FI pump rebuilding

[philmas]

I know this subject is anything but new.
Anyway, my question is: what are the symptoms of a worn-out FI pump?
My car has an "hesitating" behaviour when cruising at low speeds , particularly in traffic jams.
This problem never occurs when the engine is cold, probably because the cold start device supplies enough gas to cure what looks like a "starvation" issue.When hot, it could become a nightmare driving in dense traffic.

My mechanic partially cured the symptoms by tuning thr injection system, but the benefit only lasted for one year, and then back again.
He told me the only way was to have the FI pump rebuilt.
What do you think?

[merrill]

Call hans at H&R at 631 589 1600
see what he says

Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

[waqas]

I'm sure the experts can better explain this, but as far as I understand, a worn out fuel-injection pump only enriches the mixture, not the other way around...

Starvation sounds like a fuel delivery problem. Have you made sure your fuel delivery system is fully functional? (Does your fuel pump deliver enough volume from the tank? Are your fuel feed and fuel return lines clear? Have you checked the fuel filters?)

Lots of information on the website; just use the nifty 'search' feature.

WAQAS in Austin, Texas

[hands_aus]

Have you been driving the car very much? Did he replace the points? I am wondering if the points have worn and the timing has changed?

After everything in the fuel supply system (filters, fuel volume and pressure from pump) has been checked the fuel injection pump should be the very last thing to rebuild.

Checking includes the adjustment of the linkages, correct adjustment of the venturi valve, Cold Start valve, Warm Running Device, making sure the injection pump thermostat is working properly, replacing plugs, points, adjust timing, make sure all vacuum lines are sealed.

It is a matter of being methodical in your approach and checking every element of the system.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[philmas]

Thanks a lot for advice.
As far as I know, ignition has been checked recently.
moreover, the engine runs fine when cold and in other condition (at high range).

It looks like the car wants to go and then stops and go until it reaches 2000rpm or so.

No sputter;only the feeling that someone's depressing and then releasing the throttle between 1000 and 2000 rpm.

People at MB told me some adjustments in the FI system require special equipment from Bosch.Have you heard of it?

[hands_aus]

quote:Originally posted by philmas

Thanks a lot for advice.
As far as I know, ignition has been checked recently.
moreover, the engine runs fine when cold and in other condition (at high range).

It looks like the car wants to go and then stops and go until it reaches 2000rpm or so.

No sputter;only the feeling that someone's depressing and then releasing the throttle between 1000 and 2000 rpm.

People at MB told me some adjustments in the FI system require special equipment from Bosch.Have you heard of it?

Hi,
What model car do you have and is it original to France or was it imported from the USA?

eg 230, 250, 280 ? manual auto? power steering?
just basic knowledge.

Can you also tell us the Injection pump model number ?
It will end in 'something like' R11 or R18
There are 2 small plates on the side of the injection pump.

The later USA 280SLs had a 'speed' relay which can cause problems if it is not working properly.

It is aparently true about specialist tools. There are people like H&R and Pacific fuel injection (do a search for those names) who will/can rebuild your pump to be like new. Everything costs.

Look here too http://www.sl113.org/data/show_table.asp?table_name=usr_parts_and_service_suppliers

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[philmas]

I found this post to be very similar to my concern.
 

quote:Could somebody help me out, where to start solving the problem of my shaking 250SL 1967. When not driving, the engine runs smooth with a
happy sound, without any hesitation going up in RPM's when hitting the accelerator. When driving, all occurs to be the same: a good sound, a happy engine and going up fast and joyfull. The problem starts, the moment I want to drive steady at low speed. The car starts shaking me as if it tells me: "lets accelerate man!! go!!" and after a short while I can't hold it anymore and have no other option as to accelerate or to stop. To complete this story: a mechanic told me that the injection-pump was set to idle, but he did not dare to touch the pump: it's sealed. As last: the Mercedes dealer had no clue; they just checked the Co2 and that was over 8. "to rich" they whispered, but they did not dare to touch the pump either. What now ?

Download Attachment:  250SL .jpg
16.28 KB

The actual word is "shaking" (you just can't imagine how tough it can be sometimes just finding the exact term in a foreign language!)

It seems that this problem did not receive a solution.

My car is a '71 280sl Euro, 4 speed manual.
The FI pump is the late style, w/no solenoid attached at the back.
I don't see a "speed relay" : where would it be located?
My feeling is that my mechanic never found what the issue really was, and his "ajustments" only made some compensation without solving the problem, which lead to the present situation...

[Benz Dr.]

I do over a dozen basic tests to determine if the IP is working properly. Even after I decide to pull the pump I still turn the engine over to 20 degrees ATDC in the small chance that the pump wasn't timed properly to the engine. I've found a few that were not set right.

Aside from a few external adjustments there isn't much you can do with a worn out pump. All engine rebuilds leave here with a rebuilt or at least a re-calibrated IP.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[glennard]

You're not trying to accelerate at 800 rpm going 10 mph in 4th gear up hill, are you?

[philmas]

No,unfortunately, I live in Europe, where cars are most of the time not powered by 7liter-V8 automatic engines and I know these oldies(but goodies)have a limited smootheness at very low rpm.

But there are recent developments about all this.My mechanic finally got his hands in the hardware, and found the engine was running too lean.
And miraculously, everything seems to have gone back into place, and it's running much better now.
Btw, the little "popping" when decelerating have also disappeared!