Another quick test perhaps is to check for any fuel output from the return line at the injection pump when cranking. Even a bit is okay. That of course after the car has sat long enough to present the problem. If totally dry I would check my low pressure fuel supply system out totally. Yet the lift pump output test is still important in my opinion.

Since the only anti return fuel valve in the system is also in the lift pump you might be backdraining from air getting in somewhere and having to pump fuel back up. So until the fuel reappears the car will not start. Just things I might consider.

ugh
 

still no go - hard starts and immediate death at idle RPM's

1. tested lift pump.....got a few inches of diesel in a gallon jug after cranking with line disconnected.

2. ran a bottle of diesel purge thru (had to start on wd40). the unused diesel purge coming back really wasn't dirty, l like I would have suspected.

3. replaced amber line with rubber fuel line.

4. I urinated on the hood to make myself feel better. still didn't start.


any other suggestions?

and sheesh, I called out that boston-sports-loving, affable chap and he didn't even react? I should have known better - he won't stray into diesel discussion. :D I even poked @ Chad in another thread and nary a response. You guys are getting lazy in your old age.

Will the engine run at idle speed if the operator maintains throttle input? Or, will it just not run at speeds bellow a certain RPM, regardless what the operator does with the throttle in an effort to keep it running at idle speeds?

Also, I think this was asked, but when you perform a cold start, how long to you let the glow plugs glow for, and what, if anything, do you do with the throttle while cranking?

yes - if I keep on the accelerator, it will run...even at low RPM's. It definitely lopes and runs rough though. As SOON as I let off the pedal, it dies.

after that - it's either very hard to restart or impossible (unless wd40 is snorted).

I glow the plugs like always....wait until the light goes out and then I usually count to 10 before starting (but before I hear the relay click).

the craziest thing is....is that I wasn't fiddling with anything before this happened....the IP advancement, the idle adjustment, vac. line stuff....this was all induced via the fuel or at least I presume. Hahah...alternative fuels can suck it.

May be time to do a power balance test if you can keep the engine running. Plus some kind of direct fuel feed with an external fuel supply to the injection pump if the balance test leads no where. Or cannot be accomplished. Gotta start narrowing this problem down...

Let's start cheap
 

Let's start this by going cheap.

First check for vacuum at the vacuum shut off. Simply pull the line off the vacuum shut off valve and run the car. If it does not shut off at idle the switch is leaking by vacuum to the shut off.

A bit messy but see if it will idle without the oil filler cap on. If the crankcase is building too much pressure from blow-by (worn rings) the crank case vent may be becoming plugged. The increase in crank case pressure will cause the vacuum shut off to actuate from crank case internal pressure.

Next check throtle linkage and idle speed set located behind the injection pump. It has a lock nut on it. Very rare but it could have backed out.

Next It would not cost much but time and a valve cover gasket to check valve lash again. You may have them too tight!! Remember 3,000 miles ago when they were adjusted in cold weather and the book said do it at 60+ degrees??


Let us know what ya find, other than $300 for your car.

I didn't read it all but scanned. You did change your filters, right?

all good suggestions - and thanks fineolbenz. I'll check the valves again (I did the vac test already) and the clogged crankcase vent....at this point, I'll try anything.



silly slipshod architects:)

haha, I kid I kid. Yeah - I didn't expect anybody to slog through my verbose backstory...and I probably shot myself in the foot for getting help too.

Yup - changed both filters, multiple times.


and I need to re-read Barry's advice....he's clearly on a different plane of intelligence, I don't even know how to tackle that one:)

Read for information in the archives. For example a 240d with an under prefforming cylinder may not idle. Or an injector pump getting too much air mixed in with the fuel may also become problamatic.

A nice separate fuel feed to the injection pump would eliminate any pre injection pump problem. You can feed the pump by gravity.

Power balance tests just establish that all cylinders are contributing to the running of the engine basically. Or they are not. If a weak firing cylinder is detected there then becomes a systematic approach to find the problem that causes it.

Normally the nut is loosened and tightened on each injector. One at a time. This is to determine if each cylinder in turn is contributing it's share. If one is detected to make no differance you have something to help you isolate the actual problem.

Difficulty starting. Air leak in fuel system?
 

Dear all,

This is my first post so please be patient with me if I forget or overlook some required rules of forum etiquette.

I have a 1983 Mercedes 240D (manual, 4 speed) and back in April 2009, I had the vacuum shut-off pump replaced (the engine wouldn't turn off when I turned the key and pulled it out of the ignition). Since this vacuum pump was replaced, the car now shuts off properly, but ever since that repair, the engine has been difficult to start.

It takes at least two or three attempts before the car will start, and it NEVER starts on the first attempt, no matter how long you crank it. Once started, it runs fine, but this has NEVER been an issue until after the vacuum shut-off pump was replaced. I fear if I don't get this fixed, I'll end up putting undue strain on my starter, etc.

Does anyone have any idea what the problem might be and, of course, how I might be able to fix it? I'm guessing it has something to do with the vacuum shut-off pump system (perhaps it's pulling fuel back too far with too much suction?), which is why I was reading this post (the problem sounds kind of similar to the one described here), but I'd like to ask some of you out there who have more experience.

I thank you in advance for any advice you can offer, and please let me know if you need more info! I'll be happy to provide it. And I must admit that I'm not experienced at car repair. However, I am not afraid to try certain things, and for what it's worth, I do have a Hayne's manual for the car.

Thanks! :)

P.S. This is a couple of unrelated, but quick questions: Just this weekend, I put a diesel fuel treatment/fuel injector cleaner into the tank, and the next day fuel started leaking from the rubber stopper on the fuel injector closest to the firewall (at first I thought it was the fuel injector hose, but it turned out to be the rubber stopper that had lost its seal).

My question is this: Does the fuel injector cleaner/diesel fuel treatment dissolve the rubber parts in the fuel line? Do you think the diesel fuel treatment/injector cleaner caused the rubber stopper to lose its seal? And should I be prepared for more rubber elements in the fuel system to fail in the near future, or was this just an unfortunate coincidence?

Again, many thanks to the forum members in advance.

You may want to start a new thread.
First, unplug the vac connector to the shut off actuator, a brown vac line going to the injection (fuel) pump. Try and start the car, any difference?
Those fuel lines age like everything else, replace 'em all at the buy parts button at the top of the page.

imagine that?
 

They say time heals - but apparently my old 240d doesn't care much for empty platitudes. Just dusted off my MB (in the garage since my original post) w/ the foolish hope that THIS time I'll conquer it....

Nice to find this thread, however - review what steps I've already tried....and see that all you crazy diesel cats are still holding it down.

Add a new starter + IP timing + valve adjustment to the list of straw grasps! I'm seriously starting to wonder if the entire fuel pump assembly isn't sucking air....the gallon of fresh diesel that I'm pulling from (again started on wd40) looks milky or aerated after coming back out the return lines.

How common is an air leak that doesn't drip fuel?

Fairly common in my opinion. Running on a container of fuel see if the fuel coming out the return line of the injection pump has bubbles in it. Or even using the current system see if they are there.

The best methology is to submerge the end of a line from the injector pumps relief valve in some fuid as this really indicates air going through the system. There really should be none present. Fair amount or frothy as you describe and that would easily account for your hard start and no idle difficulties. Usually cheap to repair.

thanks for your patience/advice back then...and today; assuming of course that you've added a number to your name!

I'll submerge the line in fluid and crank tonight - I have a black rubber line on the outlet side of the IP now so I can't really see in situ.

I also wouldn't describe the fuel in my container as frothy - but milky...I don't really see any bubbles or even microfoam like in a fancy latte? I'm pretty sure these are the sappiest adjectives ever used in this forum.

SO - if bubbles; do I replace the essentially new (bosch) primer pump that isn't leaking fuel?

How about a (really short) recap to say what the problem is?

I'm a lazy new boy who really can not be arsed to read the whole thread - despite your witty style and jovial approach to automotive frustration.