2001 21V Riders Edition Fuel Pump or Oil Pressure Switch

[TeamAllen]

...I had my wife turn the key to the on position and I could hear the fuel pump prime for about 2 or 3 seconds. So I thought what the hell let me try and start the boat. It started right up without any hesitation...

Was the boat in the water or did you have the water running to your engine when you started the engine?

[Goofyr44]

For the test I had the boat in the drive way with a fake a lake. Does it make a difference with the boat in the water?


Sent from my iPhone using Tapatalk

[TeamAllen]

No, just wanted to make sure you had water getting to the impeller. I couldn't find any photos yet.
This youtube video gives you an idea od what it looks like.
https://www.youtube.com/watch?v=OyR8iPkIoQo

[Goofyr44]

Ok cool I ll check it out. Is the low pressure pump before or after the main fuel pump?


Sent from my iPhone using Tapatalk

[TeamAllen]

Before. It goes in between the tank and pump being closest to the tank as is feasible.

[Goofyr44]

Before. It goes in between the tank and pump being closest to the tank as is feasible.

Ok cool. That’s what I saw and figured. So basically the low pressure fuel pump will pump through the high pressure when vapor lock is present right?


Sent from my iPhone using Tapatalk

[TeamAllen]

I look at it as the new pump will push the the fuel to the existing pump then the exiting pump will push it the rest of the way. Before the existing pump would have to suck it up from the tank through the hot engine compartment and lines. That's where it would vaporize?
I am no expert at this, but that's how I understand it. It definitely works. My understanding is that is why the pumps are in the tanks now.

[Goofyr44]

Yeah that’s kinda what I figured. I guess if the main fuel pump ever goes out it may be a good option just to relocate the high pressure to the tank.


Sent from my iPhone using Tapatalk

[Goofyr44]

Hey, I have your same boat 1999 Tige 2100 V Riders Edition and went through a similar fiasco. It has 800 hours on the original mercruiser MPI 350 mag. Bought the boat in 2018 and every single one of my issues has been "fuel" related.

My best advice to you is to get a fuel pressure gauge and hook that up to the rail so you can see what the fuel pressure is at all times. With that connected, you can see what the fuel pressure is when you turn the key (which sends fuel to the fuel pump) and also when the engine is running. Check the manuals to see what the fuel pressure should be at all times. The fuel pressure should hold and not drop lower than 1 or 2 psi.

I had to replace the original fuel pump based on what i saw from these readings. I also had to replace the fuel pressure regulator. Also had a bunch of crap in my fuel tank (that accumulated over the years). I also found some pretty cheap Chinese fuel injectors on ebay/amazon and replaced all 8 of those which made a big difference for me as well.

Hope this helps.

John

Just curious how much of a PIA was changing the fuel pump. I think, praying not, that the fuel pump might be going out. I’m dreading changing it because the location is terrible.


Sent from my iPhone using Tapatalk

[mdk681]

I used to fight with something similar. I would get the boat up to temp, shut it down for a bit, followed by some hesitation/struggles starting again. I heard it was due to vapor lock - hot engine compartment on a hot day would make it worse. It seemed to go away when I replaced my blower fan with a bigger one and started leaving it on from the moment I set foot on the boat to the time it was back on the lift parked. Perhaps pulling in more fresh air and getting more of the hot air out helped.

I also had my boat die a couple seasons ago when surfing, it would crank no problem, but it wouldn't even sputter, just cranking with nothing else happening. When my mechanic checked it out on land, he said he had no issues starting it up. We were puzzled as he for sure thought it was the fuel pump. To be safe, I had him install a new fuel pump. I will say that he is a good friend of mine, and said he was cursing me out the entire time changing the pump, lol! Access is partially blocked by the shape of the hull, plus there was some annoying plastic cover hiding everything. He ended up getting the job done but the intermittent starting issue was still there. He then checked the cap/rotor, cleaned everything, and said he replaced some ignition switch (I think? sorry for my lack of mechanical knowledge) and that did the trick.