Hello,
I have an 84 300TD which I replaced the injection pump because the old one was leaking and causing a lot of smoke. I purchased what I was told was a good pump and it looks good with no leaks and all the factory markings are good. I installed it and started the car but the engine started running away after it caught. I tried the stop function under the hood and that didn't work but I pulled the fuel line and in about 15 seconds the engine stalled.

The only thing changed was the injection pump and looking at the stops and idle screws they all appear to be closely set to the old pump. What would cause the replacement pump to go full throttle? I checked the shut off valve before installing and it held vacuum and did not appear to have been messed with.

Thoughts?

If the vacuum shut off valve at the rear of your new injection pump had been
replaced and was installed incorrectly--that could have caused your runaway engine.
Read this tutorial at Diesel Giant about the shut off valve and how to
correctly install it. https://www.dieselgiant.com/repairyourshutoffvalve.htm

Good thing your were able to pull off the fuel line quickly.



Jeff

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end

Run away in shop, after correct placement of vac. shut off, engine was started with
noise and very poor running, valve adjustment was done, all the adjustment nuts had
come loose, another few seconds and good by engine, you might want to check!

I am assuming this is an MW fuel injection pump with the rack damper/governor idle pin on it. I have read that if that is turned too far in it will cause a run-away.

Other possibles. The linkages were not hooked up correctly. Pop the linkage off of the throttle arm. You won't be able to use the manual shut off like that but the next time you need to set up to block the air going into the engine.

You have 5 elements. On many fuel injection pumps if one element gets stuck it holds the rest in that position. If that position is the full fuel position it the engine runs away.

Do some reading. If you remove the vacuum shutoff when it is off, you can get at the rack. You want to see if the rack moves easily back and forward without sticking.

While sellers do like it is also possible that the pump was working, and it sat long enough for the fuel to dry up in it and because that mentioned sticking rack.

Is there any evidence that someone removed the rear cover of the governor? People over on the super Tubo diesel forum like to remove the cover and change adjustments inside of it.

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84 300D, 82 Volvo 244Gl Diesel

What was leaking and what color of smoke was there and did the smoke smell like fuel or oil?

I am asking because in my experience with inline fuel injection pumps with mechanical governors if no one has touched the settings when they get worn out, they don't produce excessive fuel.

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84 300D, 82 Volvo 244Gl Diesel

The previous owner did a lot of monkeying with the pump. The wagon is the fastest wagon I have driven when cool but when it is up to temp it rolls coal and stumbles. All of the "don't" touch factory markings have tool marks and I'm certain they were not BOSH certified. That is why I chose the used pump... alas I think I might just have to bite the bullet and get a rebuild

The pump was not opened, I just broke the top seal to check the vacuum shut off and as you mentioned the rack is actually frozen and does not readily move. Looks like it may have been good but at this point it doesn't slide at all. Frustrating as pulling these is a pain.

If your description is correct that means at least one of the element plungers and barrels is stuck.

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84 300D, 82 Volvo 244Gl Diesel