87 300td no start - PeachParts Mercedes-Benz Forum

Bernhardt · #1 04-24-2016, 10:05 PM

Have an 87 300td that I've been having the no shut off with key issue for a while now. Today it decided to not start. Cranks over and glow plugs are getting power. Acts like it has no fuel. Fuel line has fuel in and fuel comes out if cranked at filter inlet. None comes out of an injector line when cranking. Currently a little stumped.

vstech · #2 04-25-2016, 12:26 AM

Most likely you have leaking dv seals. And you are having issues repriming the IP.

Another possibility is the shutoff valve has failed and is holding out the fuel.

Is the stop lever rising when trying to start?

If it is, you have lost prime in the IP.
Loosen all the injection lines at the injectors then unplug the glow plug harness from the relay, then fully charge the battery, and crank the motor about 30 seconds and see if any fuel comes out of the line closest to the firewall...

Bernhardt · #3 04-26-2016, 03:25 PM

Thanks VS. It's actually my sister's car. After posting, she tells me the fuel gauge always reads full, and that it's possible it's out of fuel. Have to admit the amount going into the filter seemed a little low the other day when I cranked it. Put fuel in, and am charging battery now.

Lever on pump seems to be higher than normal.

Bernhardt · #4 04-26-2016, 07:27 PM

Got it started. It was out of fuel. Now to fix the no shut off with the key bit. Get no vacuum pulse to the pump when the key is shut off. At idle, the parts that I think go to ignition key have about 15" of Mercury vacuum on the away from key side. Can't pull a vacuum with a pump on line going to the pump(can move lever on IP with hand held vacuum).

jay_bob · #5 04-26-2016, 08:26 PM

Double check the tubing elbows are not cracked. BTDT

Also confirm you are plumbed exactly per the service manual.

vstech · #6 04-26-2016, 10:15 PM

Post pics of the tubing you have by the ip, and fender. I'll compare it to one of my TD'S see what you have going on.

babymog · #7 04-27-2016, 09:10 AM

vacuum lines reversed at ignition switch?

Bernhardt · #8 04-29-2016, 05:38 PM

Been away from car for a couple of days....Anyway, it used to shut off with the key.

Car wouldn't start again. Got it going, to find it was sucking large amounts of air, which I know can lead to a no start from my VW diesel pickup. Hose replacement time time, since I could turn a bunch of them, and I have no idea when they were replaced - at least 4 yrs ago when the car was purchased.

Bernhardt · #9 05-01-2016, 01:10 PM

Well, I got rid of the air leak, and got it started last night. Ran it for about 15 minutes. This morning, no start again.

Yes, I'm having issues repriming the IP. So what and where are the DV seals?

Bernhardt · #10 05-01-2016, 09:58 PM

Nevermind the DV seal question. Found the answer on you tube. I can hardly believe it popped right up. Thinking that the small amount of fuel I detected this afternoon leaking out in that area from one line is the source of my issue. If fuel can go out, air can go in.

babymog · #11 05-02-2016, 07:12 AM

Park it full of fuel and/or nose low, often the fuel leak will drip so that you can find it, and the bonus is that it'll start.

I don't believe that DV seals will cause a no-start. You are probably looking for a leak on the low-pressure (suction) side, from tank to lift pump. If it is downstream of the lift pump it should have fuel in the IP and start (although DV seals can cause it to idle rough) and the lift pump will continue to supply fuel for it to prime/run.

Most common points are the rubber line junction from metal (before the small filter) and the fuel heater. The fuel heater can be bypassed temporarily, especially in warm weather and is easily re-sealed.

Bernhardt · #12 05-16-2016, 09:15 PM

Grrrr. Had a post written and system rejected it even though I logged in.

Anyway, been away from working on it until today. An electric fuel pump will happily pull fuel from the tank with no indication of air. Got the intake manifold & injector lines off. All of the injector lines had fuel in them when I cracked the IP end of them as evidenced by the fuel flowing out. Still need to replace the DV o-rings as one of them leaks when the engine runs. Anybody have any other thoughts as to my no start after sitting overnight? Was 15 minutes of basically idling not enough time to properly purge the IP?

Anybody have a torque value for the Delivery Valve?

vstech · #13 05-16-2016, 10:04 PM

DV seals will definitely cause a no start... Gotta open all injector lines, unplug glow plugs, and crank until fuel refills the ip and lines... Really drains the battery...

Bernhardt · #14 05-17-2016, 03:14 AM

Got the DV seals replaced. No fuel in the DV well if you will when replacing. Left one loose and used an electric fuel pump temporarily plumbed in between the hardline on the body and the prefilter to prime the IP. Once I had fuel coming out the loose one, removed the electric pump, hooked up the injector lines and fired up. Only took 3 or 4 extended cranks in all to get it fired up. Will see in the morning if the DV seals were the problem. At least the leaking to the outside one doesn't anymore, which needed to be done in either case. Venting air through the injector system doesn't seem like an efficient way to get rid of trapped air in the IP. Is there a vent screw on this IP? The rotary Bosch VP unit used on the early VW diesel used excess fuel return that's mounted on the top of the pump for this function.

Bernhardt · #15 05-17-2016, 03:18 PM

It fired right up this morning like it should, looks like the DV seals did the trick.

On to the no shut off bit. Found a couple of vacuum line issues - a couple of disconnects by the firewall & under dash. Accidentally pulled one loose that I haven't reconnected yet, but have strong vacuum(~25" Hg) going to the shut off diaphram. Lever moves, but not enough to shut engine off. Using hand pump, can pull max of maybe 5" Hg by pumping quickly. Bleeds down that fast. Thinking diaphram maybe shot. Doing a search on R&R of that now.