Surging stop lever---a sign of a fuel pump going south? - PeachParts Mercedes-Benz Forum

bob_98sr5 · #1 10-05-2007, 11:59 AM

Hi guys,

Since my last post many weeks ago, I've not done much with the 87 300DT except rust treatment. for those of you who are interested in reading about it, see my blog at www.biodieselbob.blogspot.com.

Since my time has been spent on rust repair, its sat in the garage for 2 weeks, so I decided to take it for a spin. And yes, its quite fun and scary at the same time to see a gigantic hole in your floorpan and watch the road underneath you

. Anyways, I noticed that there was a surging sound coming from the engine. So I opened the hood and i can see the stop lever moving up and down. Not that much, but it matched the sound of the surging sound, so I am confident it is related.

My guess is that it has something to do with fuel delivery. Is this the sound of a dying fuel pump? Are there other things that I should check? I saw a tech article about replacing the o-ring, but i'm guessing that this might not be it---or I maybe wrong.

Any advice would be greatly appreciated.

Thanks,
Bob

winmutt · #2 10-05-2007, 02:26 PM

Just for SnG did you pull the shutoff vacuum line from the IP?

bustedbenz · #3 10-05-2007, 02:29 PM

I'm interested in the answer to this as well. mine hasn't gotten bad enough to surge the engine yet but it moves of its own accord quite a bit now.

bob_98sr5 · #4 10-05-2007, 02:41 PM

winmutt,

No, I did not. If I did and it still moved, what would this indicate? Sorry, my engine knowledge at this point is still on the newbie side. But ask me about a 3.4L Toyota V6 and I'll answer it

Bob

2.5Turbo · #5 10-05-2007, 07:24 PM

It would indicate that the vacuum valve in the key switch was leaking vacuum when it's supposed to be closed. When that valve opens (when you shut the engine off), vacuum is applied to the shutoff valve which pulls on the stop lever linkage, shutting off the fuel delivery in the IP.

The car shuts off immediately when you turn the key, right? If so, your shutoff valve is OK and you should be looking at the key switch.

Cervan · #6 10-05-2007, 07:32 PM

Your lift pump is completely devoid of anything to do with the IP other than being on the same cam.

winmutt · #7 10-05-2007, 07:50 PM

Quote:

Originally Posted by bob_98sr5

winmutt,

No, I did not. If I did and it still moved, what would this indicate? Sorry, my engine knowledge at this point is still on the newbie side. But ask me about a 3.4L Toyota V6 and I'll answer it

Bob

As stated does the car shut off with the key? With the lever?

Cervan · #8 10-05-2007, 07:51 PM

Quote:

Originally Posted by winmutt

As stated does the car shut off with the key? With the lever?

Now that i think about it, that would indicate that one of your govner springs are either, broken or loose.

bob_98sr5 · #9 10-05-2007, 10:20 PM

yes, the engine shuts down with the key and by depressing the stop lever downwards.

cervan: govner spring...where is this spring located?

while my stop lever is not leaking like this one: http://www.peachparts.com/Wikka/OM601InjPumpOilLeak

i'm going to clean the stop lever because it does look a little oily and replace the rubber o-ring (if I do have one in my parts drawer)

Cervan · #10 10-05-2007, 10:45 PM

it requires the pump to be taken off and repaired on a bench.

1987300sdl · #11 10-05-2007, 10:53 PM

bob_98sr5,
My 87 sdl (6clynder) has a similar problem. It does not surge, but I can rev up the engine to about 3g, and the lever will drop down, and restrict the fuel. It has never died, but talmost.
When I drive it, it hits about 3500, and does the same thing. I let up on the throttle, and it brings it back to live.
The engine shuts of imediately with the key or the lever. I have checked for vacuum leaks, but acnt find any. All my door locks work ok, it shifts fine (Until it hits 3500rpm), and all my controls inside work just fine.
Do you have any ideas?

bob_98sr5 · #12 10-06-2007, 01:50 AM

1987,

i had the same problem too. i adjusted the idle control knob upwards to 6 or 7. i dont have that stalling problem anymore.

cervan,

excuse my ignorance, but which pump? fuel? IP? and govner...i searched for that word, but nothing came up. are you spelling it correctly or am I missing it?

thanks,
Bob

Cervan · #13 10-06-2007, 03:24 AM

Is this injection pump Electronically controlled or mechanically controled? It matters alot. If its electronically controlled its either a solinoid or computer problem. If its mechanical. the Injection pump as a whole. must be taken off and disassembled to get to the Internal governor weights and springs.

bob_98sr5 · #14 12-16-2008, 03:34 AM

Over a year later, I'd like to update that i had some pretty leaky fuel issues going on. I changed the hoses, fuel filters, and tank screen. but the one thing that made the biggest difference was changing out the IP delivery valves. not only did it fixed the stop lever surging, but also made this thing fast again.