Mechanical Fuel Pump & Fuel Delivery Troubleshoot
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=38880
Printed Date: October-07-2024 at 8:33am
Topic: Mechanical Fuel Pump & Fuel Delivery Troubleshoot
Posted By: namart2001
Subject: Mechanical Fuel Pump & Fuel Delivery Troubleshoot
Date Posted: June-02-2016 at 9:44pm
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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. |
Replies:
Posted By: Bri892001
Date Posted: June-02-2016 at 11:14pm
| 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. |
Posted By: 8122pbrainard
Date Posted: June-03-2016 at 12:43am
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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. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: phatsat67
Date Posted: June-03-2016 at 10:09am
| 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. |
Posted By: namart2001
Date Posted: June-03-2016 at 11:04am
| Thanks, I'll do a little more checking and report back. |
Posted By: namart2001
Date Posted: June-06-2016 at 2:54pm
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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 |
Posted By: phatsat67
Date Posted: June-06-2016 at 3:29pm
| 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. |
Posted By: KENO
Date Posted: June-07-2016 at 9:21am
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 |
namart2001 wrote:Posted By: KENO
Date Posted: June-07-2016 at 9:37am
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http://www.uscgboating.org/assets/1/AssetManager/ABYC.1002.01.pdf" rel="nofollow - fuel systems In the link above is lots of good info on fuel lines among other things KenO |
Posted By: namart2001
Date Posted: June-08-2016 at 10:21pm
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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. 👍 |
Posted By: jschultz
Date Posted: July-11-2016 at 2:26pm
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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! ------------- Joe Schultz |
Posted By: Joby1969
Date Posted: July-11-2016 at 6:49pm
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that clear tube is just for pump failure,the gas goes into the carb and gets burnt off reducing a chance for a fire ------------- my 1980 SN is mad at my 2009 HD |