Engine stops on longer trips

[savardrobertf]

1970 280SL  Engine starts fine and runs OK on short trips 10 minutes or less.  On longer trips the engine begins to run rough, particularly from a dead stop.  Eventually the engine cuts out and may or may not restart until it has completely cooled down.

[waqas]

Check your fuel feed and return lines (they run the length of the car).

There's lots of information (especially regarding debugging fuel-related problems) on the forums if you use the 'search' link in the top-right corner of this page.

[69280sl]

You didn't mention temperature or overheating. Overheating which is common on 280's could cause your symptoms. Is your temperature guage functioning? Accurate?

Gus
68 280sl, signal red/beige

[J. Huber]

Also, I am curious how long has this been happening? In particular, is the car new to you? -- or have you had it longer and it just started doing this? Does it happen when the tank is low or full?Either way, what kind of maintenance has been done recently? Points, plugs, fuel filters, etc... This might help narrow things for you.

[ja17]

Hello,

If the engine has fuel, air, compression and spark on time it will run.

Air is a given, compression is not an issue since the car eventually re-starts.  Test for spark by holding the coil wire (distributor end) close to engine ground. Have someone crank the engine. You should see the spark. If you have spark fuel is the issue. Make sure the main fuel filter is clean. Do a fuel volume and pressure check.  Keep us up to date.

[savardrobertf]

Water pump replaced last Fall...guage seems to be functioning as no evidence of overheating.
Thanks!

quote:Originally posted by 69280sl

You didn't mention temperature or overheating. Overheating which is common on 280's could cause your symptoms. Is your temperature guage functioning? Accurate?

Gus
68 280sl, signal red/beige

[Longtooth]

could be fuel tank debris problem with clogging "flower pot" screen... your symptom (runs fine for 10 minutes, then dies, and restarts after waiting 'til car cools down) could be mistaken for the time it takes for fuel to leak thru the clogging "flow pot" screen.  

I say this because of direct experience.... I drove away from the shop with a new engine that had been ideling for at least 20 minutes before i drove off.  I drove down the free-way for 10 minutes and car sputtered and died.  I pulled (coasted) off to an exit and parked... looked under the hood, under the car, and tried to restart... it started up fine then coughed and died within a minute.  I waited (hemmed and hawwed, ****ed and moaned) for about 15-20 minutes and tried to start again and it started up fine and ideld fine.... so I drove off toward a gas station I knew was about 3 miles down the road... but just before I got there the car sputtered and died again.  Problem was that my gas tank was rusty and I hadn't had the fuel tank replaced.... towed car back to the shop had tank looked into ---- the screen around the fule intake was clogged bigtime... so that time I waited was the time it took for fuel to seep thru the clogged screen.... car would run fine for a while, then get starved of fuel.  Replacing the tank with a new one fixed that problem forever.

[hands_aus]

have you checked the return fuel line to the tank? Is it free flowing?

[glennard]

It's the old 'Clogged Shroud of Fuelin, there will be no a-Tourin.'  If rust and crud blocks the make-up into the quart sized shroud in the center of the tank, the engine(electric fuel pump) is starved(when the gas level is below the top of the shroud).   Fill the tank full and the gas flows over the top of the shroud.  When the tank level falls about 4 or so gallons, then the starvation sets in.  I've taken many pounds of rust and crud out of tanks.  Best way to fix is to remove level sensor, drain tank, turn car upside down, shake(don't stir) debris out, right car, replace sensor.  Actually, being very careful of gasoline hazards, etc., the tank can be drained and the crud vacuumed out.  Clean/replace all gas filters and screens in the lines. Keep safety in mind!

[J. Huber]

Speaking of fuel filters, I just received one to have for my next change. It looks a little different than the last one I used (I think). It is basically white cloth. Does this sound right to you guys? Part number hand-written on the MB box is 000-477-6415 (which matches the last one I used). The printed number on the box, however, is a different one.

[Naj ✝︎]

quote:Originally posted by J. Huber

Speaking of fuel filters, I just received one to have for my next change. It looks a little different than the last one I used (I think). It is basically white cloth. Does this sound right to you guys? Part number hand-written on the MB box is 000-477-6415 (which matches the last one I used). The printed number on the box, however, is a different one.

James,

The cloth one is a diesel filter as MB used the same filter housing on diesel engines.

Personally, I like them better. I was told it is a finer filter than the paper element.

naj

[J. Huber]

Thanks Naj. Glad to know I wasn't imagining the difference... And I take this to mean its perfectly ok to use on my car?

[Naj ✝︎]

quote:Originally posted by J. Huber

Thanks Naj. Glad to know I wasn't imagining the difference... And I take this to mean its perfectly ok to use on my car?

I use them on mine...

naj

[hill]

Try loosening or removing your gas cap. If your tank is half full or less. Then let us know what happens.

[J. Huber]

quote:Originally posted by naj

quote:Originally posted by J. Huber

Thanks Naj. Glad to know I wasn't imagining the difference... And I take this to mean its perfectly ok to use on my car?

I use them on mine...

naj

That's all I wanted to hear!

[savardrobertf]

Points and plugs were cleaned, although recently changed they were loaded with grease.  Also the fuel/air mixture was adjusted.  Car is running the best since I acquired it last summer.  Thanks for your response.

quote:Originally posted by Longtooth

could be fuel tank debris problem with clogging "flower pot" screen... your symptom (runs fine for 10 minutes, then dies, and restarts after waiting 'til car cools down) could be mistaken for the time it takes for fuel to leak thru the clogging "flow pot" screen.  

I say this because of direct experience.... I drove away from the shop with a new engine that had been ideling for at least 20 minutes before i drove off.  I drove down the free-way for 10 minutes and car sputtered and died.  I pulled (coasted) off to an exit and parked... looked under the hood, under the car, and tried to restart... it started up fine then coughed and died within a minute.  I waited (hemmed and hawwed, ****ed and moaned) for about 15-20 minutes and tried to start again and it started up fine and ideld fine.... so I drove off toward a gas station I knew was about 3 miles down the road... but just before I got there the car sputtered and died again.  Problem was that my gas tank was rusty and I hadn't had the fuel tank replaced.... towed car back to the shop had tank looked into ---- the screen around the fule intake was clogged bigtime... so that time I waited was the time it took for fuel to seep thru the clogged screen.... car would run fine for a while, then get starved of fuel.  Replacing the tank with a new one fixed that problem forever.