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Dec 30th, 2023
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 Loss of fuel pressure
#13216569
07/16/19 06:32 PM
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Joined: Mar 2018
Posts: 44
basscatmo
OP
Outdoorsman
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OP
Outdoorsman
Joined: Mar 2018
Posts: 44 |
2018 Merc Pro XS 250 loses fuel pressure when idling and stops/won't start until I prime the bulb. After it gets some fuel, runs ok. Seems to run fine when on plane. Any ideas?
Thanks
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Re: Loss of fuel pressure
[Re: basscatmo]
#13216606
07/16/19 07:15 PM
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Joined: Sep 2003
Posts: 5,518
Bruce's
TFF Celebrity
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TFF Celebrity
Joined: Sep 2003
Posts: 5,518 |
Mine does the same thing. It does not like to idle long ways. It will do the same thing unless i idle it up faster.
Bruce's Sprinkler Repair
817-798-7246
52 years experience
State Licensed Irrigation
LI0017483
Fishing Texas lakes one at a time
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Re: Loss of fuel pressure
[Re: basscatmo]
#13218627
07/18/19 05:39 PM
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Joined: Apr 2014
Posts: 198
Fishcharmer
Outdoorsman
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Outdoorsman
Joined: Apr 2014
Posts: 198 |
I have seen a bad primer bulb be the cause of the same problem several times.... Replaced the bulb and that fixed it..
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Re: Loss of fuel pressure
[Re: basscatmo]
#13219494
07/19/19 03:23 PM
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Joined: Apr 2011
Posts: 1,526
DFW-fisherman
Extreme Angler
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Extreme Angler
Joined: Apr 2011
Posts: 1,526 |
Most primer bulbs have an internal check valve inside - sounds like it could be leaking allowing fuel pressure at the engine to flow back to the tank. Or, it could be the one at the fuel pickup line at the tank that is leaking back; I would check them both.
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Re: Loss of fuel pressure
[Re: basscatmo]
#13219610
07/19/19 05:14 PM
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Joined: Nov 2002
Posts: 4,439
Gamblinman
TFF Team Angler
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TFF Team Angler
Joined: Nov 2002
Posts: 4,439 |
Make sure fuel lines and primer bulb are made of the newer ethanol resistant materials. If you haven't, change all fuel lines and primer bulb from tank to engine.
Check screen in top of VST to make sure its not plugged with trash.
May be time to rebuild low pressure pulse pump. Fairly easy to do...just make sure you get the valves and springs in the correct position.
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Re: Loss of fuel pressure
[Re: basscatmo]
#13224267
07/24/19 04:06 PM
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Joined: Jun 2004
Posts: 1,509
OPTI
Extreme Angler
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Extreme Angler
Joined: Jun 2004
Posts: 1,509 |
The low pressure fuel pump is the problem the optimax uses a vacuum operated fuel pump and with the new style pressured fuel tank system the fuel demand valve will cause the fuel pump to work harder and stretch the diaphragms or tulip the mylar check valves. How I solved this problem was to replace the fuel demand valve and rebuild fuel pump. I got Mercury to pay for a few fuel pump but the technician needs to call Mercury and explain the situation but to be honest they may or may cover it. Had this problem quit a few times. boat builder covers the valve and Mercury the pump........OPTI
Last edited by OPTI; 07/24/19 04:07 PM.
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Re: Loss of fuel pressure
[Re: basscatmo]
#13225126
07/25/19 01:08 PM
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Joined: May 2003
Posts: 11,586
gary purdy
TFF Guru
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TFF Guru
Joined: May 2003
Posts: 11,586 |
Have seen lots of problems with the fuel demand valve.
The world will not be destroyed by those who do evil, but by those who watch them without doing anything. Remember what He has done and remember that He is not done yet!-- GOD IS GOOD
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