1969 300SEL won't pass emissions.

The Carbon monoxide was way too high, so I took it to an import specialist and he's saying that I need a new fuel injector pump. It's not the fuel pump, but the injector pump. The mechanic said that these are not very adjustable and I need a new one - which he said costs around $1600. Yikes! Does anyone know any tricks to adjust these so I don't have to buy a new one? Or maybe the problem with the emissions is somewhere else? Also, I've searched for a couple of hours online trying to find one, but haven't been successful. I find lots of fuel pumps, but no fuel injector pumps. Does anyone know if this part has another name, or a part number that would make it easier to find? Thanks for any help. Brandon

Need to know which engine?

Brandon, does your 300SEL have the 6.3 V8 or the 2.8 inline 6?

2.8 inline 6 cylinder

Advanced tuning of the 2.8 liter.

Hi Brandon, there are ways to adjust the mixture on the injection pump that can help unless your engine OR pump is worn out. The fuel injection adjustment procedures are a little complicated to try to cover in a short post.

But before you start spending money you need to determine the mechanical health of your engine. Do a valve adjustment (during which time you can inspect the condition of your camshaft). After that - do a compression test. If your compression is low no amount of adjusting will fix your emissions problems! Once you are certain your engine is internally healthy you can proceed with the following:

If the car has been sitting for a long time you first need to lubricate inside of the pump. Start by getting your fuel tank almost empty. Add some Marvel Mystery oil or auto trans fluid to the gas tank - about 1/4 quart to 2 gallons of gas. The engine is going to smoke so don't drive it out on the road! Run it for 30 minutes with the oil mixture... Next put 5 gallons of fresh fuel in your tank and one full can of Chevron Fuel injector cleaner and drive the car.

Next thing to tackle is the ignition. You must have a very hot spark to get the fuel to burn properly. The old point ignition is lacking and it must have no shaft play and be super tuned for your engine to burn clean. I would recommend you install an electronic ignition system for super hot spark resulting in better performance. I have done this on numerous 113, 111 and 108 chassis cars with great success. We sell the electronic ignition with complete instructions. CLICK HERE to read more.

If you do the above with no improvement then you can tackle the injection pump. Try to find a Mercedes specialist who has worked on these engines before. Might have to be an "oldtimer." He might be able to adjust it enough to pass emissions. If he determines the pump is bad you can send it our for overhaul (cost is $800 to $1000). I may have a good used injection pump here if and when you determine it is the culprit.

Let us know what you discover. It may be helpful to our other readers.

Kent Bergsma

turns out that pump is not the problem

Kent, Thanks a million for the advice. I called my mechanic today and he said that during the couse of doind a valve adjustment he found a couple of leaking vacuum lines which he fixed. He said the the pump started to respond correctly at that point, so it sounds like the pump was not the real problem. It passes emissions at high speeds now, but he said that the idle needs to be adjusted a little to pass at low speed, which he said isn't a problem. I asked him about the Crane ignition system and he said it would help a little, but not much. Since he already tuned up the existing ignition system, I think I'll just drive it for a while, then consider the Crane upgrade. He seemed to think that it wouldn't help all that much, though. Kent, in your opinion are the improvements quite significant with the Crane, or is it just a little improvement? Over the long run, anything I can do to improve the performance of the car significantly would be worth it, but small improvements don't make sense right now. Anyway, thanks again for your help. I'm chomping at the bit to get this beauty out on the road! Brandon

Electronic ignition

Brandon, the improvements you ask about are subject to a number of things. They will vary depending on the condition of the following:

Engine compression
Camshaft timing (chain stretch)
Quality of fuel injectors
Injection pump timing
Condition of distributor shaft bushings
Spark plugs and plug wiring harness
Internal condition of injection pump

So in essence I can not say what your improvements might be. The advantages of the electronic ignition are spelled out in the item description. Keep in mind there are other advantages not just related to fuel burn. What about never having to adjust or clean your points again? And if you leave your car sitting for a long time there are no points to corrode!

In the end you have to weigh opinion against fact and make the decision yourself. Find others who have made the conversion and ask for their input. I have had customers come back and swear they have a new car after converting.

1969 300SEL won't pass emissions.

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