I resealed just one delivery valve and can not start the engine any more. Before the reseal the engine would start right up. Noticed that the preglow light does not comes off after several seconds as it did before. Just stays on. I checked the voltage on one glow plug and it seems to be be present when I turn the key on. Tried to loosen the injection line on the injector which DV was rebuilt and there is no fuel is coming out when I crank the engine. So far, I drained the battery twice and no start. It looks like the engine is trying to start if I do not push the gas pedal when cranking. If I push on gas the engine shows no signs of life. The car is 1987 300TD. Any ideas? Thanks

 

Did you bleed the air out?

 

I tried to loosen the nut on the injector that had its DV rebuilt while cranking. No fuel came out. But the other 5 fuel lines were not touched at all.

 

Do you have fuel at the other injectors?

 

Will try to see that tonight. The battery is dead, so I can not even crank the engine. My assumption was that since I did not touch the other delivery (pressure) valves, the fuel should still be there under pressure and I will be able to start on 5 cylinders with no problems. Am I wrong?

 

I'm not going say that youre wrong, but, anytime I open the fuel system I try to bleed it.

 

It looked like only the fuel that got out was from the delivery valve I removed. The amount was tiny. I did not feel like I am releasing any pressure from the system. I specifically wanted to remove one valve at a time to avoid this problem and yet I got it anyway. Glow plug relay behaves strange as well. It is supplying the voltage to the glow plugs, but the light does not go off after several seconds as it did before. The weather is warm in LA, so few seconds all it took in the past. I had no troubles in the past starting the car once the glow plug light goes out.

 

Does the glow plug light go off eventualy?
If air get into the fuel pump, then it has to be purged.
Charge the batt. and then see if you have fuel delivery to the other cyl.
If the battery is weak then the glow plugs could be pulling power away from the fuel control valve and that might prevent any fuel delivery

 

See if you have fuel in the fuel filter if it's low or empty it is loosing prime.

 

One more thing, think of the diesel fuel injection system like hydraulic brake system.

 

The glow plug light does go off, but I think it is related to the safety shut off. I hear a loud click in the glow relay and the light goes off. It happens after about 1 min. Which one is the fuel control valve? Is that the one that is controlled by the vacuum thru the "ignition" switch? My car is 1987 300TD.

 

The prefilter does have some air, but is about 3/4 full. It was this way before. I did not see any air bubbles. The fuel return line (at the main fuel filter) is empty. Thanks a lot for all your help. I am new to diesels. I knew they are hard to start sometimes, but hoped I will be more lucky than others. Aren't we all think this way?

 

Ckeck to see if you have any vacuume lines disconnected between the fuel shutoff and the brake booster( brown line) and the brown/ blue line at the pre glow plug switch.

 

and yes you are correct about the shutoff valve being vacuum operated, I mixed up injection systems thinking that fuel shut of was electric.
If the fuel control valve is in no fuel positon you will not get any fuel delivery to the injectors

 

Does it shuts the fuel off by applying the vacuum, or it needs the vacuum to let the fuel go to the pump? I will double check the lines.

 

it needs vacuum to let fuel in.
Check the vacuum supply(pump), starter switch or the brake booster valve.

 

Just checked everything. What I found is that when vacuum is applied to the shut off valve, the manual shut off level goes gown, closing the fuel delivery. If I turn the ignition key to position II (on) the vacuum is disconnected from the shut off valve and the lever pops up. I think the vaccum is appled to shut down the engine. I tried to start the engine again. It tries to start, but can not hold. Up to two cylinders try to fire up. If I push on accelerator, it dies right away. Battery is dead again now

 

Sorry for the misinformation on my part,I guess I misunderstood what I have read about your fuel sytem.Anyway, if its trying to start , that means it's getting fuel

 

I opened the glow plug relay today. Here the story. I was working on the power window that was stuck. To test it I had to turn the ignition switch on and off many times. I realized that I am draining the battery very fast because each time I turn the ignition on I engage the preglow system. Finally I disconnected the 6-pin plug at the preglow relay. The one that goes to the glow plugs. Do not remember now if I noticed some blinking of the preglow light before I disconnected the plug or after. I continued to debug the window. The window got fixed, but the battery was drained completely. The battery is old and does not have great capacity. While charging the battery I started to work on the delivery valve. I resealed only one valve, replacing the seal and the copper washer. Now, the preglow light does not go off until about one minute after the turn on. I think that is the safety shut off. I can not start the engine. Inside the relay I found a spiral wire wrapped around a (termo switch)? That is connected in parallel to the glow plugs. Does this heats up with the glow plugs indicating that the needed temperature is reached? The relay looks very complicated inside. All that electronics is probably to monitor the current thru the glow plugs and indicate the fault. Of cause I measured the resistance of all glow plugs at the socket and found it to be 0.6 Ohms. If my plugs do not heat up really good, the engine will not start. There IS voltage at the plugs. I checked it. I also checked the the voltage is rising with time, indicating the dropping current as the plug heats up. i saw about 10.4 V max. My only guess is that I do not have enough current to heat up the glow plugs. Does anyone have a spare glow plug relay and would let me to test and eliminate this problem?

 

If your battery is weak then take care of that first, before you start chasing the glow plug system.

 

Happy to report success! Started the engine today. After charging a spare battery overnight it barely had enough juice to start the engine. I was measuring the voltage at the battery all the time. It was 12.8 V when I started, dropped to 11.4 V "ignition on". Probably preglow plugs work fine Waited 10 sec - spin the engine. False start. Repeat. The voltage now is about 12.5 V falling to 11.2 V. Same story. Repeat. couple more times. The final voltage on the battery was 12.3 V going down to 10.96 V with ignition on. I was spinning the engine for about 20 sec each time and about 30 sec on the last attempt as the engine caught on on 2 or 3 cylinders so the battery and the starter load was reduced. Still a little rough on idle, BUT the cylinder that was misfiring constantly on idle before is working now! No more hard shaking on idle. I hope that my DV valve rebuilding solved the problem. Now back to the glow relay timing issue. Still there. The light does not go off before the engine started, but does go off when the the engine is started. Assumption: glow plugs are still good, timing mechanism died. What can it be? There only few chips inside. A capacitor? Thanks a lot to everyone who helped. Back to debugging other issues. At least I know that the engine still works

 

Good news. I think these cars need a battery in top condition to perform properly.There is a lot of electrical load when compared with an older vehicle.