Instead of starting a new post bump your old one up in the future.Or things can become confusing. Everytime you post on a thread it moves upwards on the list. It may take a few bumps to get it current again..

I just read some of your other thread thanks to Mr Hunter. I thought it was a little odd that you purchased a new fuel or lift pump. Aparently you have purchased a new hand primer pump instead. There is a world of differance.

Still attempt the primer pump test and tell us what happens. Then you will be looking and testing the fuel or lift pump next I imagine. Depending on the results of the primer pump test.

Could be the fuel shutoff circuit or device as well but establishing fuel is really available is the first step. Keeping on a systamatic approach fixes things.

Intermittent conditions occassionaly require different approaches. You have a constant fault and they are easy to find in comparison usually.

Thanks for the replies and great ideas! I will go through them in depth here in a minute to make sure I check each suggestion, but I want to share what I just found.
First, I unscrewed the relief valve from the engine side of the IP. I took the whole "bolt" out, then unscrewed the 14mm inner cap and took out the spring and ball bearing. I cleaned them both with carb cleaner and reassembled them. After reinstalling them, I repeatedly pressed the primer pump until I heard a very distinct "scritch, scritch" sound every other time I pressed the pump. I am assuming that was the fuel pressure getting to such a level that it was getting through the relief valve. So, that's working.
So now I'm down to the vacuum shut off thingy. As I was looking at the IP, I noticed what looked like a vacuum receptor that was missing a hose. I looked and looked but could not find a loose hose. I then remembered I had found what looked like a vacuum cap after I degreased the engine shortly after buying the car. I had it on my desk since then, and I've also put 1k miles on the car since then, so I didn't think a whole lot of it. Well, it fits perfectly on the receptor. Below are images. Is this correct?

Attached Thumbnails

     

Thanks! Again, apologies for starting a new post and hogging bandwidth.

Linkage operating smoothly. Nothing sticking.

That isn't the shutoff actuator. The shutoff actuator is the thing on the back of the IP with the brown vacuum line going to it. As a test, pull that line off and see if it will start- the pod requires vacuum to kill the engine.

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1984 300D
Euro spec, 5 speed
217,000 miles

Before you start messing with the fuel shutoff. The primer test proved that fuel is available and the relief valve is working. Next sequentially in checking is the lift or fuel pump.

Crank the engine. Is fuel flowing out the relief valve? If not remove the relief valve from the injection pump and see if fuel is flowing even with no system resistance in place. This resistance being the relief valve.

If no fuel is flowing with both these tests get the ten dollar or so lift pump repair kit from the site sponsers and freshen the fuel pump/ lift pump. You can do this and the instructions to do so are in the archives.

You have to make sure the lift pump is functional or not before getting into the fuel shutoff circuit. I kind of suspect it is not or the functioning is so substandard that for all practical purposes it is dead. .Still to be certain tests must indicate that. Or all becomes confusion.


I preffer gauges for these types of tests but you can get by without in most cases.

Another test that is valid now. It was mentioned earlier on your thread by another member. That with someone cranking the engine and another using the fuel primer that the injection pump should process that fuel.

Compency for you to do this is an issue to me but it should be safely manageable. I would take one of the lines off the injection pump itself in your case. The pump element should squirt fuel upward as soon as you crank the engine. With the fuel primer pump being used at the same time by someone.

I am a little aprehensive about you cranking and cranking the engine to see if fuel will come out the loose fitting at the injector itself. We do not want to add a cooked engine starter to the mix at this time.

Nor do you want to miss diagnose something because of another factor. When loosening the line nut at the injection pump and removing the injector line.. The male part the line nut mounts to is the adjustment for fuel volume and element timing. That is used only by an injection pump repair shop. Do not disturb any fittings around that other than the line nut.

Fuel squirting vertically right away when cranking the engine with the primer pump being used it is the lift/fuel pump. No fuel squirting out it is the injection pump shutdown circuit.

Stay with the program adding no variations as variations could add complexity. We are essentially doing absolute go/no go tests. For example you removed the relief valve and cleaned it before testing.

There is no way to know if it was open before the cleaning as the test was not done and indicated that it was or was not. No harm was done though.

When servicing anything you never want it to come back to life before finding what it is. To turn a constant problem into an intermitent problem can be hell to find later.

I am just trying to convey information in a helpful way as many others are. All our various levels of experience are available to anyone on site. We cannot always be right attempting to help on things we cannot hear and see.

In your issue it is straight forward enough that a resolution is doable. If you are a younger guy the self confidence buildup helps. If middle aged or older.
Many guys never serviced many mechanical systems in their lives. Learning a little more does avoid paid for service. If it is not a little frustrating probably nothing is learnt.

Even in retirement I spend a portion of almost every day repairing something or other. Tomorrow I spend the day attempting to modify an adolecents behaviour. This type of thing I do every Saturday. I do find it very hard work to succeed in. To me in reality it is and continues to be some of the hardest challenges I have ever faced workwise. It does not get much easier with experience.

Repairing electronic and mechanical things of even major complexity pale by comparison.

The scritch is the bypass valve working.

The vacuum connector in the picture does not belong there, that is an atmospheric vent = never cover it.

The shut off is the brown with blue stripe in your picture, disconnect it and try starting.

.

Whunter is most likely the most experienced member on these cars on site. An actual working mechanic as well. His views should be respected.

That stated I just wanted to throw in that if the engine starts with the vacuum line removed do nothing to the injection pump. The fault is the rear portion of the key switch not in the injection pump shutoff device.

This is still a simple situation probably.Still I personally would not like to see it compounded. Most of us do only very limited things to the injection pumps.

They still remain a mechanical marvel of some complexity to me. That they generally last so long in service with their tight tollerances required to function remaining so long alone is amazing to me.

You guys are the best!

After my last post I removed the vacuum hose from the shutoff diaphragm and turned the engine over. Lo and behold, the injector caps (which were still 3/4 loose for testing) each were weeping diesel. I tightened them up and turned the engine over again. No start.
OK, at this point I made the call to apostatize from the forum and do (what you guys have been saying I should never do) and that's spray starting fluid into the air input. I have a friend who I've shared my Benz problems with and he said he used to work at a grain silo and any time they had a D8 Cat that had been sitting for a year or so, they'd shoot some starting fluid in it and it'd start right up. OK, at this point I'm desparate; so in goes two quick shots. As I start to turn the engine over, my first thought is "What have I done?" It doesn't turn over smoothly as before, kind of a "clump......clump....clump,clump" (I figure that it's the starting fluid hitting those hot glow plugs and igniting in the chamber before the right compression point) Anyway, the second time it goes "clump, clump, clumpity,clumptiy vrooom!" Success! Its runs smoothly, but is smoking heavily. I figure part of that is the dozens of failed starts over the past three weeks. Once I let it get up to temperature (about 175), I took it out for a drive. On the drive I filled up the tank (29mpg) while the car was running, and then ran it about 4 miles at high rpms in each gear. When I got back to the house, it shut off just fine. This morning (34 degrees outside) will be the test.
Ok, so now I have a brand new lift pump in the car (that I probably didn't need) as well as a new primer pump (which I bought first) for the old lift pump (that I probably didn't need), but a much, much better understanding of how the fuel supply system works. $175 buck in parts isn't too bad of a price to pay for that knowledge, and I've got a spare fuel pump to boot!

Again, thank you all for the time and attention you gave to my posts and your willingness to share your experience and knowledge. I could not have done it without you!

Congratulations, she lives..On the starting juice, a better choice next time would be WD40, Cats and Jimmys are OK with ether as they are direct injection engines, MBs use pre chambers, not a good idea to use ether in them. Be sure to read up on installing a vacuum shut off switch if thats your next task, doing that wrong can lead to a run away engine, very messy Anyway, happy motoring

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

The difference between the D8 and your engine is the lack of the glowplugs in the CAT. Cat's often have a built in ether spray system where you just push a button on the dash to give it a dose of starting fluid in cold weather.

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

WD40 it is. I will inform my friend. Thanks again! BTW, started right up this morning. Easiest start ever despite it being around 33 degrees outside. I attribute that to the new glow plugs. I just did a straight swap with the old style just removing the ground strap and replacing the resistor wires with the 10ga wires. Seems to have worked great. Now it's on to fixing reverse; doesn't want to pop out of reverse all the time. I can live with it for now, but I'll be back! Have a great weekend!

It's not clear to me exactly what the problem was. Was the key switch not releasing the vacuum on the shut off diaphragm?

__________________
1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Either that or the diaphragm was just stuck. I've turned it off and on a couple of times since then with no problems.
Purchases made during this fit of troubleshooting:
1. Primer pump for old fuel (lifter?) pump. $17 (the old one was leaking anyway).
2. New hoses to replace the old "clear" ones (just to make sure no air was getting in) $8.
3. New fuel pump $155. Purchased after the primer pump didn't do the trick. What the heck, beats having the stock one go out 100 miles from home.
And all along, it looks like it was just the shutoff diaphragm that was stuck.

Check for oil in your brown vacuum line, when the shut off switch goes south oil will get in the lines and trashes your switch at the ignition. I have a small in line fuel filter in the vacuum line to detect any oil.

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"