Adding electric fuel pump to OM606 car (or OM603 or earlier too) - PeachParts Mercedes-Benz Forum

Cloudsurfer · #1 04-01-2015, 05:56 PM

I've been thinking about this, especially for those of us who run other fuels than straight road diesel, and it sure seems like it could make a lot of sense.

You can't even find a suction lift pump for a Cummins truck anymore, and all the OEMs gave up using suction lift pumps long ago, so what about the viability of either bypassing the suction lift pump on our cars, or simply adding a pressure fuel pump (ideally in the tank) to help things?

This could also have the benefit of making it feasible to add better fuel filtration (perhaps a filter or two mounted in the trunk?).

I assume that the Shut Off Valve can't be bypassed without pissing off the computer, and I don't know whether the SOV would like having positive pressure applied to it.

My inclination would be to simply have an electric pump help the suction lift pump and leave everything else alone. The question then becomes, what flow rate and pressure should said pump output?

Thoughts?

KarTek · #2 04-01-2015, 07:23 PM

Couple thoughts... I have a Powerstroke diesel electric fuel pump that I have run on my car as an experiment. The plan was to install it in the rubber section of hose under the tank, controlled by a relay and a oil pressure switch so it doesn't run if the engine quits.

The car ran fine but the thing I noticed was that the fuel oozed out of the electrical connector for the SOV. Either the valve is worn out or it isn't designed for pressure, only vacuum.

mach4 · #3 04-01-2015, 07:41 PM

I think using an electrical pump could be an appropriate addition to the fuel system. I don't know of an aircraft that doesn't have a "boost" pump which is normally turned on for starting, taxi and takeoff. After that it's turned off and the engine driven pump is used. Provides an extra margin for error as well as a fail-safe system for in-flight pump failure.

I believe that a low pressure (4-6 pounds or so) pump would not harm the lift pump or have an adverse effect on the fuel system.

dieselbenz1 · #4 04-01-2015, 07:49 PM

I run a diaphragm pump 9 psi in series with the. Fuel pump on my old Chevy just for starting as I only use it every several months. Once the truck starts I turn off the electric pump. Works great. A similar setup will work fine withe the lift pump on a diesel.

GregMN · #5 04-01-2015, 07:58 PM

Find someone at your parts store who knows what a carburetor is.
Ask them for an electric fuel pump for a carbureted fuel system.
It should pump at 3 to 5 psi and be a free flow design so that fuel can flow through it when it is off.
It should cost less then $30.

I permanently installed one on my W210 606 after the first time I worked on the fuel system to help prime the system. I installed it on the fuel source line at the fire wall. That was 7 years ago. I only turn it on to prime the fuel system after working on it. It was $30 well spent.

I just re-installed a 603 IP on my 606. I connected all the fuel lines and turned on the pump. I had fuel out of the hard lines at the injectors after 20 seconds of cranking.

TnBob · #6 04-01-2015, 07:59 PM

Wouldnt be good to exceed the normal input pressure to the IP or at least if so not by very much.
Return hose would deal with the excess if you got it really wrong.

Cloudsurfer · #7 04-02-2015, 12:11 AM

Interesting thoughts here guys....

Yes, all aircraft (both pistons and turbines) have redundant fuel pumps (well, redundant EVERYTHING), and it's for good reason.

Is 3-5 PSI enough here? I had figured 30+ PSI? The other question is how much flow is required?

From a performance aspect, I'd think feeding the injection pump straight from an electric, pressure fuel pump would be an advantage, but while one could easily just remove the vacuum lift pump from the equation, I'm guessing that leaving the SOV just hanging there with no fuel flow through it would trigger codes.

Ideally, you'd have sufficient pressure, with sufficient flow, that it would require a return line and a regulator.

Here's an interesting article I came across, which discusses this (and more):

OM606 fuel supply issues

biopete · #8 04-02-2015, 11:29 AM

I've used these on benzs for years. Precision Fuel Pumps E16087 - Electric Fuel Pump | O'Reilly Auto Parts

Pass through when not on and easily available any where. Part e16087. My 2000 Chevy 6.5 diesel uses same pump as oem lift pump but it has screw fittings

You can just put it under the hood and jumper it to the battery when you need it. Or wire it up to the ignition.

strelnik · #9 04-02-2015, 11:54 AM

Quote:

Originally Posted by dieselbenz1

I run a diaphragm pump 9 psi in series with the. Fuel pump on my old Chevy just for starting as I only use it every several months. Once the truck starts I turn off the electric pump. Works great. A similar setup will work fine withe the lift pump on a diesel.

by any chance, is this engine an older 6.2L diesel?

Cloudsurfer · #10 04-03-2015, 06:46 PM

Quote:

Originally Posted by biopete

I've used these on benzs for years. Precision Fuel Pumps E16087 - Electric Fuel Pump | O'Reilly Auto Parts

Pass through when not on and easily available any where. Part e16087. My 2000 Chevy 6.5 diesel uses same pump as oem lift pump but it has screw fittings

You can just put it under the hood and jumper it to the battery when you need it. Or wire it up to the ignition.

Interesting. Is this just to help bleeding?

Drago · #11 04-03-2015, 06:53 PM

lift pump for a 6.5 Detroit should work. the OEM isn't the best, they tend to fail annually

Cloudsurfer · #12 04-04-2015, 10:41 AM

How does this look? The 4-6PSI range should be good, and I'd think 35GPH is enough?

Weber Redline Carburetor Universal Inline Low Pressure Fuel Pump 4 6 PSI 35GPH | eBay

Ideally to me (and based on the post that I linked to from superturbodiesel), you'd want this just below the tank, BEFORE it goes into the hard line up to the front of the car (due to this hard line allegedly being under-sized).

Which then brings up the issues of mounting said pump, and engineering an appropriate relay into the equation such that it engages upon the key being in position II, but that it would shut off if you were to get into an accident.

ROLLGUY · #13 04-04-2015, 11:17 AM

I used to get pumps from the Zone that worked great as a priming pump, or as an added "helper" pump. I believe the brand was Master, and they had pumps specifically for Diesel in 5/16, and 3/8 hose size with a PSI rating around 6. Oddly enough, I was using these around the time when the Lovecraft WVO system was popular, and their kit used the same pump. I would think that a pump like this would work in tandem, for priming, or as stand alone to replace the factory lift pump. Either way, I would put it on a separate lighted switch so you know when it is activated.

ROLLGUY · #14 04-04-2015, 11:23 AM

Just found these:
http://www.amazon.com/Airtex-E8251-Universal-Electric-Applications/dp/B0027I88VQ

New Universal Electric Fuel Pump Gas Diesel Marine Carbureted Ref E8016S | eBay

funola · #15 04-04-2015, 12:01 PM

I don't think these electric solenoid pumps can replace the mechanical lift pump. It may barely put out enough pressure to allow the engine to start and run, but probably not enough to meet high power / high rpm demand. If you did find a suitable pressure/volumne electric pump, what are you going to do with the mechanical pump? It will burn out without fuel running through it.