Author Topic: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!  (Read 8036 times)

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MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« on: March 29, 2004, 08:21:18 »


(The continuing story of “My car won’t run when its warmed up”)

I bought my 67 250 SL from a friend who had spent considerable time and money trying to get it to run.

I figured sooner or later, some small anomaly would show up and prove to be the cause. When I bought the car, my friend had paid $3000 to have a full “tune up” done which included the usual items, to no avail then a checking of the fuel tank and a freshly remanufactured fuel distributor/pump from Pacific Fuel injection.,….none of it worked……..the car would drive for about 15 minutes then begin running progressively worse and shortly would die and not restart until it completely cools off.

A shot of starting fluid in the intake and it would start and run for a few seconds,……….so,…..it was definitely a fuel issue.

So,…………..I read the tech article and decided to drain the fuel tank and check the strainer,………seemed OK,………..it didn’t look like a big deal so I went ahead and dropped the fuel tank then confirmed that all the fuel return lines into the tank and forward were clear………..they were,I could blow compressed air through them.

So, since the car had already been converted to an aftermarket fuel pump with an integral filter,………I went ahead and replaced it and all the related fuel hoses at the back of the car…..just figured I was already down there and it was cheap insurance.

Net result,…………….No Change!

I then Read through the article on how to adjust the throttle and injection pump rods so that the fuel injection arm and the throttle arm both hit their full stop positons at the same time.

Turned out that the throttle stop had been adjusted previously,…..so that it was open instead of at the “Sticks Slightly” position,….so I corrected that by lengthening the throttle rod about ¼” and checked for proper synchronization……….spot on.

I was hoping that would turn out to be the problem,………….AND, the car did start easier and run better than before…………….BUT

AFTER A FULL WARM UP AT IDLE AND TWEEKING THE IDLE AIR SCREW FOR THE BEST IDLE ,…..JUST WHEN I THOUGHT I HAD IT FIXED, I DROPPED THE HOOD, JUMPED IN, BLIPPED THE THROTTLE IN PREPARATION OF DRIVING OFF,……..IT DIED,…. IT RESTARTED, BUT DIED IMMEDIATELY AND WOULD NOT RESTART.

Following the suggestions in the technical article, I turned the brass idle fuel mixture clockwise first 2 then 4 clicks clockwise to enrichen the mixture,........but no change,...I returned The idle fuel to the original position and even tried counterclockwise (leaner) two clicks..............no good,...still would not start.

Just to check things, I let it cool down for 4 hours this afternoon after I made the latest adjustments. As usual, it fired up fairly quickly and I drove it for about 15 minutes then it started to start running poorly so I hot footed it back to the house.

I CLEARLY STILL HAVE A FUEL STARVATION PROBLEM ONCE THE CAR REACHES FULL OPERATING TEMP.

I NEED HELP ON WHAT TO DO NEXT. Any suggestions?

THANKS IN ADVANCE,
BRIAN COLLINS

Brian

rwmastel

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Re: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« Reply #1 on: March 29, 2004, 10:58:45 »
Brian,

Search the tech archives and discussion forum for info relating to the warm up valve on the injection pump.  I've never worked with mine, so I don't know the intricate details of it.  I know it adjusts the amount of air passing in through the air filter on the FI pump that gets routed to the intake manifold, thereby changing your fuel/air ratio.  This is one physical thing that changes at warm up.  Your valve could be stuck, worn, or not adjusted.  There are ways to test and adjust it.

Rodd
Powell, Ohio, USA
1966 230SL, Euro, Auto, Leather, both  tops
1994 E420
Rodd

Did you search the forum before asking?
2017 C43 AMG
2006 Wrangler Rubicon
1966 230SL auto "Italian"

ja17

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Re: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« Reply #2 on: March 29, 2004, 13:55:46 »
Hello,
If you have a pressure guage you may first want to take a fuel pressure reading and volume reading especially when the car is acting up this will tell you if something is plugged. You will have all kind of mysterious problems if you do not have correct fuel pressure and volume. I am highly suspicious of your Auto Zone fuel pump.
Often times a contaminated fuel system will run ok at first. As the dirt and rust is stired-up , particles begin to build up on the screens in the electric fuel pump and tank screen from pressure. When enough debris collects and the fuel flow is restricted the engine fails. After resting for a while the crud falls away from the screen until the fuel pump turns on again then the cylcle starts over.

Check the fuel delivery and return system, if you have not yet. If you have something plugged it will prohibut fuel from getting to the injection pump. It may not happen all at once. The screen in the tank is the first line of defense. Next the screen in the electric fuel pump intake fitting, should be checked, next the fuel filter should be changed. While the filter is out look in the filter canister for dirt and rust, this may be a clue. Lastly make sure the return fuel line is clear. Take the fuel cap off and blow compressed air through the line from the engine. Be sure to take the gas cap off when you do this step.
Early W113 cars had vented gas caps. Make sure you have the right cap. Try loosening the cap when the engine begins to faulter.

Keep us informed and we will go to the next step! Good luck!




Joe Alexander
Blacklick, Ohio
« Last Edit: March 29, 2004, 16:35:27 by ja17 »
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

ja17

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Re: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« Reply #3 on: March 29, 2004, 14:04:33 »
Hello again,
Also "read your sparkplugs!" Remove some immediately after the problem. They may show you what is going on! Collecting all the data will guide you to a correct diagnosis.

Joe Alexander
Blacklick, Ohio
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

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Re: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« Reply #4 on: April 06, 2004, 15:02:42 »
Brian:

I just replaced my fuel pump with a MB w113 specfic pump.  I had the right volume from brand X but not enough pressure to push the fuel through the system.  Therefore I think I was getting a form of vapor lock.  Still dialing everything in fuel/air mixture etc... but the car has not stalled at higher operating temps; yet. I'll keep you posted on how things continue to go.  

How are you coming on your end, diagnosised the problem yet?

Scott

Scott
1966, Signal Red, 230SL
« Last Edit: April 06, 2004, 15:03:06 by n/a »

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Re: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« Reply #5 on: April 06, 2004, 18:08:42 »
Scott, just now seeing your reply....I have continued to try various things as they are suggested but still no success.  How about you??

Brian

quote:
Originally posted by Pagodadriver

Brian:

I just replaced my fuel pump with a MB w113 specfic pump.  I had the right volume from brand X but not enough pressure to push the fuel through the system.  Therefore I think I was getting a form of vapor lock.  Still dialing everything in fuel/air mixture etc... but the car has not stalled at higher operating temps; yet. I'll keep you posted on how things continue to go.  

How are you coming on your end, diagnosised the problem yet?

Scott

Scott
1966, Signal Red, 230SL



Brian

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Re: MY CAR WONT RUN WHEN FULLY WARMED UP---NEED HELP!!
« Reply #6 on: April 07, 2004, 16:48:36 »
I had a very similiar problem.  An auto shop gave me carbon filament wires.  When I put in the proper copper core wires everything worked fine.

Rupert