Author Topic: 300SD Power Loss | Fuel Delivery Issue?  (Read 557 times)

SuitGuy

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300SD Power Loss | Fuel Delivery Issue?
« on: 20 July 2021, 06:03 PM »
Hello all! My 1980 OM617 seems to greatly dislike hills and anything requiring power. I believe it is a fuel delivery issue but I am unsure where to begin. I have already replaced my filters, return lines, and the main fuel line to the injector pump. Is it likely I have a pump beginning to kick the bucket?

Description of the issue:
You're driving down the road at highway speeds (55 mph) and you come to the ever so slightest, barely perceivable incline when suddenly the engine decides that you don't need power. It'd rather just lag like you're dragging a doublewide.
You put your foot to the floor. The engine roars to half throttle then falls flat on its face.

I am currently in the process of securing two new crush washers for the ALDA banjo bolt, as they had been replaced with a lock washer by the previous owner. This is an issue that has developed over the course of a month, so I doubt it will cure my power loss. Any and all wisdom is appreciated.
Kindly, Suitguy
Beige 1980 300SD

SuitGuy

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Re: 300SD Power Loss | Fuel Delivery Issue?
« Reply #1 on: 21 July 2021, 04:08 PM »
Update: I have plumbed in an electric pump and this has not solved the issue. The crush washers are on their way. Could this be in the transmission?
Beige 1980 300SD

Alec300SD

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Re: 300SD Power Loss | Fuel Delivery Issue?
« Reply #2 on: 21 July 2021, 05:48 PM »
Low power is most likely due to lack of boost signal to ALDA.
Without the boost signal, the ALDA will limit fuel delivery, and the car will behave like a NA OM617.
79 W116 300SD 'Stormcloud' new as of 10/22/2017
78 W116 300SD 'Desert Rose' new as of 01/26/2014
83 W126 300SD 'Rena 2.0' with engine from 82 W126 300SD Rena' (SOLD and crushed 11-20-2017)

SuitGuy

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Re: 300SD Power Loss | Fuel Delivery Issue?
« Reply #3 on: 23 July 2021, 05:43 PM »
Thank you, but sadly this has not resolved my power loss. My next steps are replacing the tank screen and hose as well as installing new tips on the injectors. I did a transmission fluid swap in case it was in the transmission; no improvement so far. It seems to drive fine, but it behaves like the governor has kicked in once it comes up on a slight incline or is throttled beyond a certain point. It's bizarre.
Beige 1980 300SD

SuitGuy

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Re: 300SD Power Loss | Fuel Delivery Issue?
« Reply #4 on: 24 July 2021, 04:22 PM »
Wonderful news! After a valve adjustment and bypassing the ALDA blowoff valve, all power has been restored. I am a poor scientist, but a subpar mechanic. Future plans include securing a new blowoff valve and replacing the old one. Thank you all for your wisdom!
Kindly,
SuitGuy
Beige 1980 300SD