Author Topic: Fuel issues on hot start  (Read 3962 times)

jackmc

  • Full Member
  • Junior Level
  • *
  • USA, AZ, Tucson, Arizona
  • Posts: 13
Re: Fuel issues on hot start
« Reply #25 on: August 31, 2023, 18:45:43 »
I seem to recall there is some way the Injector Pump accounts for things like heat and elevation. Anyone have any ideas how that works? Some solenoid changes the IP cam to pump more/less? How are these changes detected?

Just a thought. Thanks again for you input!

ja17

  • Full Member
  • Platinum
  • ******
  • USA, OH, Blacklick
  • Posts: 7313
Re: Fuel issues on hot start
« Reply #26 on: September 01, 2023, 04:11:21 »
Very likely that, that after-market fuel pump is the problem.
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

jackmc

  • Full Member
  • Junior Level
  • *
  • USA, AZ, Tucson, Arizona
  • Posts: 13
Re: Fuel issues on hot start
« Reply #27 on: September 02, 2023, 22:29:16 »
Very likely that, that after-market fuel pump is the problem.

Why so? There is now fuel at the IP when the engine is hot, unlike before. I mean, I’ll eventually get the original rebuilt and back in, but I don’t think that’s the issue.

Did you see my question about how the IP adjusts for temperature and elevation? Can you help with that?

Based on the symptoms, it sounds like it’s running way to rich, as opposed to just not having gas or not enough gas.

Thanks in advance!

rwmastel

  • Full Member
  • Platinum
  • ******
  • USA, OH, Canal Winchester
  • Posts: 4413
  • Pagoda SL Group: 20+ years and going strong!
Re: Fuel issues on hot start
« Reply #28 on: September 03, 2023, 02:06:33 »
Based on the symptoms, I’m betting my issue is a supply-side issue rather than return or cold start.

However, I still think that is a red herring. .... That’s why I suspected the back flow valve at the fuel pump sticking closed.

It claims to have the same pressure/flow characteristics as original.

All I can suggest is you actually TEST as many things as you can to gather as many FACTS as you can.  People have a hard time helping when there are guesses and assumptions involved.
Rodd

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

Pawel66

  • Full Member
  • Platinum
  • ******
  • Poland, Mazowieckie, Konstancin-Jeziorna
  • Posts: 5187
Re: Fuel issues on hot start
« Reply #29 on: September 03, 2023, 07:07:53 »

Did you see my question about how the IP adjusts for temperature and elevation? Can you help with that?



To directly answer your question, you have all of it here in the Technical Manual.

Adjustment for temperature: https://www.sl113.org/wiki/Engine/WarmRunningDevice
Adjustment for altitude: https://www.sl113.org/wiki/Engine/AltitudeCompensator

I am not a mechanic, just I do some of the work on the car myself. I think you received a couple of good tips from top experts here to follow and check to confirm/deny certain suppositions and claims.
Pawel

280SL 1970 automatic 180G Silver
W128 220SE
W121 190SL
G-class

ja17

  • Full Member
  • Platinum
  • ******
  • USA, OH, Blacklick
  • Posts: 7313
Re: Fuel issues on hot start
« Reply #30 on: September 04, 2023, 04:31:00 »
Check the specs on the fuel pump. Seems that I took one of these off a pagoda some years back. The specs were not even close to being correct, caused all kinds of running and starting problems. There is a Carter Pump which will work, but that is not the one.
« Last Edit: September 05, 2023, 02:10:44 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