Hard to restart after running for a while 380SL

[Wes Curry via CarKB.com]

Help! I just bought an '82 380SL. Love the car, but.... The car starts very
easily when it is cold( first start of the day) but if I drive it for about
30 minutes or more, then stop the engine for more than a few minutes it
seems to crank over for an exceptionally long time before it fires up once
again. If it sits for several hours it starts up right away. I have no idea
of what could be causing this problem, I would appreciate any advise on
this subject. It idles good when first started, but once driven for a while
and restarted it runs kind of rough when it first starts (after turning
over for an eternity). Thanks Wes

[Benz...@webtv.net]

You need a new fuel accumulator, and fuel filter. Your problem with
hard start when hot,will be solved.

[T.G. Lambach]

The fuel system operates at about 45 psi pressure. It could be that one
or more fuel injectors is leaking into the engine after it's shut down.
That causes a "flooded" condition in the language of old carburated
cars. I just fixed this problem on my car by replacing one injector.

Try this, step lightly on the gas pedal when you crank the hot engine -
it will start much faster if, in fact one or more injectors is leaking.

Fuel injectors can be removed and professionally cleaned and tested, you
don't necessarily need to buy new injectors. Of course you should first
try some fuel system and injector cleaners before tearing into the fuel
system, but if that doesn't fix it the you'll know what to do.

I found the leaking injector by parking the car for a few days and then
removing the spark plugs. In my car #6 plug was wet with fuel because #6
injector was the leaker.

It's fixed and the motor runs and starts perfectly.

[marlinspike]

Could it not also be an engine that's set too rich or perhaps a leaky
fuel injector seal? Also, if the system is not holding pressure, he
should be able to start the car without trouble by leaving the ignition
on without starting the car for about a minute (the pump will build up
pressure..actually maybe not on an 82, not sure). Also, if he knows the
guys at an independant shop they should be able to test that the system
is holding pressure for free.

[Tiger]

TG... this is CIS fuel distributor type... not like your individual fuel
injectors.

The most likely culprit would be the fuel accumulator. On one side, there is
a rubber hose, disconnect that and if you see fuel flows out of the
accumulator, then it is bad.

Other possibility is the pressure compensator on top of the fuel
distributor... you can buy a kit cheaply and replace it.

[Wes Curry via CarKB.com]

Yeah, the first thing that I thought was that the engine was running too
rich. I just got the car from Colorado Springs, Co. and I had it brought to
Fort Worth,Tx and that caused me to think that it may be running too rich.
But I appreciate the advice. I will try to check the accumulator, like
suggested. I will also run some injector cleaner thru the tank. I will try
pressing ligtly on the accelerator when cranking. Maybe with all of this
good advice that I have recieved something will fix my problem. Again many
thanks..... Wes

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[Wes Curry via CarKB.com]

Is the fuel accumulator located under the car near the fuel tank? I've
really got to get some sort of repair and maintenance manual for this auto.
Thanks for your advice. Wes

[M. Davis]

Yes, get the repair manual on this 23 year old money pit. E-bay has
them and they have the diagnostic routines for fuel system problems.

Your beast is hard starting when hot because all the fuel in the
injector lines vaporizes and you have to blow it out with the starter
until you get liquid fuel and it starts. The purpose of the fuel
accumulator is to keep pressure in the system when hot and prevent this
vapor lock.

The accumulator is the most common problem, but other possible pressure
leaks are: injectors, pressure regulator (in the fuel distributor),
cold start valve, fuel pump check valve, and, iirc, the warm-up
compensator, and a couple of other places. Diagnose before you replace
- you will run out of money before they run out of parts. Often a bad
accumulator will howl at you.

The fuel accumulator is the top one of three cans held in a single
bracket near the right rear axle, behind a black plastic cover. Pull
the cover first. The bottom can is the fuel pump, the middle one is
the fuel filter.

The pressure side of the accumulator has a steel high-pressure fuel
line into it. If the diaphram has a hole, fuel will leak through it
and out the rubber relief line on the other end of the accumulator back
into the intake for the pump through a pressure damper. If you clamp
this line shut (hard, it is really stiff rubber, you may damage it and
have to replace anyway) and the problem goes away, it's the
accumulator. Make sure you get the plastic sleeve between the pump and
the bracket when you reassemble. With a car this old, be looking to
replace all rubber fuel and vacuum lines before they fail completely.
If you don't , leaks can cause all kinds of hard-to-diagnose problems.
Do fuel system repairs outside with a fire extinguisher handy.

Mike

'82 380 SL - 163K
'81 380 SL - 124K
some people never learn

[marlinspike]

380 a money pit? The only non-maintenance items my 380SE has needed in
the past 19.5 years has been fuel injectors/seals and a fuel
distributor. Granted, I choose to live with a non-working A/C, but I'd
say these are anything but money pits.

[Tiger]

Yep... I agree... simply by saying moneypit can be applied to any cars you
buy and have no idea how take care of it... only your mechanic who can rip
you off...

[Jim B.]

Sounds to me like good 'ole fashioned VAPOR LOCK. Frustrating problem because sure, it's easy to diagnose, and even though it's a hassle it's easy to deal with right there and then it's hard to coax it to go away for good.
Go to your parts place and bite the bullet on a can of starting fluid (I like the brands that give the straw - better aim. Get the engine warm like you describe, & when it vapor locks, pop the air filter/carb cover off and top and have someone turn the key. A couple of 2- second squirts & it'll start, but then what? Well, there are lots of ways to minimize it but maaaaan, ya can't beat a $3 can of starting fluid.

https://help.summitracing.com/app/answers/detail/a_id/5242/~/what-is-vapor-lock%3F#:~:text=The%20first%20step%20in%20preventing,the%20fuel%20in%20the%20lines.

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