Adam,
It does indeed sound like you have more than an air leak going on. My approach would be to first get it running on "the bottle", then once it's verified that it WILL run, start re-attaching fuel lines.
Yes, there are two screens that can prevent fuel flow, but it seems this would show itself as low power and would not affect its ability to idle and to simply run. But here's the TSB that describes it.
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The pump has a cutoff solenoid.
INeedLUV wrote:
So Both the feed line and the return line go to the jug. I then try to use the bulb to push fuel through the injection pump and out the return line. First I try this with the bleeder bolt(that screws into a lager bolt) unscrewed a little. Fuel comes out the bleeder bolt, but it feels like it takes quite a bit of pressure with the bulb. The fuel in the return line did not move. Then I tighten the bleeder bolt down. Then I try to prime the lines more and push some fuel through the injection pump. I squeeze the bulb while watching the return line, but the fuel in the return line never moves. At the bulb, tt also feels and looks as though though no fuel is moving into the injection pump. The bulb is quite hard to squeeze, so it seemed like the lines were pressurized. So I don't really get why the fuel didn't come out the return line. Is there a screen between where the fuel can go out the bleed screw and out the return line? Is there some other problem that would prevent the fuel from passing through the injection pump.
There is a fuel cutoff solenoid that can go bad, but it's not likely.
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However, if the key was in the "off" or "acc" position when you used the bulb, it's normal to fell this resistance because the cutoff solenoid is "cut off". That would be my next thing to check. The cutoff solenoid should be the only thing on your pump with a wire attached. To bypass it, remove it from the pump and then remove the plunger and spring. CAUTION: the plunger and spring tend to remove themselves, so don't lose them! Re-install the solenoid without them. Just be aware that if it starts, you will need another way to shut it off because the key won't turn it off.
Test it with the solenoid gutted, and let us know what you find.
Jack
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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.comIsuzuPup.com