I am having some problems getting enough fuel to my IP when I use WVO (I have a two tank system)

So in the testing/prototyping stages I just had a small gravity feed WVO tank so I didn't need a lift pump because gravity was enough to keep the pressure up even under load. I noticed though in the last few days that under high load my IP wasn't getting enough fuel (surging, possibly the filter is getting a bit full) so I decided I better plumb in a lift pump and now its far worse so I wanted to run my plumbing past you guys to make sure I've got it right:

Now it is starving of fuel and barely makes it to 2500 rpm just sitting with me flooring it. I did a test where I pressurized my fuel tank with an air compressor and with it floored it seemed to run much better (although it was just parked, because I couldn't drive with the compressor hooked up).
I am wondering if I should put the WVO lift pump right after the tank and before the fuel filter?

Oh, it runs fine when I switch the valve to diesel so my IP and all that should be fine. Also I don't think I have an air leak because when I pressurized the tank I didn't see any of my connections leaking.

Try posting in this section;

http://www.dieselplace.com/forum/forumdisplay.php?f=298

You may get a better response.

I havent had any issues since i put a stock 93 lift pump on the WVO side.

DO you have a fuel pressure gauge before and after your filter??

What filter setup?

The filter unit I have has a built in fuel pressure gauge (its the Vormax from Plantdrive), It looks like the gauge monitors it after the filter. When I floor it and it is sitting there stumbling away at about 2000 rpm the pressure on the gauge is only about 1/3 of the way up (I'll have to check what that actually is when I look at it tonight) which makes me think that its not clogged. I don't have a gauge before the filter. I might have to look at getting one though.

I might try changing the filter just for fun tonight to see if it runs any better.

I also have a 95 tahoe with a wvo kit. My kit came from greasecar. My wvo pump is in the engine bay before the wvo filter. Dirty filter and fittings were my issue. Air leaks or any pinched lines could be a problem. With the hood closed one of my fuel lines was getting pinched, sounds retarded i know, but figured I couldn't drive around with the hood up all the time ....

Also on a separate note, my wvo lift pump is powered with a relay that ties into the stock lift pump. If your OPS is bad it may not be sending power to your wvo lift pump either.

Have you done the lift pump test in both diesel and wvo modes?

I think you have a clogged filter. The filter gauge that is after the filter but before the lift pump measures vacuum, not pressure, so the needle rising with fuel demand shows that the pump is having to pull too hard to get fuel. Try a new filter cartridge before you do anything else. The vacuum gauge really shouldn't move at all with a new filter, maybe just flick up a bit under load.

I think even a gravity feed system doesn't deliver enough fuel to the IP, if you think about it the diesel lift pump pushes maybe 7 psi to the IP, with gravity I doubt you even have 1 psi. So, it was working but probably making your IP work harder than it had to. Not sure about this, just thinking aloud. Hope this helps!

you think about it the diesel lift pump pushes maybe 7 psi to the IP, with gravity I doubt you even have 1 psi.

If you know what a gallon of your WVO weighs you could get pretty close to a real result, but === With water or diesel your vessel has to be about 2' 4" up to get 1 psi of pressure. To get 7 psi your *stuff* has to be at about 16 feet.
You could either get a pump or really tall stacks with the WVO tank near the top :) to get 7 if a gallon of your WVO weighs about 8 pounds.

Yeah, I am starting to suspect the filter was maybe just clogged, I changed it last night but I couldn't try it because I noticed one of the crappy plastic connectors came loose when I was monkeying around under the hood so I am getting some better brass ones today and I'll try it tonight.

I couldn't quite understand why it was running fine with no lift pump either but it was fine even passing on the freeway. With the new problem here though I thought I better not push my luck any longer so thats why I put the lift pump in.

I have tried the Heavy Duty Lift pumps and the 93. Both have failed after a few months. I have an additional filter underneath the truck before it goes to the stock engine bay filter. I started using the LP before my additional filter system to use it to push thought the filter instead of pull. That failed. Then I put on a LP after the addtional filter system to pull. It seems to be lasting longer. Maybe the WVO needs to go throught the filter first before the LP. Cleaner Fuel/WVO? I would still like to use some sort of higher capacity LP. Anyone find/use something that is better than the small wimpy LP's that is basically plug and play or uses the stock LP connection? The stock LP will be the weakest under full acceleration going up an incline esp tawing something. It can start to skip for lack of fuel starvation. The stock LP barely work under these conditions with regular diesel.

Mrotondi, sounds like you're plumbing is very similar to mine. My wvo goes through a heated filter, then the lift pump. It still goes through the stock under-hood filter same as the diesel. Since I didn't know the life of my old lift pump, and the fuel pressure on diesel was suspect, I put a Heath lift pump in and so far so good, though not a lot of miles on it yet.

On diesel I never get any skips under any conditions. On wvo after maybe 500 miles on the under-hood filter I'll get a skip under load, usually when the turbo spools to over 7-8 psi boost for more than a minute or so. If I put a new fuel filter in it goes away, can run wvo under full load with no skips. Not sure why this happens but its not the lift pump, its the filter. I suppose a stronger lift pump could overcome the filter back pressure better, but not a big deal to change the fuel filter when it starts happening.

Yeah sounds similar. Do you have a conversion kit that heats the WVO in a separate tank? Pulling the fuel with the LP after the extra filter seems to work better so far? What kind of heated filter system do you have? I have Ramco and heat it with the engine oil with a remote oil cooler mounted next to the filter.

Changing the filter after only 500 miles seems like a real pita. This is what I am trying to minimize in addition to getting good life out of a LP and no skipping under load.

There has to be a beefier LP than these things.

I have an electric internally heated Racor. It really doesn't heat the wvo up all that much, but it helps. I have a coolant heated hot fox fuel pickup, that's the only heat for the wvo tank.

My system when first installed wasn't getting the fuel hot enough. We added a Vegtherm electric heater just before the IP and now I have very hot fuel and things are running well for me.

I really don't have to change the filter that often. In normal driving it lasts longer, even on highway hills there isn't enough load for long enough to cause skipping. I'm really not sure what plugs up the filter, I have excellent fuel and then the Racor so really nothing should be plugging the stock filter. My guess has been that its small and not designed to pass the higher viscosity wvo, so it doesn't take much to slow the flow.

Did you speak to Bill Heath about a better LP? I wonder if he could recommend something for you once you explain the problem. He isn't too hot on the idea of wvo in a 6.5 but if he knew of a good pump he would certainly let you know.

So my engine is running much better after changing out the filter. While I was under there getting oily I changed a cracked piece of hose and some sketchy looking plastic connectors so I am still not totally sure what solved it but I'll keep a closer eye on the filter in the future. I put some clear line on the fuel return path too so I can keep an eye out for air bubbles, it actually came in really handy when I was purging the air out after changing the filter.

When I was test running/purging air out of it the transmission started shifting at full pressure because the shifts are really hard now. It was really noticeable when I was flooring it up a hill and the tires chirped on the 2-3 shift, it never used to do that, at least I know I have full fuel pressure now :D. I disconnected the battery to clear the codes and I'll see if its still doing it tomorrow. I am hoping its nothing serious.

My bike has a flat tire now too. damn

My bike has a flat tire now too. damn


Sorry if I don't have sympathy for your bike problem, but we have 5" of snow this morning! Must be nice .......

I actually moved here from Saskatchewan a little over a year ago, I sometimes forget what real weather is like. :o: