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Old 11-30-2003, 03:34 PM
Registered User
Join Date: Nov 2003
Location: Seattle
Posts: 3
Unhappy 300DT '87 won't start after fuel filter change

My first posting; thanks all for your help.

I changed both fuel filters on my 87 300DT and about 12 inches of fuel line that looked tired. The car, which was running fine prior to the maintenance, will no longer start. I have cranked it for many minutes hoping to bleed the system without any results.

The prefilter is clear, and it is full of fuel.
When I remove the banjo bolt from the line from the canister style filter to the injection pump, diesel comes out.

I have place this line in a cup and collected fuel with cranking, though I have not measured the flow rate.

The fuel came out, rather than shot out.

There is no fuel emited from the injection into the hard line of the first injector.

I am puzzled about what is going on. Is the injector pump sensitive to the delivery pressure and volume of the fuel pump? I went as far as using a small transfer pump to squirt some fuel directly into the injector pump to try to see some activity, but there was no flow out of the injector pump.

Any help would be appreciated.

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Old 11-30-2003, 03:58 PM
Registered User
Join Date: Mar 2000
Posts: 517
Check the fuse on the OVP relay, which is located in the electronics bay behind the battery. If the fuse is blown, replace it. Or the relay itself may be defective.

Alternatively, the injection pump fuel return line check valve, located on the right side of the injection pump, may be faulty.
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Old 11-30-2003, 05:20 PM
sixto's Avatar
smoke gets in your eyes
Join Date: Jun 2000
Location: SF Bay Area
Posts: 18,745
This seems to happen only to me but maybe you're the second in a million - is the stop lever stuck in the down position?

Next thing I'd do is crack all the injector lines to see if any get fuel.

95 S420
87 300SDL
83 300SD ... $1100, see cars forum
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Old 11-30-2003, 09:20 PM
Registered User
Join Date: Aug 2001
Location: Evansville, Indiana
Posts: 8,150
If you didn't fill the fuel filter, the IP is now full of air. Takes a while to get rid of it at cranking speeds.

Try cracking all the injector lines at the injectors (14mm) and cranking with the pedal to the floor for a while. This will help purge the air out of the pump. Be prepared to crank for a while, and to charge the battery at least once.

Once you get diesel fuel at the injectors, tighten the cap nuts and try starting. You should at least get it to kick some right away. It will take a few minutes to run smooth -- takes a while to get the air out of the injectors.

I always change fuel filters with a hot engine, it will crank faster and start easier.

1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!
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