I need some help troubleshooting my 240D that won't start. I have checked the glow plugs and they all have resistance across them and they all get about 10V when they are glowing before start. I don't know where to look next. The glow plugs were replaced 5 or 6 years ago so I don't think that is necessarily the problem.

The car seems to stumble when you try to start it but will not finally start up. Where do I look next? I'm not sure how to troubleshoot diesel fuel delivery problems or injection timing problems.

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George Carstens

Five or six years ago? I would pull the plugs and put 12v to them too be sure they are glowing. Most common "rough/no start" situation is GP related so make SURE they are good.

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Glow plugs should have very little resistance. I would think more than 10v also, but I have never measured mine.
You need a strong battery too. Make sure this aspect is goo, then check fuel delivery.

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83 SD

84 CD

I made a little bit of progress. I while cranking the car, I disconnected the vacuum supply line to the interior and used my Mity Vac and pulled vacuum on all of the engine lines. The car fired right up when I did this.

What did I do?

Is the fuel mixture adjusted with vacuum in some way?

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George Carstens

Something very odd going on here. Try removing the vacuum line from the shut off valve and see if that makes it start. Your description suggests that the ignition switch is not releasing the vacuum it puts to the shut off valve to turn the engine off.

No vacuum fuel adjustment apart from the shut off.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

^^Yes, now it seems as if the ignition switch is "telling" the fuel shut off valve to shut off, it's job when the key is turned off. It is a hard brown vac line connected to a rubber line coming off the shut off valve, pointing toward the firewall. Remove that line, and try to start.

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83 SD

84 CD

It seems I was incorrect about the shutoff valve. I pulled the vacuum line today and the car still wouldn't start easy. Can anyone verify what voltage I should have at the glowplugs? If I pull them out and check them, what should I be looking for?

George

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George Carstens

The best way to check them was noted above in this thread. You have to remove them and apply 12V to see if they really glow. I've found many plugs which test OK for voltage but don't glow. The resistance of the plugs is too low to measure accuraly with most common meters (unless you have a conductance scale in Siemens). Search other threads about reaming the glow plug hole before putting them back in.

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Steve S
Support Tech
UnwiredTools, LLC
www.unwiredtools.com

1982 380SLC
1994 E320TE
1998 E300DT

A digital multimeter should show less than 1 ohm resistance on a good plug. Higher than that and it is probably bad.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I'll check that. Is there an objective way to adjust the fuel mixture. The car seems quite a bit smokier than usual. Could that be causing the starting problem?

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George Carstens

Black smoke is an indicator of a plugged air filter.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

Maddog,

When cranking and the GP are not working, white fumes should come out of the exhaust. This is unburned fuel. No white fumes, engine is not getting fuel.

P E H

I still can't seem to get the car started. Since the car has been down I have taken the intake manifold off and cleaned out all of the carbon build up from EGR. I did indeed have two bad glowplugs so I went ahead and replaced all four and checked to make sure that they are actually glowing. I am now wondering if I might have a fuel delivery problem.

I removed the hard fuel lines to all of the injectors, one at a time, and cranked the car and only got a drip of fuel to come out at each injector while cranking. Is this normal? I know I need to do a compression test on the engine but don't have a tester yet.

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George Carstens

I checked a few more things while I was at it. Fuel delivery seems OK out of the pre-pump and out of the main fuel filter. It probably wouldn't hurt for the main filter to be changed though.

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George Carstens

Maddog,

Before U change the fuel filters, take off the line to the IP, crank the engine and see how much fuel comes out of the line going to the IP. It should be a good flow, possibly pulsating from the fuel pump. U could also pump the manual primer pump and observe how much fuel comes out of the removed fuel line.
P E H