Anyone upgraded tank to pump lines? - Page 2 - PeachParts Mercedes-Benz Forum

m1tch · #16 05-13-2015, 03:04 AM

Quote:

Originally Posted by treetops

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?

I believe its on the return line to the tank - my guess is that it works like a restrictor meaning that the pressure in the pump overall reaches a set level and then the pressure is released - I think the mod changes this so that the spring and internals are stronger so the internal pump pressure needs to increase to a higher level before it releases.

I have seen a seller on superturbodiesel who has made up modified versions of them, although the specs are secret (makes sense) but I am guessing there is an uprated spring in there.

Maxbumpo · #17 05-13-2015, 10:01 AM

Quote:

Originally Posted by m1tch

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.

Please take some before/after measurements of 0-60 time or some other objective measurement and let us know the results. Do you keep good records of your fuel consumption? That would be another nice test, but that one is more susceptible to changes due to the driver. I'm also tempted to try this. I had a small leak allowing air into the fuel circuit at the fuel thermostat, really killed the power at high RPM.

Simpler=Better · #18 05-13-2015, 10:05 AM

You can't have too much fuel available. In my daydream build I plan on running 1/2" fuel lines everywhere.

Maxbumpo · #19 05-13-2015, 10:14 AM

Quote:

Originally Posted by m1tch

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.

Reading that thread yesterday and re-reading today, my subconscious worked on this problem overnight and presented a possible solution this a.m.

The STD post touches on adding some type of "shock absorber" or anti-hammer device to smooth out the pressure drops caused by the lift pump. In other words, if there was a flexible-walled reservoir to hold some fuel that could be drawn down by the intake of the lift pump without a big pressure drop that draws out the entrained air (which does not re-absorb into the fuel and is the basic problem we are trying to solve).

I'm wondering if using the "cigar" hose from a 123 diesel to replace that length of fuel line from the steel supply line to the fuel thermostat would provide enough of a buffer. My theory is that if the cigar hose was meant to smooth pressure spikes on the down-stream side of the 123 system, maybe it can also reduce pressure drops on the intake side.

Cloudsurfer · #20 05-13-2015, 11:48 AM

Quote:

Originally Posted by Maxbumpo

Reading that thread yesterday and re-reading today, my subconscious worked on this problem overnight and presented a possible solution this a.m.

The STD post touches on adding some type of "shock absorber" or anti-hammer device to smooth out the pressure drops caused by the lift pump. In other words, if there was a flexible-walled reservoir to hold some fuel that could be drawn down by the intake of the lift pump without a big pressure drop that draws out the entrained air (which does not re-absorb into the fuel and is the basic problem we are trying to solve).

I'm wondering of using the "cigar" hose from a 123 diesel to replace that length of fuel line from the steel supply line to the fuel thermostat would provide enough of a buffer. My theory is that if the cigar hose was meant to smooth pressure spikes on the down-stream side of the 123 system, maybe it can also reduce pressure drops on the intake side.

It would likely help, but the real solution is the proper size fuel line from tank to lift pump.

Diesel911 · #21 05-13-2015, 09:22 PM

I don't know on the OM606 but on the 617.952 there is a flow spec for the Fuel Supply/lift pump in the Factory Manual.

m1tch · #22 05-14-2015, 03:00 AM

Quote:

Originally Posted by Maxbumpo

Please take some before/after measurements of 0-60 time or some other objective measurement and let us know the results. Do you keep good records of your fuel consumption? That would be another nice test, but that one is more susceptible to changes due to the driver. I'm also tempted to try this. I had a small leak allowing air into the fuel circuit at the fuel thermostat, really killed the power at high RPM.

My car is a project car and will be used to do 1/4 mile drag runs - planning to do mods in stages with the differences noted at each stage as well as the drag time I was able to get with each setup.

I might look to doing all of the usual mods to the car, eg air filter/exhaust/EGR delete/resistor fueling mods. After I have a baseline for those mods upgraded on the stock setup using the stock fueling I will then look into modding the fuel supply system.

I also had an idea as well around the fuel system, the OM606 doesn't have any form of primer pump, on other engines there is usually a primer bulb of some sort - perhaps this could be used inline with the fuel supply to act like a fuel damper as well?