Anyone upgraded tank to pump lines?
 

Hi all,

After reading up a bit around the under specced fuel lines between the fuel tank to fuel pump, has anyone changed their fuel lines to the correct (Bosch) spec rather than the smaller Mercedes OEM lines?

Just wondering what people have done as my fuel pump will be demanding more fuel over the next few years after a few mods and I want to get the supporting tweaks in place first on a stock system.

Thanks in advance!

M1tch,

Please share your Bosch information. I've read a thread or two about insufficient flow volume for the OM606, and I'm wondering if it applies to my NA version.

I read in on here:

OM606 fuel supply issues

Apparenty the lift pump on the engine (both turbo and non turbo) is very strong and its causing such a vacuum owing to the smaller insufficiently sized pipes to draw air out of the diesel.

I am thinking about upgrading the long run from the tank to the lift pump to a larger diameter - I was also looking at adding in an electric fuel pump at the tank end as well.

What fuel pressure do we need?

Other diesels (Dodge Ram Cummins) have had problems with the injection pump going out because of poor cooling caused by undersized fuel lines and lack of lubrication caused by ULSD.

Here is 1 perhaps over kill solution: FASS Titanium Series Diesel Fuel Pump | FASSRIDE.COM

I have the Fass pump on my Dodge - problem solved. The stock Bosch pump is marginal at best. If I knew then what I know now, one of the first things I would have done on the Dodge is to install the Fass pump - not overkill in that application.

BTW - your explanation of the cause of failure on the Cummins is not quite right. The IP fails because they get insufficient fuel and therefore lack proper lubrication - IP cooling really isn't much of an issue according to the folks I spoke with at Fass. Anyhow, it's a GREAT fix and permanent. The installation is a bit of a chore but once done it's DONE.

The use of ULSD has little impact on IP life. I worked with early versions of that fuel and a combination of our testing and lubricity testing at the fuel manufacturers showed that there is still good lubricity in modern Diesel fuels. The longer hydrocarbon chains in Diesel (as compared to gasoline) maintain lubricity without regard to sulfur content. This is one of those urban myths that "everyone knows" but simply isn't accurate. I use on-road Diesel in the race truck when I could just as well pump cheaper non-road fuel into the 5 gallon jug that I fill from. The ULSD burns cleaner and I see no advantage to running dirtier fuel just because I can.

My initial thought is that our Mercedes' don't pass enough fuel to make use of the Fass but if interested you could call those folks - they were very helpful when I called.

Dan

McMaster-Carr

This is approved for biodiesel. Something like this is what comes with Elsbett Wvo kits. It's a big improvement over the old metal LiNes or small plastic lines.

I am in the UK so I will need to find a different supplier, our diesel is indeed low sulpher, however I am running some 2 stroke oil as premix with the diesel for added pump lubrication.

I am going to probably get an inline electric pump and a slightly larger diameter feed line from the tank. I don't think there are any intank pumps at all? I will look at some of the VWO kits as I know that the veg oil is thicker and so therefore needs slightly larger pipes etc - I might even run some veg oil in with some diesel at some point as well but not looking to run 100% veg oil.

Interesting comment on diesel lubricity. There was one "lubricity study" floating around that purported to find ULSD below the VP's requirements. My chosen fix is to run one of the older AirDogs bought before they started having build problems. I may add a sump because my fuel pick up is too high and draws air at slightly under 1/2 tank. The truck has been reliable now that most of the neglect has been taken care of. There was much more than anticipated.

I haven't needed to pay attention to how much fuel the SD needs. It runs fine in stock form & I haven't gotten around to tweaking.

When I first brought my truck home (sorry for the Cummins derail here) at 167K miles the truck ran out of fuel at about 1/3 tank - it was towed to my buddy Dave's shop here in town. They dropped the tank and found several issues with the pickup assembly, mostly a failure of a plastic part in the pickup assembly. We bought a MOPAR replacement assembly and purged the tank which had a bunch of what turned out to be algae in it. Since then both Dave and I run an occasional shot of algae killer thru our Diesel trucks (his is a Ford) and so far so good.

Dan

For my own selfish curiosity, I say go for it. I'd like to know the results either way.

Do we have any specs and calculations regarding how much fuel is called for? What is the stock fuel pressure and injector flow?

All of these points I am working on, although I know that the injectors should fire at around 135 bar but the stock feed pressure is at around 14psi - its why I would need to look into getting a rising rate regulator if I were to use an electric pump to bring it down from the higher pressure most pumps run at.

I believe there are also upgrades you can do on the pump around raising the internal pump pressure to increase the fill rate of the elements which I might also look into.

Edit: It looks like the overflow valve can be modified to allow for a properly pressurised pump which might also fix the vacuum issue on the intake:

http://www.superturbodiesel.com/std/showthread.php?tid=2774

I would really like to add an electric pump at the tank to push fuel forwards, and also flow said fuel forward in an appropriate sized fuel line. It seems that if you could feed the stock lift pump around 10-15 PSI that it would certainly help things by significantly reducing the load on the lift pump and could help improve the fill rate at the elements. If going this route, I would also like to add a better filter setup to the equation.

The ideal solution to me would be to simply bypass the entire stock filter and lift pump setup and run an electric pump from the tank, through a "real" diesel filter bank setup (something like 20, 5, and 1 micron filters), and directly into the IP. This, however, creates real complications on the W210 due to the thermostat and Shut Off Valve (I'm sure if you bypass both of these it will throw codes).

On my 85 300D 617.952, I have on the fuel filter a water clear return to tank sight window. The fuel system is tight and there are no air bubbles when idling. If I rev the engine hard to 3500 rpm from idle, I can see what appears to be bubbles. I always wonder if that is due to the long run of the (restrictive) 8 mm fuel line. It'd be interesting to rig up a USB camera to look at the clear line while driving under high load conditions.

Nice find. So where abouts is this banjo bolt in question on the IP? Seems to follow the rule to look at the simple things first, eh?