87 300TD 603 no start

[dieselnut14]

Hello to everybody,
I am trying to trouble shoot my friends turbo wagon. it will crank but will not start. On occasion it will start right up and run fine and be good for a day or so and the will go right back into no start.
1. glow plug circuit good and all glow plugs working
2. new fuel filter, old one was still good
3. full tank of fuel
4. if engine does start, it starts as if the fuel filter was just changed and there was air in system.
5. no fuel leaks, or any sign of air in system.
6. can sit a day and just start right up. can run for an hour and not start
7. no trap oxidizer, removed and replaced by mb 2 years ago.

I myself have a 123 and no electrical extras on the ip or the mass air flow in the air intake.
Does any body think something like this could be electrical ie; electric shut down or mass air flow circiut.
Any suggestions or tips on trouble shooting this one would be very appreciated.
Peter

[Brian Carlton]

There is no electrical issue on that vehicle.

These intermittent conditions are certainly the result of a lack of fuel. Cannot be the fuel pump........otherwise it will never start.

And, it can't accumulate enough air in one or two hours to prevent a start after 10-15 seconds of cranking.

So, I'm inclined to think the tank vent may be to blame. When it won't start, open the fuel filler cap and see what happens.

The SD did the same thing to me once. Never happened again............

[sixto]

What's the position of the engine stop lever when it won't start? Does holding the stop lever upright allow the engine to start? Does the engine start with the vacuum hose disconnected from the shut-off actuator?

Sixto
93 300SD

[BenzDieselTuner]

agreed, the problem may be a "stuck in the off position" shutdown actuator....

[Hatterasguy]

Originally Posted by sixto

What's the position of the engine stop lever when it won't start? Does holding the stop lever upright allow the engine to start? Does the engine start with the vacuum hose disconnected from the shut-off actuator?

Sixto
93 300SD

Thats what I was thinking.

[speedy300Dturbo]

Fuel Leaks on top of the IP.

[dieselnut14]

Good morning,
Brian took your advice and still no go.
I removed fuel line at filter from the fuel pump, I had a helper crank the engine and I had fuel but I do not think the pressure was all that good nor was the volume.
I cracked a high pressure line and cranked the engine and no fuel.
I removed the fuel line that goes to the ip and again cranked the engine and there was no fuel at all.
Question, who knows how much pressure and volume from fuel pump should there be, any suggestions? thanks again,

Peter

[Brian Carlton]

Originally Posted by dieselnut14

Question, who knows how much pressure and volume from fuel pump should there be, any suggestions? thanks again,

Peter

If you remove the line from the pump and crank the engine, you should be covered in fuel. Not sure of the specification for it, but, you'll see fuel everywhere. It does sound like the fuel pump has insufficient or variable output.

However, this does not concur with the intermittent nature of the problem. If the pump is NG, the problem does not typically disappear.............

[larry perkins]

try this, use a clamp(i use a pair of vice grips-needle nose type) to squeeze closed the rubber return line from the fuel filter to the fuel tank.
if engine starts and runs like it should then you have a open pressure valve ,its on the ip the line that returns the excess fuel from the ip to the fuel return.
let us know.
also i have never let one run long,maybe a couple minutes with the line clamped,suppose it could build excess pressure and pop a rubber line.
larry perkins 92 old cars

[dieselnut14]

Hello,
Larry I did what you suggested and I did get it running, could not tell if it was at full power though cause it was stone cold, I did move it around in my friends driveway with no problem and it did not stall.
Now the dilema, as Brians suggests I should be covered in fuel when when testing the fuel line from the fuel pump. If I where to guess how much fuel was pumped it was about 2-4 oz in about ten seconds.
Now, it did start and run with the return line clamped off and after I removed the clamp it continued to run with no problem.
Now its a toss up, is there any other definitive test to be sure that it could be the check valve or the pump. Both are plausible defects that are exibiting their symptons. I would hate to replace the pump and have it be a check valve and vise versa. anybody else out there ever have the same problem, let me know.
Thanks everybody for your help.

Peter

[larry perkins]

if the pressure valve is open or opening early there isnt enough pressure inside the pump to allow fuel to the pressure plungers so you cant get any delivery. just take the clamp off and most times a fresh start will display a rough running engine or it just wont start.
if i get more than one test that fails then off come the pressure relief valve and a new one goes on. i have seen at least 5 bad valves in the past couple years,new one fixed them all.
larry perkins

[Brian Carlton]

Originally Posted by dieselnut14

Now the dilema, as Brians suggests I should be covered in fuel when when testing the fuel line from the fuel pump. If I where to guess how much fuel was pumped it was about 2-4 oz in about ten seconds.

The spec is a minumum of 9.9 ounces/minute at cranking speed. So, I'd say that you've definitely got that if you're pumping 3 oz. in ten seconds.

Therefore, the pump is ruled out as a culprit. I'd follow Larry's advice on the pressure valve.

[Wolfsburg]

Here is another thread which I started because of a no start condition on a 87 300DT. Mine in the end was a plugged cat.
87 300 DT No Start

[dieselnut14]

Hello,
On thurs ran the engine again and it started fine but with a different sound, as if it had no oil to the top of the engine. Of coarse I checked and had good pressure on the gauge and looked up top and had plenty of oil being supplyed up top.
The last tank of fuel I believe was ULSD and that is when this no start first appeared. I had some howes diesel treatment so I dosed it with about 12oz. and took it for a ride.It took about 10 minutes and the noise went away and the engine sounds as if it were new.
My only guess is that Larry was right and the relief valve was stuck and now it seems to me that it freed itself for good.
The car has been driven all weekend with no problems.
Thanks guys for your input.

Peter

PS. I am trying the bosio nozzels in my 84 300d, I will report on them as soon as they break in.

[larry perkins]

my oldest son just called fron charleston sc,he had driven a 92 300d to tampa from louisville took a boat ride for a week and returned to sc to visit his daughter.
i got a call at 4 pm, car just cranks and never fires,after a couple things varified,fuel in tank,glow plug light, i had him squeeze the fuel return line and the car started up in about 3 seconds of cranking,took the pliers off return line and engine quit.did complete cycle 2 times and the engine would keep running,so just talked to him and he is in spartansburg sc and car is doing great.
u know i will replace the pressure relief valve on the ip, but i am starting to believe this new fuel might be cleaning the ip a bit.
larry perkins