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d4 7u loses fuel prime after sitting for a day

d4 7u loses fuel prime after sitting for a day

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55HT4
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The other day I ran out of fuel in my old cat and it died. So I put some fuel in the tank and bled the fuel system, gave it a tiny shot of ether (tired engine) and it fired right up. I ran it for a little and parked it. The next day, it would not start, it lost it's prime and I had to bleed the fuel system again, next day same thing. Never lost it's prime before I ran out of fuel. Does anyone have any ideas?

Related unrelated note: The injector pump for cylinder 1 sticks and does not pump fuel when I crack the line going to the injector (I know that there is a vent on the back but I can't reach it because of the ht4 frame), is there any way I can fix this or do I just have to replace the one pump.

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Josh
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Sat, May 2, 2020 8:31 AM
D4Jim
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Could be several things causing it to lose prime but the first thing to do is check the oil in the crankcase to see if it is getting fuel into it. The oil level might be increasing, or the oil getting thinner from leaking fuel. The two main causes are a bad seal in between the tower and the injector pump or a defective transfer pump. Sometimes the relief valve (transfer pump) gets stuck and it will run OK but stays open to leak fuel when stopped. Seals in the transfer pump may be shot too. It either goes into the crankcase or it should come out through the small tubes. Those tubes often become plugged and the fuel goes right into the crankcase. Air has to be getting into the system somewhere. Be sure to check everything around the fuel tower for any possible leak.

My bet it is the transfer pump or bad seal between the injector pump and the fuel tower, but may be something simpler. Some others will chime in here with other ideas.

Make certain all the air is bled out of the fuel tower.

Cats Forever

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Sat, May 2, 2020 12:16 PM
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