General IP question

[yARIC008]

Okay, so I have this IDI, it's not a ford but a mercedes. It's my friends that I'm trying to get running for him. He got it for cheap from on of my dad's friends. Anyways, when we got it all we were told was that the IP went bad. The guy that owned it before got ahold of a new/used working IP but then someone gave him a new card, so he ditched this one. So anyways, trying to make a long story short, we get the car home. Starter doesn't work. We replace it still doesn't work, turned out to be a lose ground strap to the engine. We get the starter working finally...

Before we try to start the engine I changed both fuel filters and filled the new ones with fuel cleaner and fuel and put them back on. So we try to start the car... one of the fuel filters is clear so I can see fuel going into the filter from the lift pump or fuel pump, so that's working. We try to start for a few mins while letting the starter cool in between trys. It tries to start but not quite. There is only a faint white smoke coming out the tail pipe that smells like burned oil...

So next i cracked open an injector line and there indeed fuel going to the injectors as fuel was coming out the line when trying to turn it over.

So I guess my question is.. in what manner can injection pumps fail? Can the pump be getting fuel to the injectors but not getting the pressure high enough for the injectors to pop open? Maybe Mel would have the answer to this...?

Anyone have any idears? My next thing to try is WD-40 in the intake to see if it'll fire off a little from that to see if the engine can run.. if that doesn't work next step is to check compression...

 

[Joe Mc]

Does this engine have glowplugs and are they working?

Is this the original IP or the replacement IP?
If it is the replacement IP, who changed it and did they know how to change it?

 

[yARIC008]

The glow plugs seem to be operational but not 100% positive on this. The controller for them gets really hot and the battery gets drawn down like they're working. We cranked it long enough that I think even if they were out it should have started anyways.

It's the original IP i'm talking about here. I want to make sure this one is really shot and there is nothing I can do to help it before i tackle changing it out for the new one. That's why I'm asking these questions.

 

[Shadetreemechanic]

You rarely see problems from those old bosch Ips. I would check the glow plug circut to confirm you are getting heat. Were you able to use the primer pump without problems? Those tend to go bad and then they suck so much air that they don't start worth a flip. A primer pump is less than @20 bucks and goes bad alot more commonly than the ip.
What model benz is it?

 

[yARIC008]

A primer pump? Is that what sucks fuel from the tank or what? The little clear fuel filter I see that comes from the fuel tank I can see doesn't have air in it and is getting fuel pumped to it...

It's a 1983 300SD.

 

[Shadetreemechanic]

The primer pump is the silver barrel with a white plastic cap that is just to the left of the clear prefilter. If you unscrew the top and pump it up and down it primes the injection pump. If you haven't primed it that will lead to a no start condition as well. Pump on it until you get alot of resistance, it will often buzz slightly when its fully primed. Problem with the pump is that they leak air into the system so even though you see the lift pump pulling fuel through the prefilter, it might also be sucking air in at the primer pump. You can often fix a leaky primer pump by getting an oring that will slip over the plastic top and seal where the pump piston hits the aluminum bore.

 

[Agnem]

If you've got smoke at the tailpipe, it sounds like an ignition problem (fuel not burning-glow plugs)

 

[yARIC008]

The primer pump is the silver barrel with a white plastic cap that is just to the left of the clear prefilter. If you unscrew the top and pump it up and down it primes the injection pump. If you haven't primed it that will lead to a no start condition as well. Pump on it until you get alot of resistance, it will often buzz slightly when its fully primed. Problem with the pump is that they leak air into the system so even though you see the lift pump pulling fuel through the prefilter, it might also be sucking air in at the primer pump. You can often fix a leaky primer pump by getting an oring that will slip over the plastic top and seal where the pump piston hits the aluminum bore.

Ah.. I was wondering what that little thing was.

The smoke thing. There isn't much smoke coming out and the little that is only smells like burned oil. It doesn't smell like unburned diesel to me. When my truck won't start b/c of glow plugs or something you get a rich diesel smell out the back.