81 Datsun 720 SD22 Diesel

[Hawk_91119]

OK, I said that I used an electric fuel pump, meaning I skipped the mechanical lift pump. I understand what the lift pump is. I just connected the electric pump straight into the fuel filter and then it would go out of the fuel filter into the injection pump line. So you are saying it is unlikely to be able to prime and start with an electric pump? I have seen this guy on YouTube do that and it ran fine with the electric pump, so I thought it would work. (I cannot insert video) 

URL:  https://youtu.be/SweAGsYi7z4

[Hawk_91119]

Part of the problem may also be a bad starter, it turns over fairly slow even with a battery with almost 900 cranking amps. Why is this? The truck is rusty, but the connections look good. I have heard diesel engines need a lot of amps to turn them over, but it seems a lot of power for little results.

[wayno]

21 hours ago, Hawk_91119 said:

Part of the problem may also be a bad starter, it turns over fairly slow even with a battery with almost 900 cranking amps. Why is this? The truck is rusty, but the connections look good. I have heard diesel engines need a lot of amps to turn them over, but it seems a lot of power for little results.

 

Keep this in mind, never turn your diesel engine over long enough to make the starter hot, also do not turn it over with a half dead battery, it is very hard on the armature, and it kills them/they turn slower, I learned this long ago.

Edited April 14 by wayno

[Hawk_91119]

OK.  What about the mechanical lift pump, is it mandatory to use it instead of the electric pump? 

[wayno]

I have no idea myself, never tried running one on an inline injection pump, seems like Nissan would have that way in the first place if it were the best way.

 

I have started several old diesel engines that sat for years before buying them, some were very surprised to see it start, I primed them and made sure the glow plugs were getting power, they started, but they had not had someone not knowing about them messing with them.

[Hawk_91119]

I am now to priming the system, and I need some instruction. I am now just using the factory lift pump, no electric pump. I just now read that you should turn the key to the on position when you pump the primer, or else there will be air and no fuel flow. All the air has to be out of the lines, even the return lines?

 

I am getting fuel now to all four injectors, but it still will not run. I feel as if I am getting inconsistent fuel flow. I have not cracked any fittings, and I have not checked any screens. Are the bleeders, what you call banjo fittings, the fittings on the side (one in front and one in rear) of the injection pump?

 

My truck does not have a pre-filter. It has the big fuel filter, a Purolator, which I am going to replace. Do you think the system needs primed better, or does it have clogged injectors or somewhere in the filtering system? Could it be water in the fuel not letting it start?

[wayno]

There have been times when my engine would start but die after priming the shit out of it, when I prime and bleed I first fill the spin on filter full of diesel fuel, then the first thing I bleed is the banjo fitting going to the injection pump, the next one is the one on the front of the injection pump, I suppose you could remove the shaft going from the engine controller to the injection pump, this will put the injection pump to the run position, turning the key on will not do this because you have to have oil pressure for the injection pump to move to the start position, so removing the shaft from the injection pump is the easiest, when you do that make sure the shaft rests on something that will not have it jamb on something, it could ruin the controller.

 

Another thing you have to check is to make sure the glow plugs are warming up, the easiest way is to get a test light, connect the small alligator clip to #1 glow plug(front glow plug), then put the light point on the negative post on the battery, it should light up when you turn the key on, if it does not light up the glow plugs are not getting power to start the engine, it will not even try to start if the glow plugs are cold unless the engine is already completely warmed up.

 

For a last resort I will always remove that controller arm from the injection pump, I then know that system is not the issue if it will not start, you can test the system by removing the wire from the oil sender, then when you turn the key on the controller should move the injection pump to the start or run position, I cannot remember which position it moves to when this oil sender wire is removed, I work on my trucks/engines by myself most the time so I choose the way that takes as many possible issues out of the big picture.

 

I do not use either very often, it can possibly hurt the engine, I only use it to test an engine to see if it is firing, most the time I have used it was on an engine that had not been ran in years, using either is a last resort for me, when I use it I only give it a very small quick shot, I have never held the spray on while trying to start it, just a quick shot, then try starting it seconds later, I have run in front of a semi-truck spraying either into the intake while the semi was coasting down the hill in gear trying to start it, it cannot over rev in gear.

[Hawk_91119]

I went out to the truck today. I decided to just use the factory tank so it would not introduce air into the system when I took away my fuel can. I undid the drain plug, and the diesel in it was clean, so I filled it with 5 gallons of diesel. I replaced the fuel filter and put diesel in it. I used the hand primer pump and got fuel past the new fuel filter. The thing is, the front two injector lines will not prime. I was getting squirts of fuel out of the rear two injection lines. I opened up the first injection line on the pump side, and nothing is coming out of the pump, which is odd. I believe I was getting fuel out of it previously... I have not cracked the banjo fittings yet though, I have been trying to avoid that. I almost killed my battery just cranking the engine