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Hi Folks,I am doing this to help out my neighbor who has a 1973 merc 450SL.This car has only 77000 kilos on it and has been very well looked after.Here is the problem.My neighbor knows that I am a mech. and my hobby is building hotrods,street machines and anything I can put headers on!!!!. Rich came over yesterday and told me the car was running fine but when he tried to accel.up a hill it would want to die also that it stalled and would not start,but after letting it sit for a couple of hours it started up and drove home. My suggestion to him was to replace the fuel filter and see if that would improve.He bought a new filter and when he went to start it to move it out of his garage it barely ran.He changed the filter and now the car won't start. We have spark,I primed the fuel system and we have fuel to the injecters. But something is not turning on the injecters to fire fuel. We hear the fuel pump turn on when the key is switched on.Also if you pour fuel down the throttle body and crank it over she firesw up to the fuel runs out. Oh yes it has efi not the bocsh setup.Can you give us some insight on this? Thanks and what a great site
 

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2001 SLK320, 2001 C320
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There are 2 sets of points in the distributor. One set controls spark (as you would expect). The other set controls fuel injection. (Eek! Madness!) Be very nice to those points as new replacements don't exist, but they are likely your culprit.

For more information, do a google search on Bosch D-Jet....
 

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500SLC #2624. Black on Black.
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Hi Folks,I am doing this to help out my neighbor who has a 1973 merc 450SL.This car has only 77000 kilos on it and has been very well looked after.Here is the problem.My neighbor knows that I am a mech. and my hobby is building hotrods,street machines and anything I can put headers on!!!!. Rich came over yesterday and told me the car was running fine but when he tried to accel.up a hill it would want to die also that it stalled and would not start,but after letting it sit for a couple of hours it started up and drove home. My suggestion to him was to replace the fuel filter and see if that would improve.He bought a new filter and when he went to start it to move it out of his garage it barely ran.He changed the filter and now the car won't start. We have spark,I primed the fuel system and we have fuel to the injecters. But something is not turning on the injecters to fire fuel. We hear the fuel pump turn on when the key is switched on.Also if you pour fuel down the throttle body and crank it over she firesw up to the fuel runs out. Oh yes it has efi not the bocsh setup.Can you give us some insight on this? Thanks and what a great site
Hey Stage2,

Firstly, the EFi is still a Bosch setup, it is Bosch D-Jet, as opposed to the later Bosch K-Jet.

Have you looked at the trigger points in the distributor? That could well be a problem.

Hopefully it is not your neighbour's EFi module that is gone, as that may also cause the problem.

Oh, by the way, welcome to the forum. I'm sure other will be able to either offer more info, or correct mine if it is erroneous.

Foto.
 

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Discussion Starter #5
Hey Guys! Thanks for the quick replies,Does anyone have the specs that the trigger points are set at? And how does one go about getting replacements if they are no longer available? Looks like with all this great info I will be seeing a lot more of my neighbor. This is what I have for toys that I have built and sorry to say not one is a merc. 1988 Mazda RX7 powered by a 5.0efi mustang.1984 mercury capri with a built 351 windsor, 2002 Ford F150 E/C Stage 2 ROUSH with vortech blower. Hope I didn't bore you guys and many thanks again
 

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1998 SL500, 1959 220S, 1970 280SL
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When cranking the engine, open the throttle a bit, and put a stethescope probe (or use a piece of hose) on an injector. If it clicks, then check the fuel pressure (2 bar). If it doesn't click, go the trigger point/ECU/wiring route.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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The early 450SLs had a different type of connector than the one in the picture - Maybe just check the contacts are clean and that it is properly inserted.

I had a similar no-start problem once. What it turned out to be, was that the thin green wire from the distributor to the terminal near the coil had fallen down onto the exhaust shield, which had melted the insulation and the wire was shorting out. At first it was intermittent, but once I stopped at a gas station on our 401 highway and the car would not run at all when I went to start it. It was then that in desperation I found the problem.

Might be worth while checking it as well as the other connections at the resistors and the coil itself.

Assume regular points are set properly - I forget number - about a business card thickness will work.

But, if it is a fuel problem,

The trigger points seldom fail, but do sometimes need cleaning. Easy to check, but if you remove it, make sure the distributor position is carefully marked before removal - (don't ask how I know that!). Actually, you can check trigger points without removing distributor by using an ohmmeter. Connect meter to 12 (common) and 21,22,13, 14 alternately while rotating engine - resistance should vary from 0 to infinity as points open and close.

Another thing to check might be the pressure sensor which is the heart of the system. First make sure vacuum connection from manifold is sound. Then check resistance between terminals 7 & 11 and 8 & 11. Should be infinity, If "O" check if ground is in cable or in unit itself. (pressure sensor is located on drivers side of engine bay and connects to manifold with a fairly large heavy duty vacuum hose - maybe 1/2" diam?)

Lets us know if you get it going!
 
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