no fuel in injection lines - PeachParts Mercedes-Benz Forum

tschepplmasta · #1 01-22-2003, 05:36 PM

since a couple of days my 1980 300D wouldn’t want to start. first I thought it was the cold weather. changed motor oil from 15W 40 to 10W 40, changed oil filter, changed diesel pre-filter, changed diesel-filter, pumped the hell out of my thumb (hand pump), checked battery, cranked til battery almost died, bought battery charger, charged battery, NOTHING!
searched forum, cracked one of the injection lines – NO DIESEL, even if I’m pumping the hand pump like mad! checked fuel line from the small fuel pre-filter to the actual fuel filter, pressure is pretty strong. removed screw from top of main fuel filter (where 2 or 3 fuel lines intersect), pressure also very good here when I’m pumping.
I don’t understand why there is no diesel in the injection lines then – anybody an idea? couldn’t find any leaks or so when pumping. where does all the diesel go when I pump and why isn’t there any in the injection lines?
PLEASE HELP!
this always was such a phantastic forum, I hope you guys can help me again this time!
thank you very much in advance!

T.

engatwork · #2 01-22-2003, 06:13 PM

Did you fill the spin on filter with diesel fuel or a diesel fuel additive prior to spinning it on? It does not sound like you have all the fuel system full. I would suggest getting a good charge, cracking ALL the fuel injection lines at the injectors and crank the engine over some, pump it some and repeat till you start getting some fuel out of at least one of the lines. Once you have fuel coming out of two of the lines, if the engine is healthy, button everything back up and it should start.
I did not quite understand one thing - was it running one day and then just would not start? Did the "no start" condition just come up all of a sudden or did it gradually get worse?

tschepplmasta · #3 01-22-2003, 07:50 PM

initially I didn't fill the spin on filter at all, but checked it - since I pumped a lot, its totally filled up with diesel fuel now. so that's not where the problem seems to come from. I even tried to crank the engine several times for a pretty long time already (with the new charged battery), but there istn't even smoke developing...
somewhere the system seems to be interrupted.
the "no start" condition came over night, i.e. all of a sudden. temperatures were pretty low, so I thought that was the problem, but now it seems to be something else...
since I already cranked the engine several times (even not with cracked injection lines) AND got a blue thumb from pumping the hand pump, do you still think it might help to crack ALL the lines & give it another try?
do you have any information about where the fuel line goes BETWEEN the spin on filter and the actual injection lines? maybe some part is clogged??
thank you,
t.

mercedesmatt · #4 01-22-2003, 08:56 PM

how cold is it there?? cold enough the fuel in the high pressure injections lines could be gelled???? you may want to take them all off and blow them out to make sure then reinstall leaving the nozzle end of the line loose, crank till fuel appears. something else to think about too, the engine is shut down by a vaccume circuit, this circuit works like this... the vaccume is applied by a valve on the back side of the ignition switch, through the brown plastic line, on the back side of the injection pump is a diaphram that the brown line connects too. you may want to unhook this line at the diaphram to make sure the valve hasnt failed and is applying vaccume to the diaphram, in turn pulling the rack into the no fuel position. hope this may help you out. good luck.

haasman · #5 01-23-2003, 01:03 AM

mercedesmatt may be on to something regarding the cold. If you have moisture in your fuel, it could have frozen in your lines. How cold is it there?

If you suspect this could be the cause, you can warm the whole area with 1) a hair dryer 2) an exposed light bulb 3) pour a lot of warm water over the pump, lines and injectors. Best would probably be the light bulb under some sort of a cover that won't get burned but will hold the heat in.

Haasman

tschepplmasta · #6 01-23-2003, 04:15 AM

when the car refused to start, temperatures were
around 0° or 5° Farenheit. I'll definitely remove the
high pressure injection lines and blow them out!
also will check the shut of diaphragm with my mity vac.
thank you guys, I'll keep you posted.
T.

engatwork · #7 01-23-2003, 06:04 AM

I imagine those temperatures have something to do with it

.

tschepplmasta · #8 01-23-2003, 12:17 PM

removed all high pressure injection lines - diesel was NOT gelled.
lines are okay. removed the vacuum shut off valve, but it was
NOT stuck in the "shut off" position, but I cleaned it out, since
there was pretty much OIL in it. (is this normal?)
put the vaccum shut off valve back in - and surprisingly, diesel
is coming out of the high pressure injection lines (cracked them
on top of engine)!

but: car still doesn't start! my last idea: the glowing plugs might
not get electricity?? since I changed all 5 of the like 3 months ago,
they should be ok. signal light also okay, but WHERE IS THE FUSE
for the GPs?
any hints greatly apprechiated!
t.

haasman · #9 01-23-2003, 12:43 PM

tschepplmasta

So you are getting fuel to the injectors?

If so, have you tried the "double-glow" starting procedure? The way I understand it, turn on the key and let the glow plugs go for about 30 seconds, even past the light going out. Turn the key off and do it again.

There were several postings recently regarding hard diesel starting in the cold weather. This is where the "double-glow" starting procedure came from. They also were saying that valve adjusts make a big difference.

It has been several years since I worked on diesels so I can't walk you through the checking of the glow plug electricals, but a quick way to make sure they are getting juice is to see if each of them get warm (hot) by touch.

Haasman

tschepplmasta · #10 01-23-2003, 03:04 PM

Haasman

thanks for your comment!
I even tried the "triple-glow" and "quadruple-glow" procedure,
without success.

just built a little device to test if there's juice going to the glow
plugs - all 5 of them are getting juice! I can't imagine they're
broken because I replaced them just like 3 months ago.
I don't really know how to continue now... any more ideas?
thank you!

t.

haasman · #11 01-23-2003, 03:22 PM

tschepplmasta

No problem. That's what we are all here for.

More ideas-

-Have you adjusted the valves lately? Critical on any car but especially with diesels to fire off correctly.

-In your owners manual, there should be a section regarding diluting the fuel for flow. I BELIEVE you "cut it" with 10% kerosene, but you should check that.

-Is it still very cold where you are? Putting a blanket over the engine and using heat lamps or something to warm it up will make a difference.

-How old are your glow plugs? Even if they are getting juice doesn't mean they are working like new ones. You can always pull them and take a look at them. Clean if necessary. If you shop around they can be had for not too much money.

-another idea is to get it into a heated (ideally) garage. Sometimes where it can up to above freezing. If it is simply directly to the cold and nothing else, this will work like a charm. Neighbor, friend etc?

-Finally you can use of can of starting ether. I know a lot of people don't like this solution (search the threads) but I had an old '79 240D with below marginal compression and I got it going several times this way. The idea is to spray some up the intact to get some sort of combustion in conjunction with the glow plug dance etc. There is also the direct disadvantage of light-headedness, watch out for the fumes. There is an old story of a truck who had a chunk taken out of the end of his nose- supposedly flooded the engine compartment with so much ether that he feel asleep, head down, as the truck started, into the fan.

Haasman

tschepplmasta · #12 01-23-2003, 03:33 PM

Haasman,

thanks again for the fast reply!

to be honest, I NEVER had the valves adjusted since
I got the car, and went a total of let's say about 20000
miles or even a little more. but why wouldn't it fire up
all of a sudden instead of taking gradually longer and longer
to start? can the valve adjustment go bad all of a sudden
if it's cold?
is it hard to do the valve adjustment myself? I have absolutely
no idea how to do that...

the second possibility I can think of, regarding your comments,
is checking the GPs again (they're only 3 months old), but it
might be more likely that it's the valves, what do you think?

t.

p.s.: the car wasn't used to cold weather before I got it - might
that cause valve disjustment?

haasman · #13 01-23-2003, 04:25 PM

t-

My guess is: the valves.

Let's suppose the valves were adjusted 15k BEFORE you got the car .... and you drove it another 20k or so. 35k is a LONG time for not being adjusted.

It isn't hard to do, but it is something that you either need to learn or be shown. Their are several repair books that show you. Best to use two specific 14mm wrenches made for the job.

Can you get it to a shop and have them adjust the valves?

Haasman

tschepplmasta · #14 01-23-2003, 04:30 PM

Haasman,

I'll try to take it to a garage then.

I already tried to shift the auto-transmission to "N",
but couldn't move the car...

hopefully that's
not gonna be the next problem...
thanks for all of your help and expertise!

t.

haasman · #15 01-23-2003, 05:17 PM

t.

You are welcome. The 300D's are great cars. Truly some of the best Mercedes has made. Get it running right, maintain it and you will love it!

BTW, have you seen this post? Diesel Cold Start

Keep us posted on how it is going.

Haasman

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