No power - Page 2 - PeachParts Mercedes-Benz Forum

Alec300SD · #1 04-16-2020, 10:36 PM

Could be the seals on the hollow bolt for the secondary fuel filter.
It will take a crush washer and an o-ring if it is an "01" head, or two o-rings if it is an "02" head.

Other possibilities where air incursion can occur are the primer pump, or the lift pump itself.
The lift pump has a small internal o-ring that does fail over time, and/or the internal check valve can fail.

cbum33 · #2 04-17-2020, 11:12 PM

I have rebuilt the lift pump and installed a new Bosch primer pump. The only line I haven't changed is the line from the lift pump up to the filter but again I don't see air in the line to the injection pump its only in the return line.

I also replaced the o ring on the filter bolt and have changed all the crush washer on the fittings that hold the fuel lines on the pump and filter housing.

When I start the car first thing when cold it blows white smoke till it gets warmed up. Then once it is warmed up it starts to drive better. I have checked the compressions all of which were 350 and greater. Valves have been adjusted. I did check the 0-60 time and its around 22 seconds assuming this is due to the air in the fuel but giving as much info as I can.

Thanks

Diesel911 · #3 04-27-2020, 11:55 PM

Quote:

Originally Posted by cbum33

I have rebuilt the lift pump and installed a new Bosch primer pump. The only line I haven't changed is the line from the lift pump up to the filter but again I don't see air in the line to the injection pump its only in the return line.

I also replaced the o ring on the filter bolt and have changed all the crush washer on the fittings that hold the fuel lines on the pump and filter housing.

When I start the car first thing when cold it blows white smoke till it gets warmed up. Then once it is warmed up it starts to drive better. I have checked the compressions all of which were 350 and greater. Valves have been adjusted. I did check the 0-60 time and its around 22 seconds assuming this is due to the air in the fuel but giving as much info as I can.

Thanks

Tell me what you did when you rebuilt the Fuel Supply/Lift Pump. Mainly did you install a new tiny O-ring in the attached picture that the orange arrow points to?
I am asking this because there is a fuel supply/lift pump valve kit that does not come with a new O-ring.

Also white smoke can be Coolant or late fuel injection pump timing. If it is coolant it will smell like the antifreeze if it is Fuel it will smell like fuel.

Alec300SD · #4 04-18-2020, 12:04 AM

If you have bubbles in the return line, you have air incursion into the high pressure circuit of the IP.
A tight fuel system will have no air in the return line even after sitting for weeks at a time.

Air incursion can be intermittent, the air being drawn in via the high suction of the lift pump running at speed.
You won't notice the slight engine miss from a little bit of air in the IP at speed.
However, you might notice a rough idle after a hard run and/or a smoky start (unburnt fuel at startup) the next day.

Double check your rubber hoses connected to the primary fuel filter.
If you can rotate the hoses when you grasp them firmly by hand or with pliers, then air can potentially be entering through that union.

Also, try running a mini-tank under the hood.
This is to rule out air incursion from the fuel tank to the primary fuel filter.
You can have pinhole leaks in the hard lines, oftentimes from hidden corrosion under the rubber vibration isolation clamps for the fuel lines.

Diesel911 · #5 04-27-2020, 11:49 PM

Quote:

Originally Posted by Alec300SD

If you have bubbles in the return line, you have air incursion into the high pressure circuit of the IP.
A tight fuel system will have no air in the return line even after sitting for weeks at a time.

Air incursion can be intermittent, the air being drawn in via the high suction of the lift pump running at speed.
You won't notice the slight engine miss from a little bit of air in the IP at speed.
However, you might notice a rough idle after a hard run and/or a smoky start (unburnt fuel at startup) the next day.

Double check your rubber hoses connected to the primary fuel filter.
If you can rotate the hoses when you grasp them firmly by hand or with pliers, then air can potentially be entering through that union.

Also, try running a mini-tank under the hood.
This is to rule out air incursion from the fuel tank to the primary fuel filter.
You can have pinhole leaks in the hard lines, oftentimes from hidden corrosion under the rubber vibration isolation clamps for the fuel lines.

In order to get air into the high pressure area (the Elements on out to the Injectors) the air has to be present in the low pressure fuel supply area of the inside of the fuel injection pump.

cbum33 · #6 04-29-2020, 07:24 PM

Diesel911 when I rebuilt the pump I am pretty certain I replaced that o ring and the valves. I bought the rebuild kit from a Bosch dealer for around $20. Before rebuilding the pump I had air in the return line pretty much all the time unless I clamped off the return line. After rebuild there is still a few air bubbles in the return line at idle but no where near the same amount. It's not till you bring the rpm up does the return line seem to have a ton of air. The car will still run fine once you get the rpm up high enough. It is just slow and sluggish till that point which is usually around 15-20MPH.

I did just put a fuel line and jar of fuel to the lift pump to test if I was getting air from the tank and the air was still there.

I am willing to try anything. I got a quote for $200 to have the injection pump tested and $1200 to rebuild it. I am only seeing used ones with no known history other than worked when pulled for 5-600. Just feel like everything I have done it seems like the injection pump is the issue but then also keep reading that these VERY RARELY fail so not sure what to do next.