PeachParts Mercedes-Benz Forum - Engine won't turn over- injection pump?

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Engine won't turn over- injection pump?

so my poor sad 1982 300td has been sitting in my driveway since july. quick recap: boyfriend put some bad biodiesel into the diesel tank ( i run a two tank wvo system) The car hated it, it puttered all the way to the gas station, i filled it up, it ran fine all the way home then it wouldn't start again.

I drained the diesel tank, filled it with fresh diesel, changed all the fuel filters, and replaced the primer pump which also stopped working. No good, so recently (this past week) i installed an auxiliary fuel pump on the diesel side to bypass the lift pump completely. It still won't start.

When i crack the injectors, no fuel is coming out as i try to turn the car over. the new pump is working and there is fuel in the fuel filter. i cracked the return line coming out of the injector pump and no fuel is pumping through it.

so does this sound like a clogged IP or a bad IP? I'm fearing the worst here, i'm gonna have my mechanic check it out, but i always like to ask fellow MB owners for suggestions and opinions. thanks!!

It does sound like something is wrong with the IP. When you pump the primer, can you get fuel to flow out the return line? (I'm pretty sure it should, but I'm not certain).

well we no longer use the primer as the auxiliary fuel pump bypasses the lift pump which houses the primer pump.. so...

Could you clarify " crack the injectors" exactly ?

Quote:

Originally Posted by swarda (Post 2137079)

so my poor sad 1982 300td has been sitting in my driveway since July. quick recap: boyfriend put some bad bio-diesel into the diesel tank ( i run a two tank WVO system) The car hated it, it puttered all the way to the gas station, i filled it up, it ran fine all the way home then it wouldn't start again.

I drained the diesel tank, filled it with fresh diesel, changed all the fuel filters, and replaced the primer pump which also stopped working. No good, so recently (this past week) i installed an auxiliary fuel pump on the diesel side to bypass the lift pump completely. It still won't start.

When i crack the injectors, no fuel is coming out as i try to turn the car over. the new pump is working and there is fuel in the fuel filter. i cracked the return line coming out of the injector pump and no fuel is pumping through it.

so does this sound like a clogged IP or a bad IP? I'm fearing the worst here, I'm gonna have my mechanic check it out, but i always like to ask fellow MB owners for suggestions and opinions. thanks!!

The aux pump you are using must reach 12 PSI.
Need pictures of your fuel plumbing under the hood.

:EDIT: the following does not apply, further data in post# 6.
There are two things that can stop fuel coming out of the injector pump bypass valve.
* Plugged fuel tank screen.
* Plugged secondary filter.

Nice talking with you on the phone

More data for members
The current aux pump is 5-9 psi and runs with any key on position.
They will crack the injection pump bypass valve (between block and IP) to check for fuel flow.
The factory fuel tank is WVO, aux tank is a plastic 7 gallon filled with diesel and bio-diesel, (no screen).
They will try running off a temporary quart fuel bottle under the hood = bypass all fuel tanks.

So the aux fuel pump at 5-9 psi is not enough to open the overflow valve.

May be the real Fuel Supply pump needs to be taken apart and cleaned.

Time to go back to basics...........

Do you have installed:

a known good primer pump?
a known good primary filter?
a known good secondary filter?

Also, did you fill the secondary filter
prior to installing?

have you checked to see if Bio has degraded
the rubber lines?

Have you thought about throwing that system
in the dumpster after you get the car running?

Quote:

Originally Posted by JackG (Post 2137498)

Filters are new and full.
Rubber lines are OK.

LOL, can't answer the last question.

Trace the fuel. Check the fuel as it goes into the filter. is there pressure? As it comes out? if there is then I would crack the fitting at the IP and let it drip some to get the air out. Then loosen the fuel lines at the injectors, and have someone crank the car and see if you are getting fuel to the injectors.
Maybe the banjo fitting at the IP is clogged with garbage?
I would not worry so much about the return, until I kow why I am not getting any fuel to the IP

Quote:

Originally Posted by blackestate (Post 2137657)

If there is no fuel coming out the injection pump bypass valve hole (between block and IP) = no fuel flow into the ip.