Lift Pump - PeachParts Mercedes-Benz Forum

hawthorne90250 · #1 07-05-2012, 01:36 PM

Hi
I have developed a fuel problem, Car will use what's in filter then stall out. I have checked everything. It already has new fuel lines, Tank filter, Primary and secondary filters. checked hard lines from/too tank are open.
The latest thing i tried was remove fuel line from primary filter to primer pump and checked for suction when pumping the hand primer, it had good suction. i then started the car and removed the same line with car running and it had no suction. the fluid in the primary filter drained back to tank and when i reattached hose the filter did not refill (engine still running) . The only way to refill primary filter was with primer hand pump. I suspect lift pump is not working. has this happened to anyone?
Thanks

kerry · #2 07-05-2012, 01:53 PM

yes they do fail. I think there is a rebuild kit available somewhere if my memory serves me correctly. Perhaps someone else knows where to buy the kit instead of a whole new pump.

Diesel911 · #3 07-05-2012, 03:54 PM

Our own Parts Seller sponser sells the Valve kits. However, the Valve Kit lacks the little O-ring that you will also need.

You will have to look up that in the DIY section as I am on a Library Computer and do not have my Notes.

Stretch · #4 07-05-2012, 04:25 PM

I haven't done the lift pump on my MW IP yet but it looks pretty much of the same family - here's the pump from the M / RSF IP similar fitted to the non turbo OM617s and OM616s

http://www.peachparts.com/shopforum/diesel-discussion/294499-refreshing-fuel-pump-om617-european-spec-%96-non-turbo.html

If your pump isn't exactly like the one shown in the thread linked above the information shown should get you most of the way to the finish line...

hawthorne90250 · #5 07-05-2012, 08:26 PM

Quote:

Originally Posted by Diesel911

Our own Parts Seller sponser sells the Valve kits. However, the Valve Kit lacks the little O-ring that you will also need.

You will have to look up that in the DIY section as I am on a Library Computer and do not have my Notes.

I just took apart and cleaned a spare one i had, i cannot see any O-ring. Mine has a roller on it what it rides on the IP cam. Not like Army's pump http://www.peachparts.com/shopforum/diesel-discussion/294499-refreshing-fuel-pump-om617-european-spec-%96-non-turbo.html

qwerty · #6 07-05-2012, 09:02 PM

Quote:

Originally Posted by hawthorne90250

I just took apart and cleaned a spare one i had, i cannot see any O-ring. Mine has a roller on it what it rides on the IP cam.

The o-ring is located under the roller assembly. It seals the shaft. If the o-ring was leaking bad enough for the pump to fail, you would likely have diesel fuel overflowing from the crankcase.

Quote:

Originally Posted by hawthorne90250

The latest thing i tried was remove fuel line from primary filter to primer pump and checked for suction when pumping the hand primer, it had good suction.

Suction is only half of the equation. If the intake (suction) valve does not close, you willl have great suction but no pressure on the discharge stroke.

hawthorne90250 · #7 07-05-2012, 09:03 PM

Quote:

Originally Posted by qwerty

The o-ring is located under the roller assembly. It seals the shaft. If the o-ring was leaking bad enough for the pump to fail, you would likely have diesel fuel overflowing from the crankcase.

Thanks
How do you remove the roller assembly?

qwerty · #8 07-05-2012, 09:36 PM

Quote:

Originally Posted by hawthorne90250

Thanks
How do you remove the roller assembly?

Relieve the pressure on the roller and remove the snap ring. (With the piston spring removed, there should not be any pressure.)

hawthorne90250 · #9 07-06-2012, 02:30 PM

Well, I took off my lift pump and took it apart. The Plunger was frozen, and i had to remove the cam to beat it out. will put on spare tomorrow and am sure it will solve fuel problem.
Thanks

Diesel911 · #10 07-06-2012, 08:49 PM

Quote:

Originally Posted by hawthorne90250

Well, I took off my lift pump and took it apart. The Plunger was frozen, and i had to remove the cam to beat it out. will put on spare tomorrow and am sure it will solve fuel problem.
Thanks

What do you think caused the Plunger to get stuck?

hawthorne90250 · #11 07-07-2012, 12:22 PM

Quote:

Originally Posted by Diesel911

What do you think caused the Plunger to get stuck?

Hi
By Plunger i mean the Little round piston that moves back and forth to compress the fuel. The problem was caused by me leaving bio-diesel in the system and then parking the car for a year without using it . the tank was full off black fungus as thick as a tar ball. I had to remove and clean tank ,clean lines, dissemble injectors, replace all filters and rubber lines,replace fuel sender which was only 2 years old but the center shaft had dissolved. I just hope i did no damage to IP. The bio-diesel was pretty corrosive when left setting like this.

Diesel911 · #12 07-07-2012, 02:08 PM

Quote:

Originally Posted by hawthorne90250

Hi
By Plunger i mean the Little round piston that moves back and forth to compress the fuel. The problem was caused by me leaving bio-diesel in the system and then parking the car for a year without using it . the tank was full off black fungus as thick as a tar ball. I had to remove and clean tank ,clean lines, dissemble injectors, replace all filters and rubber lines,replace fuel sender which was only 2 years old but the center shaft had dissolved. I just hope i did no damage to IP. The bio-diesel was pretty corrosive when left setting like this.

I would call that a Piston. Yes, that is one of the Things that can cause the Piston to stick; also rust.

In the Pic one of the Arrows Points to where the O-ring is supposed to go; in the Hole that the Push Rod Goes into is a internal Groove for the O-ring.

hawthorne90250 · #13 07-07-2012, 02:54 PM

Quote:

Originally Posted by Diesel911

I would call that a Piston. Yes, that is one of the Things that can cause the Piston to stick; also rust.

In the Pic one of the Arrows Points to where the O-ring is supposed to go; in the Hole that the Push Rod Goes into is a internal Groove for the O-ring.

I had a spare one i cleaned up and just installed, and the difference is amazing. no more sluggish takeoffs from a standstill, for a N/A its zooming along. in the 7 years i have owned this car this is the fastest it has been. suspect its been bad for a while and finally gave up the ghost . Anyway i am about to bring it from Hawthorne up the 405 to Marina Del Ray.

mach0415 · #14 07-07-2012, 08:19 PM

Question 1 : In the event that I were to suspect I had a bad lift pump, resulting in a crank-no-start issue, could I manually keep the engine running by pumping the primer pump?

Question2 : If I had a boost gauge installed, could I determine if I had fuel starvation or an inlet restriction by observing boost pressure?

My assumption is yes to both.

qwerty · #15 07-07-2012, 10:55 PM

Quote:

Originally Posted by mach0415

In the event that I were to suspect I had a bad lift pump, resulting in a crank-no-start issue, could I manually keep the engine running by pumping the primer pump?

It would depend on what had failed. The hand pump, for example, uses the same valves as the engine-driven pump. A stuck or leaking valve will affect both pumps.