Bypassing lift pump

scozzy

scozzy

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So I suspect my lift pump on my yanmar 1gm10 is suspect.
Am going to bypass it later today/tomorrow with line to injector via gravity fed jerry can bulb pump set up to test if it is indeed not capable of getting fuel right through the system.....
So the question is...if successful could I just leave a bulb pump system in place of lift pump? Do I actually need lift pump on such a small motor if bulb gets things done? Probably prone to perishing buy other than that?
Hopefully not a totally stupid question so apologies in advance, I just wondered if it would suffice or be kept as strictly plan b as and when...
 
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neil_s

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I modified the Lister 15hp diesel I had in an earlier boat by fitting a lift pump and relocating the fuel tank below the cockpit locker, but the motor worked perfectly well with simple gravity feed to the injector pump. With the fuel feed from the bottom of the tank, you won't need the bulb, either.
 
scozzy

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Update...tried bleeding system again just now, getting diesel to fuel filter,to bleed screw on front of engine but not getting to top injector.....its taken quite a while to do so thinking pumps about done...or do I have corrosion/blockage in feel pipe to injector? Anyone with similar tale of woe?
 
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spannerman

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Did you bleed it at the injector? Slacken the nut on the pipe at the injector and crank until fuel leaks out, tighten and it should start.
 
scozzy

scozzy

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spannerman said:
Did you bleed it at the injector? Slacken the nut on the pipe at the injector and crank until fuel leaks out, tighten and it should start.
Click to expand...
That's my current issue and concern with pump...ive bled up to the injector but no fuel reaching it?!....its an uphill journey so wondering if pump diaphram failing or just not up to job,other points quite a weak flow..May just put a bulb in line before lift pump to help,its ceamped in my engine bay and would be considerably easier than faff of replacing pump
 
Bilgediver

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Does your lift pump have a screw on the top of the dome? If the answer is yes then your lift pump may have a wee filter basket inside. Check if this is clear and not blocked. If blocked wash clean and replace and might be good to go.
 
VicS

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scozzy said:
That's my current issue and concern with pump...ive bled up to the injector but no fuel reaching it?!....its an uphill journey so wondering if pump diaphram failing or just not up to job,other points quite a weak flow..May just put a bulb in line before lift pump to help,its ceamped in my engine bay and would be considerably easier than faff of replacing pump
Click to expand...
If the pump performance is poor it is worth removing stripping down and cleaning the valves ( also examine the diaphragm, but a punctured diaphragm will result in diesel fuel getting into the lub oil sump). Details are in the workshop manual.
As far as i can tell there are no parts available for the pump so if it is knackered it must be replaced. (note that the pump for the 1GM10 is different to the pump for other GM engines)

The lift pump is necessary to deliver fuel to the injector pump. A bulb in the line from the tank is useful for priming and bleeding the system without cranking the engine but is not a substitute for the lift pump during operation of the engine( unless someone manually pumps it all the time).

The only alternative to a lift pump is an elevated "day tank" to feed fuel by gravity and which is filled manually .
 
scozzy

scozzy

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VicS said:
If the pump performance is poor it is worth removing stripping down and cleaning the valves ( also examine the diaphragm, but a punctured diaphragm will result in diesel fuel getting into the lub oil sump). Details are in the workshop manual.
As far as i can tell there are no parts available for the pump so if it is knackered it must be replaced. (note that the pump for the 1GM10 is different to the pump for other GM engines)

The lift pump is necessary to deliver fuel to the injector pump. A bulb in the line from the tank is useful for priming and bleeding the system without cranking the engine but is not a substitute for the lift pump during operation of the engine( unless someone manually pumps it all the time).

The only alternative to a lift pump is an elevated "day tank" to feed fuel by gravity and which is filled manually .
Click to expand...

Many thanks for this ,I'm just mentally preparing now for the gymnastics required to remove and inspect!
 
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