6.5TD - hunting airleaks and considering FTB mod

[Svein]

I´m at what I thought was the end to my big project of converting my 6.5 suburban into running on wvo.

I have re-done all the fuel lines (except the diesel return line, I ran out of hose, haha

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), and made an almost identical setup for the diesel and the wvo like the following:

Diesel side:
tank->inline plastic prefilter->T out to diesel heater->acdelco ep1000lift pump->coolant heated 10micron filter->selection valve

WVO side:
tank->inline plastic prefilter->acdelco ep1000 lift pump->coolant heated 10micron filter->plate heat exchanger->selection valve

Common, after the selection valve, the lines run like this:
selection valve->electrical heater (for wvo)->T for temp gauge->T for fuel pressure gauge->original fuel filter manager.

From there onwards it´s stock until I´ve connected onto where the rubber hose from the ip/injector return to the diesel hard line was, where I´ve connected a rubber hose to/from the return fuel selection valve. I have a clear plastic pre filter here as well to monitor the return fuel.

I also have fuel pressure gauges between the lift pumps and the filter in both lines.

The truck runs well, and I can read pressure between 4-7psi on normal driving, lowest I´ve seen is 1,5 at WOT, and the highest is 8ish with lift pump running and engine off. However, it dies after a while (like 5mins of calm driving) when I am running it on WVO, and I can see that it sucks air somewhere even on the diesel side.

I can see some very small air bubbles being sucked into the pre filter on the dieselside - almost invisible. On the filter on the return side, however, a rather large air bubble comes into the plastic inline filter every 5-10s.

I´ve been trough all the connections I´ve made and re-tightened them, without any luck, so I fear that it might be sucking air either from the fuel filter manager, or from the line from the FFM to the IP.

I´ve bought clear tubing for testing purposes, and I am taking the sub to a shop on Monday to try to hunt down the air leak(s) again in temperatures above freezing, but all this doing my regular job and not being able to play with my car has led me to thinking (a bit to much), so I have some questions I´d like to ask:

1. The plastic inline filters do not fill up with fuel. On the feed side, it´s a small air bubble, and on the return line a much bigger one. When I´ve been driving the truck, and I stop and idle for a while, it fills a bit, but still with a large air bubble. Google has told me that air bubbles in inline filters are completely normal and not dangerous. Any opinions here?

2. The diesel return line is the original line, so it can definitively have some leaks I haven´t seen. I´ve been reading up about it, and some people say it will affect the fuel system, some claim it doesn't´t matter. Opinions?

3. If my next quest for the air leak(s) doesn't give results, the only thing I haven´t exchanged or improved is the FFM and the line to the IP. I´d have to order the seals for the FFM from the US, so I´m considering ordering a kit for the FTB mod to do it while I have the FFM out anyway. It would make it even easier to T in a fuel pressure gauge AFTER the FFM which I am quite keen on having. However - my budget for this project is well spent, and I can´t really see myself buying new lift pumps again as well. Would the FTB mod work with the EP1000 lift pump, or is that asking for even more trouble?

Thanks for all answers and guidance. This newbie is learning every day on this forum!

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Cheers,
Svein

 

[tanman_2006]

Not to run you off from this forum but you will get a lot more help with your 6.5 on thetruckstop.us. There are a lot of very knowledgeable 6.5 guys there and some have also dabbled in WVO (not many people with good experiences anywhere though)

Hope to see you posting over there

 

[tanman_2006]

How are you determining that you have air leaks? The most common way is a clear hose on the return pump out of the IP.

The clear plastic filters do hold a little air but as they get clogged they will push the air out and fill with diesel until the filter plugs. This is not enough air to really hurt anything.

Leroy Diesel and Quadstar Tuning are 2 very good parts dealers in the US and they do offer over seas shipping options.

 

[Svein]

Not to run you off from this forum but you will get a lot more help with your 6.5 on thetruckstop.us. There are a lot of very knowledgeable 6.5 guys there and some have also dabbled in WVO (not many people with good experiences anywhere though)

Hope to see you posting over there

I know - I fell in love with this forum - it´s such a nice vibe here, and a lot of the information works both for gassers and diesel! But good Idea posting over there as well! Thanks!

How are you determining that you have air leaks? The most common way is a clear hose on the return pump out of the IP.

I have one of the clear filters after the combined return from both the ip and the injectors, and I can see big air bubbles coming in with the fuel every 5-10s, so there is definitively air in the system!

The clear plastic filters do hold a little air but as they get clogged they will push the air out and fill with diesel until the filter plugs. This is not enough air to really hurt anything.

That´s great to know. Then I can stop worrying about that!

Leroy Diesel and Quadstar Tuning are 2 very good parts dealers in the US and they do offer over seas shipping options.

Thanks! luckily, shipping stuff over seas is not the big problem - the problem is the wait and the shipping costs. Especially the wait! So I'm considering ordering a "feed the beast" mod while ordering other parts - but unsure if I´ll just create more trouble for myself by doing the FTB mod.

 

[tanman_2006]

Thanks! luckily, shipping stuff over seas is not the big problem - the problem is the wait and the shipping costs. Especially the wait! So I'm considering ordering a "feed the beast" mod while ordering other parts - but unsure if I´ll just create more trouble for myself by doing the FTB mod.

The ftb isn't going to hurt anything. Quadstar offers a nice kit for that.

My opinion on the set up is you need to push fuel through the heater, not pull it.

If you change that and still have bubbles then you might have a couple pin holes in your pick up tube.

 

[Svein]

The ftb isn't going to hurt anything. Quadstar offers a nice kit for that.

My opinion on the set up is you need to push fuel through the heater, not pull it.

If you change that and still have bubbles then you might have a couple pin holes in your pick up tube.

Yeah, maybe I should just go ahead and order a FTB kit. Spent way too much money by now anyway, so might as well go the extra mile!

I think you misunderstood the heater bit? I have a tee fitting between the screen filter and the lift pump that runs a 4mmish fuel line to an ardic diesel heater (similar to webasto or ebersprecher). This one has it´s own ancient lift pump for its operation. Basically my LP is pushing the fuel all the way after the pre-screen filter to the IP.

The tank and the pickup is also new, or at least half a year old, I bought it from a guy who had no pre lp-filter and couldn´t get the truck to run after a while. Wonder why..

Thanks for good advices anyway! Tomorrows quest will show if I manage to improve the system!

 

[tanman_2006]

Yeah, maybe I should just go ahead and order a FTB kit. Spent way too much money by now anyway, so might as well go the extra mile!

I think you misunderstood the heater bit? I have a tee fitting between the screen filter and the lift pump that runs a 4mmish fuel line to an ardic diesel heater (similar to webasto or ebersprecher). This one has it´s own ancient lift pump for its operation. Basically my LP is pushing the fuel all the way after the pre-screen filter to the IP.

The tank and the pickup is also new, or at least half a year old, I bought it from a guy who had no pre lp-filter and couldn´t get the truck to run after a while. Wonder why..

Thanks for good advices anyway! Tomorrows quest will show if I manage to improve the system!

AHHHH! One of those real heaters.

That said... I'm affraid that might be where your air leak is coming from on the diesel side. The LP will pull fuel from that system too if there is a slight seep in the seals (path of least resistance). I'd look into some sort of fuel shut off valve that you could install to remove it from the equation.

 

[Svein]

AHHHH! One of those real heaters.

That said... I'm affraid that might be where your air leak is coming from on the diesel side. The LP will pull fuel from that system too if there is a slight seep in the seals (path of least resistance). I'd look into some sort of fuel shut off valve that you could install to remove it from the equation.

Yes, one of them real ones! I got lucky - truck I bought had and old one, and I managed to fix it and put a remote on it. works like a charm!

I had great success on the airleak today! Turned out when I added a couple off clear hoses, my fuel system was tight - and the leak was in the T I used to connect the clear pipe on the return line. How stupid!

At least I know my system is good - but I am running with too weak lift pumps. I cruise at 5-6psi, and on the wvo side it feels like the system is not getting enough fuel. I think I need to upgrade both lift pumps to have a happy truck. And I might just add a FTB-kit while I´m at it.

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[tanman_2006]

The carter lift pump is supposed to a good pump. I'm not sure how it does on bio/vegie though

 

[Svein]

After reading a bit and talking a bit to plant drive who supplied the wvo stuff, I am leaning more and more towards Walbro FRB-5 that is rated for biodiesel.

Had a bit of a day today. Was supposed only to be thinking about which lift pump to install, but then my girlfriend called me cause the car was stopping. Turned out to be a blocked LP pre filter on the diesel side. Good thing I have that filter there, cause the new fuel tank I bought "only used 4 months" is full off all kinds of crap, and even though I did a good cleaning of it before putting it up it gives away fresh debris all the time. *sigh*

Anyway, as tonights plans was cancelled, I did another wvo test-run after having gotten some tips to try from plant drive who sold me the wvo parts. He did not think the lift pump was the problem since the truck was ideling well, but was mentioning the following possible problems:

1. Tank venting
2. Temperature.
3. WVO side still magically sucking air

My tank is in stainless steel under the car, and it has this tank vent mounted at the rear side of the tank, near the top, so when the 90degree bend is upwards, it has a couple of mm to the tank top. I tried rotating it 45 degrees on the test-drive today, without any luck. https://seatronic.no/vvs/toaletter/monteringsutstyr-toaletter/lufteventil-for-tank

Tank vent seen inside the tank:

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The tank under the car:

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It being -10C outside, this could obviousily be a bit of a problem. Before switching, I put my hand on the tank and the entire thing was nice and warm - at least warmer than my hand.

I had to drive for a good while to read 80C at the temp sensors on the two vm2 filter bases on the side of the car. The temperature drops quickly down to 60-70 when ideling, but when I kept it going at 1500rpm standing still I was reading about 70C.

I used 2 mins to do the switchover - 10s on/off vo in for the vegtherm to really get to work before I switched over. Then I idled for 10 minutes, last 2 mins keeping 1500 rpm. After that, I was able to drive pretty exactly 5mins before it died.

I have two pressure sensores tied in the system at the moment, one in the P port of the vm2 filter reading lift pump pressure, and one after the vegtherm just before the original filter. When I was ideling, they were both reading around 4,5psi, while I get 7psi running at diesel, so that seems like an acceptable difference due to the veg oil. When I was giving throttle in slight uphill, The pressure at the gauge just before the filter quickly dropped down to 1,2-1,5 while the pre filter was showing about 3. This tells me I need a stronger pump for the veg oil (and the diesel side) no matter where my veg oil problems might be.

When the truck finally died, I did as suggested by plantdrive, and jumped the lift pump for the veg oil while opening the drain valve on the fuel filter manager.. It seems like the filter house was empty - it took a while before anything came out, but when it did, it was a nice sizzling stream of veg oil. I double checked the drain valve from the bottom of the filter, and I was getting just as much veg oil as I usually do with diesel.

I´ve seen the same thing happen on another 6.5 before, due to restrictions in the fuel line/bad lift pump, which is why I´m thinking it might be the lp that is just to weak. 4,5 pre filter is anyway to little pressure for the IP to be happy, so I guess I should nudge it up a step anyway.