I have a transplanted OM617 turbo into a 1988 4runner.
I have had the pump updated to 7.5mm elements from a reputable source using Dieselmeken elements. Injectors cleaned and balanced by greaser, valves adjusted with plenty of clearance.

Before the upgrades, the engine was running smoothly. Now, it starts fairly easily but immediately begins loping or surging at idle. It seems to be fine at higher RPM. I have adjusted idle speed, and adjusted the rack damper several times with no improvement. The lope is approx every second. The rack damper adjustment can sometimes slow down the frequency momentarily - but it always returns. The longer I let it idle, the more severe the lope. This isn't the typical idle shake that many threads exist for, this is severe. My working theory is the idle governer is improperly set, but that is an invasive job to undertake. Looking for suggestions on what i might have overlooked.

there are post out there that claim that without the proper cigar hose on the 617 it will cause rough idle

i dunno


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Good point. Try that first.

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Jim

You should be speaking with those who rebuilt the Pump.

What about your Fuel Pressure Relief/Overflow Valve? Go through the expense of having the Pump rebuilt and use the old one?

Did you send the Fuel Supply/Lift Pump with it to be rebuilt?

Then there is basic stuff like air getting into the fuel going into the Fuel Injection Pump.

When you say something is upgraded it implies that there was something wrong with the original equipment and that is not the case. The old Fuel Injection Pumps are extremely trouble free.
An upgrade would be something like Viton O-rings and so on.

The Super Tubo Diesel site would likely yield more expertise.

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84 300D, 82 Volvo 244Gl Diesel

IIRC from a recently viewed YouTube video (forgot to bookmark it), you need to retard the timing just a tad from stock when using a MW pump with 7.5 elements.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

You might ask Eric Persson at Dieselmeken. I dropped my Dieselmeken pump in and once I got the air out of the system it runs like a watch (yes there IS some ticking but all that is normal!). But seriously, check with your rebuilder first then ask Eric.


Dan

Update to this issue:
The idle surge is only present when the engine is cold.
As soon as the engine warms up (160F or greater) the idle is perfect.
Timing is verified via drip method dead on 24 degrees, also tried slightly advanced and retarded, made no difference.
Replaced rack damper - tried several points of adjustment. All the way out I can get it to surge at all engine temps. After engine is warm, I adjusted it in just until the idle smoothed.
I have both a newly rebuilt lift pump plus an electric lift pump / filter at the tank.
Overflow spring in IP is new (slightly stiffer spring)
I do not have a cigar hose, but I have tried without any hose at all and no change.
As mentioned, once the engine get some heat into to it runs fine! I have done plenty of searching but haven't run across this issue before

Sounds like incomplete fuel burn in one cylinder when engine is not at operating temperature,
and/or possibly worn springs/sticking flyweights on the governor.

Some possible causes of incomplete fuel burn/surging at idle: poor quality fuel, low compression, valves tight, poor injector spray pattern
- pop pressure imbalance between injectors, air incursion, poor condition of glowplugs, or idle set too low.

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78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

I know the superturbodiesel forum is pretty much dead now but those guys would have a lot more experience when it comes to superpump problems.

who built your pump? did u just buy the elements and take it to a injection shop or did u get from benzforce or dieselmaken.

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This won't cost anything or take much time. While the Engine is running cold and loping. Go to the wire terminal block in front of the batter on the fender well.
You are going to find a white wire (which goes down to the starter solenoid and you don't want any positive voltage going to that while the engine is running) and under it a purple wire.

The purple wire goes to the glow plug relay and turns the glow plug relay on during cranking.

Unscrew the the screw that holds down the white and purple wire and keep the white one out of the way and touch the purple wire to either of the other 2 terminal screws and it will activate the Glow Plugs. If it is a fuel burning issue the heat from the glow plugs will smooth out the engines idle.

When done shut the Engine off and put the wires back where they were.

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84 300D, 82 Volvo 244Gl Diesel

Check out my videos and see if they help. I have same pump. Drip timing them is very finicky and it takes people. The sweet spot is 2 millimeters between correct drip, no drip and full flow! Loosen pump, wrap a dishrag around it and use a visegrip to move it back and forth. The second guy, pump the fuel and tighten pump when you hit the correct spot.

https://youtu.be/oj3kYgKzLE8

https://youtu.be/5BCAPMkdZbQ

https://youtu.be/vemjU8Zt000

Note, on my engine I found that the default timing was retarded. I'm running at 26btdc in the final video and you can see for yourself how it runs. Also, I didn't touch any adjustment on the pump itself. Also. My engine has a brand new timing chain and guides. If yours is worn or stretched there will be differences.