a 110 with sedimenter and pump at the end of the thread:
Thread = Defender Source > Defender & Series Technical Discussions > Defender Technical Discussions > Sedimentors

Hope this helps.
ok, got the info about the sedimenter, but does the electric pump cancel out the mechanical pump on the engine?
the model number you gave me is for a gas engine the one for diesel is 110-E8153
it is an external pump
is that what you are recommending?
the model number you gave me is for a gas engine the one for diesel is 110-E8153
it is an external pump
is that what you are recommending?
Airtex E8012S is actually a universal pump that works with gas or diesel.
If you looked up the thread I referenced for you, it shows a picture of this pump which is not mounted in the fuel tank (external).
Since you want the pump AFTER the sedimenter, it has to be mounted outside the tank.
Do NOT use E8153... at one point about 5 years ago, decided to try this pump on 2 of our vehicles.
Within a month both stopped working. So we replaced with the E8012S and both are still working fine (after about 5 years).

ok, got the info about the sedimenter, but does the electric pump cancel out the mechanical pump on the engine?
Am not aware of there ever being a condition where by an electric pump will "cancel" out a mechanical pump but you do bring up and interesting point.

I suppose if the mechanical pump failed and the fuel could route it's way to the IP through the failed mechanical lift pump, then the engine would continue to run or under an even more rare condition pump fuel into the engine crankcase.

The electric pump will make sure the mechanical pump has a steady flow of fuel under any condition, but it won't cause the mechanical lift pump to fail that I'm aware of... at least none of this has ever happened to me in 25 years starting with a 109 2.25 diesel pickup.

But have been on trail rides where people will loose prime and fuel starve an engine and have to get towed to flat ground to get the engine to start.

When I first installed the Mercedes OM617 5cyl Turbo Diesel in the 110 pickup last fall, was rushed to get to the Cove for the Conclave 2012 and then on to Uwharrie, so I didn't install the sedimenter and 12V pump and learned my lesson. I ran out of fuel on the way home and after walking about 60 yards up the interstate ramp to fill a jerry can and pumping the hand primer about 300 times with no joy. Three hours later a guy towed me up the ramp in 5th gear and got it started. What a miserable experience. The following weekend installed the sedimenter and 12V pump and ran out of fuel a few weeks later. While fueling switched the key on which filled the system via the 12V pump (no manual priming needed). Then started the engine and immediately drove away. Now just need to replace the fuel gauge and sender which sometimes fails to drop below the 1/4 mark! For now have learned to fill up when the needle gets close to 1/4 tank of fuel. The warning light works, but only gives you a few miles of driving for some reason.

If you're leery of the E8012S electric pump you can leave it out, but they have always served me well with no issues.
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I installer my new LR factory 300tdi re-power kit in July 2001. I now have 130K+ miles on the engine at this time. I have a different opinions about some items previously mentioned here.

1). The V8 gas filter, I left mine in place, once the tdi started to "not run as fast", turned out the V8 gas was getting a little plugged, replaced it and full power was restored. V8 filter still in place & I do employ the standard diesel filter under the bonnet too. I've only changed it once in all these miles.
2). The in tank pump was removed and a short section of tubing took it's place, still working fine after 11+ years. The fuel pump on the side of the engine works just fine to "lift" fuel to the filter & bleed off air when you change out the normal diesel fuel filter. An elec pump may be handy but it's not necessary.
3.) The return fuel line can be used as from the gas engine. Make sure you hook up the fuel lines (up-take & return) correctly at the tank as you re-install the tank, otherwise you will run out of fuel at about 3/8 of a tank and it will drive you crazy that the engine won't run while having fuel in the tank.
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Lucky man... having a gasoline filter inline is not the preferred setup.

I installer my new LR factory 300tdi re-power kit in July 2001. I now have 130K+ miles on the engine at this time. I have a different opinions about some items previously mentioned here... 1). The V8 gas filter, I left mine in place...
With the little gasoline filter as your "first line of defense" you are lucky to have gone so long and so far with this being the first unit the fuel passes through.

We installed an Isuzu 4JB1-T in a 1993 Classic RR with completely different results, although we never tried changing the little gas filter after it kept the engine from going over 25MPH. The gas filter is working for you, but is potentially putting extra stress on the lift pump because it will restrict the suction side of the fuel system and is NOT the sort of piece you easily change out by the side of the road, but a sedimenter in it's place can easily be drained with a thumb screw. Also in its "natural" state, the gas filter has a high pressure pump pushing fuel through it.

You have also set yourself up to not have a water trap in your fuel system and when you get water in your fuel, you're pushing it through your pump and etching your injectors.

You were smart to have replaced it, but would have been smarter to just remove it.
There is not a diesel setup manufactured anywhere that I know of that left any factory with a small gasoline filter back by the fuel tank (on the suction side) that can clog and stop the engine.

Have you tried any bio-diesel?
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Wasn't there also some big discussions on venting or not venting the tank, and then which fuel cap to use as well? I seem to recall something about that.
Hi,
I have assumed that it would have to be vented, since this is not a pressurized system.
However I am not the best person to ask.

kim
Only a doofus would argue against venting the tank. That is, of course, they enjoy having fuel blast out the filler neck when the tank is filled.
The original V8 has a tank vent system that has 2 valved vents on the top of the tank. Those vents combine into 1 line that goes to the engine compartment. The valves on top of the tank are spring loaded to allow air into the tank but don't allow fuel into the vent line. On the '97 with the OBDII system, you will get a (CEL) check engine light (leave the gas cap off) IF the fuel system is not pressurized (cap screwed on tightly).
With the little gasoline filter as your "first line of defense" you are lucky to have gone so long and so far with this being the first unit the fuel passes through.
The gas fuel filter is far from "little" !



You have also set yourself up to not have a water trap in your fuel system and when you get water in your fuel, you're pushing it through your pump and etching your injectors.
As you must have missed in my 1st post, "I do employ the standard diesel filter under the bonnet". This filter DOES catch water !!

You were smart to have replaced it, but would have been smarter to just remove it.
Like previously stated, I have replaced it once when it was starting to get plugged. When it started to get plugged, the engine was starved for fuel, above which the engine would not run at a higher rpm. Hard to argue with 11+ years and 130 thousand miles of experience !!

Have you tried any bio-diesel?
Only inadvertently, I love good old fashioned dino fuel .... the Original GREEN fuel as it came from rotting plant material from long ago.
The original V8 has a tank vent system that has 2 valved vents on the top of the tank. Those vents combine into 1 line that goes to the engine compartment. The valves on top of the tank are spring loaded to allow air into the tank but don't allow fuel into the vent line. On the '97 with the OBDII system, you will get a (CEL) check engine light (leave the gas cap off) IF the fuel system is not pressurized (cap screwed on tightly).
Yeah but if it is converted to diesel why would anyone still have a bulb in the CEL dummy lamp? For that matter why even have any of the OBD2 schmidt in the vehicle. Just rip it all out. #worthless. Did d90s have OBD2 in 1994? My 94 RRC still has the Lucas-Rovacom thingy.
Yeah but if it is converted to diesel why would anyone still have a bulb in the CEL dummy lamp? For that matter why even have any of the OBD2 schmidt in the vehicle. Just rip it all out. #worthless. Did d90s have OBD2 in 1994? My 94 RRC still has the Lucas-Rovacom thingy.
Yes, I did pull all that crap out & sold it with the gas motor. The point I was making was that MY vehicle is a '97 and this thread started dealing with a '94 vehicle which has the OBD-I system. Don't know if a loose gas cap will give off a CEL lamp for pre-OBD-II systems.
The gas fuel filter is far from "little" !
The dimensions are small and the amount of particulate it can trap a fraction of what a "real diesel filter" will hold and still allow fuel to pass. So it is full size by gasoline standards and small small small by diesel standards! Your small gas filter even started to clog up at first. Also your replacement must have had universal media unlike some of the paper filled ones that are NOT diesel compatible. I have always cut open clogged filters to see what's inside and what did the clogging up and most of the original filters have paper elements.

As you must have missed in my 1st post, "I do employ the standard diesel filter under the bonnet". This filter DOES catch water !!
Didn't miss anything you typed, was talking sedimenter (which you may have missed yourself not fuel filter) which will trap as close to 100% of the water as you're going to get with an inline filtration system. The diesel filter element is designed to trap particulate and not rated to trap any quantity of water unlike a sedimenter that does trap water. The fuel filter media will swell with water. When water is trapped because of gravity not anything else special, depending on the element type, will leach more or less of the trapped water into the fuel and give the conditions I described earlier + white smoke and will even cause the engine to shut down with any throttle pressure if it gets close to full.

Like previously stated, I have replaced it once when it was starting to get plugged. When it started to get plugged, the engine was starved for fuel, above which the engine would not run at a higher rpm. Hard to argue with 11+ years and 130 thousand miles of experience !!
You are lucky, so keep bragging on just how lucky you are just to ignore sound advice... If that SMALL gasoline filter were such a good idea, all the 200 & 300TDS would have left the factory with one. Ask Uncle Douglas about getting a bad batch of fuel. I got one batch that required me to empty my sedimenter a half dozen times on a trip from VA to NY... this fill up would have stopped you because you have the small V8 gas filter and the standard diesel filter you described earlier without a sedimenter. There must have been a gallon of water in that 15 gallon fill up...
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