fuel pumps

[jhjesse]

So I ordered a couple of Mikuni high volume fuel pumps a couple of months ago thinking I would install them this coming winter.
Well last weekend the Misses and I went out for a cruise up the lake onto the river and back. While we were coming back we ran into a bass tournament. Those guys are CRAZY!! I got off to the side and let about 30 boats by, then hammered the throttle to get out of their way. I stayed in the throttle all the way back to the dock.
After backing the trailer into the water, I went to load the boat and it was hard to start. (both engines) I popped the lid and the first thing I noticed was the fuel filters were bone dry. Rats!! Fuel pumps are giving up. Funny thing how both of them started to go at the same time.
So I have spent the last couple of evenings mounting and plumbing the new fuel pumps.
Man I cannot believe the difference. Less choking on cold start and the filters are full. I now have plenty of fuel and hot starts are a snap.
Wish I would have done this sooner.

 

[Guest_User]

awesome!:thumbsup:
it`s a beautiful thing isn`t it! :cheers:

 

[Sportster-2001-951C-Stock]

Those were crankcase pulse diaphragm pumps, right? Were they just too small, or were the valves tired?

Just wondering..... wasn't aware of some pumps not being large enough.

 

[jhjesse]

Those were crankcase pulse diaphragm pumps, right? Were they just too small, or were the valves tired?

Just wondering..... wasn't aware of some pumps not being large enough.

Yeah, the old pumps were just tired. I looked into OEM pumps, but they are hard to find. I don't think Mikuni makes them anymore.

 

[dbracela]

That looks fantastic. Any chance you'll do a write up on how you did it?

 

[jhjesse]

That looks fantastic. Any chance you'll do a write up on how you did it?

No problem. I will write something up in a couple days.

 

[jhjesse]

dbracela,
Here is how I did it. I apologize for some of the pics. I just didn't feel like disassembling just for pics.

Went to O'Reilly's Auto Parts and picked up 15' of ethanol safe 1/4" fuel hose and some 1/4" vacuum plugs. (new sales pitch...I guess)
Next was to decide where to mount the new Mikuni high volume fuel pumps.
I Could mount them in the same location as the old ones, but I would have to modify the old bracket, or fabricate a new one because the new pumps have a different bolt pattern, size and shape as the old pumps. Also in order to locate the new pumps where the old pumps are located would mean working in tight quarters, or removing the exhaust. Didn't really want to do either, so I decided to locate the new pumps on the wall housing the oil tank and ECM.


Holding each new pump up on the wall I determined they should be mounted directly above the fuel baffle for ease of installation, as well as access. I used #10 x 1 1/4" stainless screws along with stainless washers, because of the thickness of the fiberglass, as well as, pump thickness at the bolt holes. Any longer screws would protrude into the rear seat...not good.


I also mounted the new pumps so that the inlet ports were facing each other to make the connections to the fuel baffle directly below easy and neat.

 

[jhjesse]

The first connection to the new pumps was connecting the inlet ports to the fuel baffle with inline filters in between. (fram g3 filters)
Problem: If I connect right side pump to right side baffle port and left to left the 5/16" hose will have too much bend and I was concerned about kinking it and choking off the fuel flow.
Solution: Connect the right side baffle port to the left pump and vice versa making a nice long curve in the hose. Doesn't matter which side the fuel comes from because it all comes from the same place.


Next I removed the old pumps, hoses and pulse line. The pulse line was a bugger to get loose from the engine. It was almost as if someone used rubber weld or something. :facepalm::lol: I also temporarily removed the fuel return lines on top of the carbs to access the inlet ports. With everything now cleared out of the way I can run the new lines to each carb.
The new high volume pumps have two 1/4" outlet ports instead of the OEM 5/16" single port, therefore an additional line will be required. The new pump will now feed each carb individually instead of the mag carb feeding the pto carb.
First I ran the pulse line from the engine to the pulse port on the new pumps. Because the new pumps are mounted in opposite directions, the left pulse port is pointing down and the right port is pointing up. No big deal just had to cut a longer piece for the right side.
Next, I ran a line from the top outlet port of the new pumps to the mag carbs.
Problem: The mag carb inlet ports are 5/16" and not 1/4".
Solution: With little grease and some slight force the hose went on just fine.
Next was connecting the pto carbs to the remaining outlet ports on the new fuel pump. This was a no brainer because both the outlet and inlet ports are 1/4".

Edit: I used all stainless hose clamps to secure the hose connections. I think there are some stainless imitations out there...so if doing this or any fuel hose replacement, make sure the clamps are all stainless.

 

[Guest_User]

Nice write up and an alternative location.

but for you guys worrying about the OEM fuel pump bracket, easy peasy...

no need to remove the head pipe, just the bracket, use one existing hole and drill and tap for another. cake walk...lol...


note* to "worm" the 1/4 hose over the 5/16 carb inlet just warm up the hose be either using a Hot gun, or sticking the end of the hose in a very hot cup of water. just remember to blow off the water when installing.

this softens the hose and makes it much easier to slip over the larger fitting...

 

[jhjesse]

Now to address the remaining port on the mag carb which originally fed the pto carb.
Problem: Pale Rider used epoxy to fill the port up and seal it off on His fuel pump install. Love this idea, but it will require carb removal. I wanted to do something to seal the port off without removing the carb.
Solution: I mixed up some good marine epoxy and coated two #8 stainless screws with epoxy (one for each carb) and inserted into the port. I then put a light coat of epoxy where the screw head and the nipple meet and let it set for a few minutes.
Next I filled a 1/4" vacuum port plug with epoxy and installed it onto the carb port and used a hose clamp to seal. Then wiped up any excess epoxy.
I let everything set for 24hrs. then leaked tested. Thank goodness no leaks. Success!
The fuel filters were never more than 1/4 full, and now they are 3/4 full. Engine starts and runs great.
Hope this helps. Let me know what you think.

Pictures are from one of the old fuel pumps for demonstration purposes only:

 

[jhjesse]

Nice write up and an alternative location.

but for you guys worrying about the OEM fuel pump bracket, easy peasy...

no need to remove the head pipe, just the bracket, use one existing hole and drill and tap for another. cake walk...lol...


note* to "worm" the 1/4 hose over the 5/16 carb inlet just warm up the hose be either using a Hot gun, or sticking the end of the hose in a very hot cup of water. just remember to blow off the water when installing.

this softens the hose and makes it much easier to slip over the larger fitting...

Yep, worming the hose with a tiny amount of grease works wonders. :thumbsup:

 

[dbracela]

Excellent write up, and thanks for taking the time to do that. I think it looks great, and obviously works well. My fuel filters are always about 1/4 full, so I've been thinking its time to do something about it.

 

[jhjesse]

Excellent write up, and thanks for taking the time to do that. I think it looks great, and obviously works well. My fuel filters are always about 1/4 full, so I've been thinking its time to do something about it.

Where I bought mine:
http://www.watercraftsuperstore.net/714HP011.html

 

[jhjesse]

Update:
Out on the lake and after about an hour the left engine started losing rpms and would not run above 4000rpms. Got the boat home and started diagnosing the problem.
This is what I found.


These Fram g3 filters are brand new. Seems as though the new high volume Mikuni fuel pumps were collapsing them. I replaced them with all metal filters. and hopefully that solves the problem.

Lesson learned: When installing new Mikuni high volume fuel pumps, use metal filters.

 

[Guest_User]

Update:
Out on the lake and after about an hour the left engine started losing rpms and would not run above 4000rpms. Got the boat home and started diagnosing the problem.
This is what I found.
View attachment 21382View attachment 21383

These Fram g3 filters are brand new. Seems as though the new high volume Mikuni fuel pumps were collapsing them. I replaced them with all metal filters. and hopefully that solves the problem.

Lesson learned: When installing new Mikuni high volume fuel pumps, use metal filters.

Hey Jesse, what`s up brotha!

I`m not a big fan of any plastic filter yet alone a plastic filter in the engine compartment regardless of others opinions.
I did however run Hastings metal housing filters last year without issue. I didn`t mind not being able to visually see the fuel in the filter, that is never a correct indication of flow anyways.
I do like the Racor 120`s with spin on cartridge, although a bit overkill, our boats are boats are boats and running a water separator/fuel filter is never a bad thing. I did inquire wether the Mikuni pumps could pull fuel thru the cartridges and these have been used on many many yamaha jet boats by my friends shop for years without failure.

so, if your going to keep you boat for a few more years the Racor`s couldn`t hurt... I know they are pricey and you could get 100 regular filters for the same cost. I just get that warm and fuzzy feeling knowing they are also water separators with todays fuels and not knowing these marine or gas stations any more these days... especially since after a good whopping storm...

Good catch !

 

[jhjesse]

Andy,
Good to hear from ya! The Fram G3 filters were the filters on the boat before, so I didn't see any problem just going back with them. Little did I know that plastic filters are not a good thing for high volume fuel pumps. :facepalm:
I am like you, I don't need to see fuel going through the filter because I change them regularly along with all other maintenance items.
The Racor's are a bit too much for my taste, but they are really cool. Probably use them on my next boat.

Have a good one and get out on the water already!! LOL

 

[Guest_User]

Andy,
Good to hear from ya! The Fram G3 filters were the filters on the boat before, so I didn't see any problem just going back with them. Little did I know that plastic filters are not a good thing for high volume fuel pumps. :facepalm:
I am like you, I don't need to see fuel going through the filter because I change them regularly along with all other maintenance items.
The Racor's are a bit too much for my taste, but they are really cool. Probably use them on my next boat.

Have a good one and get out on the water already!! LOL

hahha I wish I could go right now, the boat is ready... been busy reading up on the DMV stuff... NJ seems simple compared to what you have to go thru here, wow!!!
these crazy NC registration and license rules are killing me... argh :facepalm:

 

[Coastiejoe]

hahha I wish I could go right now, the boat is ready... been busy reading up on the DMV stuff... NJ seems simple compared to what you have to go thru here, wow!!!
these crazy NC registration and license rules are killing me... argh :facepalm:

Ohio is pretty simple as well. But like you said, some states are unreal in what is required and what it costs,,

 

[Guest_User]

Ohio is pretty simple as well. But like you said, some states are unreal in what is required and what it costs,,

Off Topic alert:
there are leveled tiers for young drivers I think starting with 15, really, 15, and all`s they need to carry is liability to drive...
get hit by one of these youngin`s and your done...

in NC and out of state new resident:
written test, visions test, 2 sign tests, and the road test if deemed necc by the instructor,,, really...
and then there is a different agency just for the boat, and you can not do it all under one roof, you have to hop all over town to these different places... and have the truck inspected even tho my inspection sticker says it`s good for another 3 years... argh...

 

[Albysure]

Just helped my friend out with his boat in doing this mod....but when I was out getting parts for it I seen a Y fitting for gas lines... So instead of JB weld I put in two 6 inch lines on the out ports and ran them to this Y fitting...working good as of now....any issues you guys think about running it this way ?

Thanks

 

[jhjesse]

Just helped my friend out with his boat in doing this mod....but when I was out getting parts for it I seen a Y fitting for gas lines... So instead of JB weld I put in two 6 inch lines on the out ports and ran them to this Y fitting...working good as of now....any issues you guys think about running it this way ?

Thanks

Can't picture it in my simple mind. If you can post a pic. I would also say if it is running good then, it is probably OK.

 

[Guest_User]

the main purpose for the blocking of unused ports properly is to lessen the amount of fuel line or clamps to prevent the number of possible leaks...

 

[USAF_Pride]

What was the part number of the pump you bought (for future reference)?

Nice write up. I think this will be on my list!!

 

[jhjesse]

What was the part number of the pump you bought (for future reference)?

Check out post #13 for web site.

 

[Sportster-2001-951C-Stock]

Yes, coast guard approved A1 hose, brass or stainless fittings and fuel proof sealants should be used, especially below deck. JB Weld and/or silicone will eventually dissolve with constant exposure to fuel, try to find something else such as an unthreaded rod that properly fits in the fuel line hose, Permatex #3D, or loctite 504 are fuel proof sealants. You may find other products which are designed for the purpose but unless specifically rated for fuel, don't just choose anything (such as JB Weld) and slap it on there.