Mechanical Fuel Pump & Fuel Delivery Troubleshoot |
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Joby1969
Senior Member Joined: July-06-2015 Location: Conway Status: Offline Points: 160 |
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Posted: July-11-2016 at 6:49pm |
that clear tube is just for pump failure,the gas goes into the carb and gets burnt off reducing a chance for a fire
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my 1980 SN is mad at my 2009 HD
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jschultz
Newbie Joined: June-06-2010 Location: Illinois Status: Offline Points: 4 |
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I just fixed mine with just replacing the fuel pump. A valve inside it was frozen up with deposits but the rubber seals are cracked and dried out. I had noticed gas in the oil after the pump breather tube, the clear one was pumping gas! This is definitely a problem and I hope someone else sees this a saves them a trip to the dealer. It is not too difficult to replace the pump. In my case I had to replace the oil which was already fresh just before I started the engine again. My problem is definitely solved from an engine which seemed to be running to rich and could not be adjusted to idle properly. Watch that clear tube, it is a sign of failure if gas is going up it!
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Joe Schultz
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namart2001
Newbie Joined: March-16-2014 Location: United States Status: Offline Points: 21 |
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That's definitely some good info. I still need to get some new fuel lines ordered, but I'm back up and running with the new fuel pump. Got to love when you diagnose it right the first time, certainly doesn't always work that way-- least not for me.
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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KENO
Grand Poobah Joined: June-06-2004 Location: United States Status: Offline Points: 11061 |
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That's automotive non USCG approved. The USCG stuff would say USCG A1-15 or B1-15. A1-15 can be used on the pump suction or discharge, B1-15 only on the suction. KenO |
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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Does it state it's USCG approved ? If not I would just order from a marine supplier. 15 feet should get the job done but keeping extra is never a bad idea. Also, pick up some screw mount zip ties to re fix the fuel line to the stringer. While you're at it pull the inspect and clean the anti siphon valve.
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namart2001
Newbie Joined: March-16-2014 Location: United States Status: Offline Points: 21 |
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Did some testing over the weekend. The pump didn't pull any fuel out of a remote tank with a new, short fuel line, so I ordered a new pump. Although I don't think I have any fuel line issues at the moment, the main line is showing some signs of its age, will this work for a replacement:
HBD Thermoid NBR/PVC SAE30R6 Fuel Line Hose, 3/8" x 25' Length, 0.375" ID, Black https://www.amazon.com/dp/B00PLKV6C0/ref=cm_sw_r_cp_api_BLAvxbFQT4B2B |
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namart2001
Newbie Joined: March-16-2014 Location: United States Status: Offline Points: 21 |
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Thanks, I'll do a little more checking and report back.
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phatsat67
Grand Poobah Joined: March-13-2006 Location: Indiana Status: Offline Points: 6157 |
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Sounds like the fuel pump to me. You've already gotten further with most fuel diag than most can. Also, if there is an air leak pre pump could be another cause.
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8122pbrainard
Grand Poobah Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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nate,
Regarding the bench testing, all I've ever done after rebuilding a mechanical pump is put my finger over the in and out ports. Activating the lever arm, you should get suction on one and pressure on the other. |
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Bri892001
Grand Poobah Joined: September-27-2008 Location: Boston MA Status: Offline Points: 4947 |
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You could try some fresh rubber fuel line on the suction side, going into a portable tank, just to rule out tank or filter issues.
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namart2001
Newbie Joined: March-16-2014 Location: United States Status: Offline Points: 21 |
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I recently completed a rebuild on my carb (1984 SN2001 w/ 351w). Boat ran great on the trailer and then great for a few minutes on the water before it sputtered and died.
At home, I checked to make sure I'm still getting spark, which I am. I pulled the fuel line of the carb and it was bone dry so I pulled the main line off of the output of the fuel pump (mechanical) and cranked the engine for a little bit and got nothing. I pulled the fuel filter/water separator and it did not appear plugged. Because I actually had a filter on hand (this was on my to do list anyway), I went ahead and replaced it. I also stuck a baster down the main fuel line and was able to easily suck some fuel into the baster, so I do not believe I have blockage. I also pulled apart the fuel pump (thinking I'd see damage to the diaphragm) and found no visible damage. My questions are: 1) whether there's a good way to bench test the fuel pump; and 2) since the fuel filter looked clean and I'm able to siphon gas from the tank, should I just go ahead and order a new fuel pump? Side note, I added the info about the carb rebuild because I'm not totally ruling it out as a problem, but I think (and am somewhat hopeful) this was just a terribly ironic/timed fuel pump failure. |
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