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  #1  
Old 08-30-2018, 10:49 AM
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Injector pump pressure

1995 E300D, 290,000 miles, loss of power after replacing a few fuel lines from the tank to the engine.

The shop is telling me that the IP may not be pushing enough pressure to the injector to #1 cylinder. Does anyone know what the IP is supposed to be putting out to the injectors? Spray pattern looks good.

Hopefully I'm not looking at replacing the IP or having it rebuilt.

Thanks,

Len

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1960 190D (college car), gone
1995 E300D, 325 k
2019 LEXUS UX 250h (spouse mobile)
2003 Nissan Frontier Crew Cab
2007 Jeep Grand Cherokee Overland 3.0L MB diesel, 185K
1978 GMC Classic Motor Home
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  #2  
Old 08-30-2018, 12:09 PM
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The pressure delivered to the injector is set by the pop pressure. The pump is capable of developing several thousand PSI of pressure if dead-ended.

I'd be extremely surprised if replacing fuel lines caused an IP failure. If you're curious, connect a known-good injector to a spare hard line and crank the engine over. Once the air is burped out of the line, you should see it firing the injector.

Being an OM606, be on the lookout for air ingress. There are several O-ring connections on various fittings that can leak air and cause all sorts of issues. Have the fuel filters been changed recently?
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Old 08-30-2018, 06:13 PM
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Thanks for the reply.

The fuel filters have not been touched.

We just changed the lines coming from the tank going to the filters and one main return line.

I got it back and noticed a significant loss of power and took it back.

They have bled down the system several times with the same results.
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1960 190D (college car), gone
1995 E300D, 325 k
2019 LEXUS UX 250h (spouse mobile)
2003 Nissan Frontier Crew Cab
2007 Jeep Grand Cherokee Overland 3.0L MB diesel, 185K
1978 GMC Classic Motor Home
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  #4  
Old 08-30-2018, 06:21 PM
Diesel Preferred
 
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Location: Charleston SC
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I'll bet you've got an air leak at any of the six or seven joints that use o-rings. The o-rings in that car are a known weak point (most or all of the connections between the injection pump and the fuel filter housing use these o-rings). Standard procedure for me is to replace ALL of those o-rings if even one appears to be leaking, because they can cause so much trouble including exactly what you are describing (loss of power and shop can't bleed the air out of the system).

The intake manifold will need to come off to do this work. If money is not too tight, and your old fuel lines are no longer clear (the lines between injection pump and the fuel filter holder) then in addition to all the o-rings, replace all those clear lines.

The injection pump and fuel holder needs to be really clean and stay clean during the work, so there is no contamination of the fuel system with dust or grit, which can damage the injection pump and the fuel injectors.
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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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  #5  
Old 08-30-2018, 06:23 PM
Diesel Preferred
 
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Location: Charleston SC
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DO NOT let the shop replace the injection pump, they are very robust and last the life of the engine if properly cared for. If the shop comes to that recommendation and won't try anything else, find another shop. Better yet, change the o-rings yourself, easy to do with the info and guidance from this list, will probably take you most of a day if you're handy with tools and able to follow instructions.
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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC
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  #6  
Old 08-30-2018, 06:48 PM
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Quote:
Originally Posted by b52rule View Post
Thanks for the reply.

The fuel filters have not been touched.

We just changed the lines coming from the tank going to the filters and one main return line.

I got it back and noticed a significant loss of power and took it back.

They have bled down the system several times with the same results.


There is also a screen in the Fuel Tank and the Fuel Tank has a vent.


On the side of the Fuel Injection Pump is the Fuel Supply/Lift Pump that sometimes needs rebuilding.
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Old 09-03-2018, 01:58 PM
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Standard approach would be to have a visable piece of fuel line in the injection pumps output. To verify no air content. No air? What fuel pressure is present in the base of the injection pump should be next.

Also any time any form of fuel supply issue potential is identified. A change of fuel filters is good practice. If they make no difference put into fuel proof containers and kept in the trunk. For emergency spares is not a bad practice. Plus the tools to change them. You can bypass that if you test for fuel pressure and have adequate.

In your case especially if there is no air present in the output of the injection pump filters should be checked . Too many times the problem just being dirty fuel filters resulting in a long drawn out search for the issue has occurred. Sounds like you just have the all too typical issues of air entering into the system or a fuel starvation issue.

Initially I would check their fuel line work for any partially collapsed or typically kinked lines. They messed up something somehow. Or if they diagnosed the problem perhaps got it wrong. You can almost always rule out coincidence in these situations.

My guess is they did not even do the preliminary tests to identify the real problem. When you took the car back. Injection pumps will not function normally with incoming air in the fuel present . Or the fuel is supplied at inadequate pressure. This indicates the volume is possibly substandard as well.

A systematic approach is far better than just guessing. Why did you originally take the car in for fuel line work? What was the issue at that point. There are some questions in my mind as normally you do not use a garage without an issue being present. If it was low power before you took it in is going to change some things. Or perhaps not depending what it was..

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