All is well that ends well. Great when posters like yourself report the eventual solution.

A combination of many small issues is common on really old cars. I almost expect this to occur. That is why I recommend going over things when one aquires a really old car. Also by doing this you become much more familiar with them so the next time may be easier. I am not a working mechanic so my intuition is weak in comparison.

hmmn. this about the only post that describes my problem. However, I have still yet to find time to investigate. Like the other(s) my problem seemed to have developed after installing brand new injectors. Now all my gp's, im about 99 % sure are fine as I replaced them last fall about the time I did a bunch of major maintenance to my 240 to get it road worthy again after having sat dormant for a couple of years. It seems like this problem developed sometime this past winter. I also thought it was cold related but, it would start fine (with the 5 second stumble) in -5 degree weather (yes, im ashamed that I had to drive my 240 this past winter first winter its been driven in since i have owned it but, when I moved I could only take 1 of my car's and had to sell everything off). So anyways, Im pretty sure mine is due to a leaking line under the fuel tank to the main hardline under the car.. It was leaking some years ago and, i noticed it when I use to periodically start it in the garage each week. Hopefully if my work schedule permitts, il be able to figure out whats going on, its just annoying me and seems to be happening more frequently i.e. if it sits longer than 30 mins it may or may not have a stumble at start up.

luckily I have a garage down here now to tinker on it in great idea thread! was definitely interesting the similarities with the new injectors and such

__________________
1983 Euro 240D 277K
2016 Mazda 6
Coming Soon, 2013 Mercedes E350 Bluetec
Formers:
2012- Mazda 3
2007 Outlander- complete pile
1995 E300 Diesel 208K
2007 VW Passat 2.0T 63K SOLD
2003 Jaguar X-type 3.0 Sport Sold 04/11 w/88K
2009 Lexus RX350 9061 miles. Sold 04/09
2008 Mitsubishi Lancer GTS:Totaled Sept.,09 @ 24,000
2003 Infiniti I35 58K Sold
1984 300 turbo diesel 222K

Just to update, since I said I would... Finally got around to installing a new primer pump. Like I said, the old one had to be "glued" together with some gasket maker to keep it from leaking.

No change just from that, although now I was able to test pumping it before starting, and that definitely took the problem away. So now I can move on to inspecting the lines and such.

I was curious about what holds the pressure in the fuel lines... Is there a specific part that keeps the fuel from draining back or is it just a factor of being a closed loop?

If the latter then I could see how a tiny leak would let just enough air in to let the fuel drain back toward the tank yet not cause an obvious dripping line.

-Rog

The fuel pressure relief valve keeps the fuel in the injection pump, the elements keep it in the hard lines.

__________________

Another update...

After doing some more searching and digging, I decided to rebuild the lift pump. I ended up finding one that looked almost new for only a little more than the cost of a rebuild kit, so I threw that on there, figuring at least I would have a spare to rebuild so I could still drive it.

That made the biggest difference of anything I've done (aside from adjust the ALDA, as it would barely move when I first got it). New glow plugs did nothing, adjusting the valves did nothing, rebuilt injectors did nothing (though I'm sure it needed all those things anyway).

The new lift pump helped with cold starts, but more than that it completely cured a vibration problem that I was sure had to do with the drivetrain, and had planned to dig into at some point. No more waiting for the engine to warm up before it has any kind of power. Really curious. Looking through all the threads I found, it's an often-disregarded component (those things never go bad, it's probably fine), so for anyone with mysterious symptoms it's something you might check out. I did not see any way to test it, but it's easy to swap out, aside from the huge oil mess you'll make. I found rebuild kits for between $15-40, depending on how much you trust off-brands.

So now I'm going to investigate the last little bit of roughness when it first starts. I'm thinking a glow plug mod of some sort. At least one to be able to tell when they're actually on. I'm betting they're off when it's rough...

-Rog

Low supply pressure in the injection pump from any cause will give some effects. The only really proper test is to read the injection pumps pressure present in the pump with a gauge. You want to see about 16 to 19 pounds when you are done.

The common causes of low pressure are tired lift pumps, partially obstructed filters and the relief valve has sagged down in pressure retention with age. If one owns a 616 engine I think this is important especially.

I believe there is a spec for lift pump output per unit time. Or you can measure internal IP pressure. I have a kit in the rental section.

Fuel pressure (injection pump internal fuel pressure) measurement kit Funola ........................... $15/week
Tool Rental Master Member List

__________________
85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked