Hi all,

My 87 300d has been giving me some trouble recently and posts of similar problems on this forum and others have been helpful for troubleshooting but not resolution as of yet.

Essentially, my problem is that the car acts like I've just put in a new empty fuel filter when I try and start it after letting it set overnight. I have to crank and crank (pedal floored) probably 6-7 times for 20 secs each, until it fires up. Once its running, it idles fine and runs like usual.

I've replaced the fuel filters in case of a clog and checked fuel at injectors and top of fuel pump. My thought is a pinhole leak in a fuel line or maybe a seal in the injection pump. However, lines look good and there are no visible fuel leaks under the hood.

Any thoughts would be great.

Are you 100% sure there are no fuel leaks under the hood? Can you smell diesel anywhere up there? If your engine compartment is not clean enough to visibly see it, you will need to wash the engine compartment first. What you describe sounds exactly like a fuel leak either at the injection pump, fuel lines, or fuel thermostat.

This is, of course, assuming that your glow circuit checks out 100%.

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Dave
Boise, ID
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Park the car facing down hill, the steeper the better, over night, with a full tank & see if you still have the problem in the morning.

Did you replace the O rings on the bolt on the secondary filter when you did the filter change?

I see you had glow plug problems a couple of years ago, how are they now?

Do you have a standard fuel system or some WVO system?
If you have a WVO system, you need to go to a forum on WVO and ask there. Those systems are a common cause of your problems. Much of the help that you will get here will be of little value unless you provide details of any modifications to the fuel system first.

Good Luck !!

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Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

thanks for the quick replies

gsxr -- I've cleaned the engine area and still haven't found any clear fuel leaks. That being said, I was hoping to have someone confirm that line of reasoning...I'll replace fuel lines tomorrow. Some of the lines are quiet obviously very old. As far as the glow system, GPs test out under 1 ohm and the relay is new. Have tried block heater as well for confirmation and the results are the same.

layback40 -- the car is using standard fuel. I can't say with complete certainty, but it does seem to start 'easier' with a full tank. Will follow your advice and post results.

Have a look at the edits to my post.

It is sounding more and more like a very small air leak. The fact it developed just after a filter change adds to this.

If you dont have the problem with a full tank, it could be the valves in the lift pump are leaking a little and allowing the fuel to drain back to the tank over night. This mainly occurs when the return line into the tank is returning the fuel above the fuel level in the tank, when the tank is full it doesnt happen.

__________________
Grumpy Old Diesel Owners Club group

I no longer question authority, I annoy authority. More effect, less effort....

1967 230-6 auto parts car. rust bucket.
1980 300D now parts car 800k miles
1984 300D 500k miles
1987 250td 160k miles English import
2001 jeep turbo diesel 130k miles
1998 jeep tdi ~ followed me home. Needs a turbo.
1968 Ford F750 truck. 6-354 diesel conversion.
Other toys ~J.D.,Cat & GM ~ mainly earth moving

Sorry for the delay. Had the opportunity to get to an un-oiled beach over the weekend and couldn't pass it up.

Anyways, I replaced the fuel lines and there was no change in startup.

Filled up the tank on Friday before I left and it started right up on Monday!!

layback40 -- whats the procedure for fixing the leaks in the lift pump?

Thanks again.

Hey Joe, Here's my 2 pennies:

I would put a clear fuel return line on to visually see the air in the lines. There's a return hose from the fuel filter back to the tank. Any 5/16" clear hose from the hardware store will work.

That will show you you have air in the lines.... which it sounds like you have.

Then from there you need to isolate where it's getting in. From the usual problems here's where I'd start and let it sit for the period it takes to act up and restart the engine Here are the steps in the order I'd try them:

1. Bypass the fuel heater. In other words connect the fuel supply line directly to the little clear pre-filter and leave it connected that way. Mine has been like that for the entire time I've had it because mine leaked there.

2. Run the engine out of a home-made fuel supply temporarily to see if there is a problem back from the engine compartment (i.e. fuel lines or the tank connectivity). Just a little background the pickup is a screen mounted at the bottom of the tank which is behind the back seat back support and under the 1st aid kit.

3. Check the banjo connections at the injection pump (the brown hard plastic lines) from the fuel filter.

4. Check the lift pump for leaks.

5. Check the little spill over lines on the injectors for cracks or leaks.

The last thing I'd suspect are the o-rings on the injection pump's delivery valves. These dry out and change shape and if they haven't been replaced are pretty much bad at this age (any piece of rubber that's 23 years old has lived it's life). My injection pump would leak air past these. It wouldn't leak fuel that I could see but the idle was rough. When I changed these the idle smoothed out and where it used to take 3-5 seconds of cranking it now starts at the touch of the key.

But first, clear return line is where I'd start. If you see bubbles, you're getting air. But again, if you have a rough startup, air is in there somewhere.

I'd bet $5 that it's the fuel heater.

But you just need to figure out where it is. It's so easy to run the engine out of a diesel can or milk jug that I usually will do that early on. Just stick the input side of the lift pump (the little hose the goes to the clear filter) into a diesel can. This will tell you if the problem is under the hood (not back to the tank or plumbing from the tank).

Anyways, hope that helps, keep your results posted here and I'll bet you'll have it fixed pretty quick.

I still haven't seen your car Joe! You need to bring it back with you sometime so I can see it.

Good luck!

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-E300d '99 350k
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-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
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-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.

+1 on this.

I was for some reason thinking that the problem was when the car was warm.

I just re-read and see that it's the first start of the day. Glow plug testing is pretty easy with a multimeter (harbor freight tool stores have them for $5 or less and they're red in color-they work just fine).

If the glow plugs aren't lighting you'll have super hard starts even in nice weather on the first start up.

The clear fuel line would be a good diagnostic to see if you have air in the lines.

Once again it's from the fuel filter return back to the to the tank steel line at the bottom of the driver fender wall.

__________________
-E300d '99 350k
-Suburban '93 220k
-TDI Jetta '03 350k
Sold
-F250 '96 7.3
-Dodge Ram 12V
-E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia MO Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's.