Help Identifying Cause of Low Fuel Pressure |
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MrMcD ![]() Grand Poobah ![]() ![]() Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3734 |
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My buddy is a pretty fair mechanic, he brought his boat over to find out why it is so rich at idle and had no power above 2,800 RPM. His is a Chevy 350 but he had two wire switched in the fire order. He paid a shop to look at it and they claimed his coil wire was loose and they tightened that and told him it was fixed. His Chevy fire order is 18436572, he had wires 3 and 6 switched. The two were close enough that it ran but ran badly one of his plugs was fouled black but the other actually looked pretty good after running wired wrong.
This was after he installed a new Carb and a new distributor trying to fix his issue.
With two of us we could trace the wires really quickly and found the issue in 5 minutes. It can happen. Another possibility, the 351W and the early 302 do not use the same fire order so make sure you have the correct firing order for your specific 351W which is the same as the later 302 HO engines. The distributor will rotate Counter Clockwise and the order should be 1 3 7 2 6 5 4 8 Sometimes the simple things get us hung up on a repair. Cylinders 1234 are on the Driver side of the boat, cylinders 5678 are on the passenger side on your Ford V8 providing your engine is mounted with the water pump facing the front of the boat. FYI: I ran a 351w in my 78 Nautique with a burned valve for most of one summer. There was a piece of pie burned out of the exhaust valve and that boat ran pretty well, kept fouling the plug but when the plug was fresh you could hardly notice the bad cylinder. We were sking hard and barefooting so power was still pretty good. I don't think compression is your issue at this point.
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JayG80 ![]() Senior Member ![]() Joined: January-07-2007 Location: United States Status: Offline Points: 170 |
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Removing the muffler would be down on my list after “exhausting” all options and shooting my dog.
Preliminarily, remove the stern floorboard and inspect the muffler as boat runs. Pay attention to sounds and watch muffler while accelerating engine. My muffler sounded “funny” and pillowed up. I’m no expert, just a shade tree mechanic suggesting a remote cause based on my case/solution. |
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2007 Ski
2002 Ski |
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11018 |
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Umm.............I do like your answer, but you left out some important info............what kind of dog is it?
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dshack ![]() Groupie ![]() Joined: June-11-2021 Location: Utah Status: Offline Points: 47 |
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^ Duly noted!! My dogs are safe for now haha.
I might be onto something now, I started having an intermittent no start normal crank after running the engine for a bit. When it did it last night I checked and I'm not getting any spark. I pulled a code 14 for the PIP sensor. Going to just replace the whole distributor and see if that does anything. Hopefully this is all related to the core issue of lack of power and not just another thing to distract me! |
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Gary S ![]() Grand Poobah ![]() ![]() Joined: November-30-2006 Location: Illinois Status: Offline Points: 14096 |
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Seems lately that the most common fix to GT40 running problems is the PIP sensor. I have had the crank shaft position sensor,which is basically the same thing go out on every Jeep I have owned......
Make sure you order the correct one (cast gear) for a flat tappet engine.
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dshack ![]() Groupie ![]() Joined: June-11-2021 Location: Utah Status: Offline Points: 47 |
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Just pulled the distributor and turned it upside down and a little plastic chunk and spade connector fell out. Hopefully this is the smoking gun.
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11018 |
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For a replacement, Spectra FD-14 has been a good CCF choice over the years.
It has the cast iron gear and you can use your new cap or fill the vent hole with silicone.
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dshack ![]() Groupie ![]() Joined: June-11-2021 Location: Utah Status: Offline Points: 47 |
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I replaced the distributor and the engine sounded great in my driveway so I went out for a lake test with my 2.5 year old (her first time in a boat!). I will never forget the feeling of that first hole shot and the smile on my daughters face afterwards!! The boat ran great, cruised in the low 40s per my GPS watch with an unknown prop. Tons of low end power. Finally sounds like a boat should sound!
Only issue I had was the 15a fuel pump breaker tripped a few times. I would normally suspect a fuel pump going bad, but both are brand new. I think it is a bad breaker because it took a couple minutes to be able to reset it even with the ground pulled from the battery (it would immediately pop out after I pushed it in). Any idea on generic part numbers for the breaker at a parts store? Or is this something I'll need to order from nautiqueparts? |
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11018 |
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Don't know if you're one of those Amazon types, but here's a link and it tells what the breakers are called if you want to shop around ![]() Not a lot of price difference wherever you look, shipping is a different story though. Maybe with all the work on the boat, you have a chafed wire, but putting a new breaker in will tell you a lot, like whether the breaker is bad or you have another problem. And............good job, you work fast It's never good when pieces parts fall out of the distributor
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8122pbrainard ![]() Grand Poobah ![]() ![]() Joined: September-14-2006 Location: Three Lakes Wi. Status: Offline Points: 41045 |
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David, I'd say the breaker needed to cool to reset it. Regarding the potential overload, you may what to test to see if the breaker is bad or just doing it's job. ![]() You sure made great progress.
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KENO ![]() Grand Poobah ![]() Joined: June-06-2004 Location: United States Status: Offline Points: 11018 |
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It's probably worth mentioning that the breaker supplies the fuel pump relay too along with the fuel pumps if you're looking for possible "culprits".
It sounds like you have new relays, but ya never know
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MrMcD ![]() Grand Poobah ![]() ![]() Joined: January-28-2014 Location: Folsom, CA Status: Offline Points: 3734 |
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Nice work chasing the problem down. Glad you finally got to feel the power! Your going downhill now.
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