Carbed BB 502 with mechanical fuel pumps. Motors have on board merc fuel filter/water seps. Do I have to run the remote mounted racor fuel filters as well? Concerned that with two filters and the fuel monitors from navman I am restricting fuel too much.

Thoughts?

Thanks

If You Install A Racor 3120-rac-32 Just Make Sure You Use The Proper Fuel Line Size. Most Problems We See Is The System Is Not Plumbed Right.

I run Racors. I think they have higher flow than Merc. I wouldn't run both.

ditto what reddog said

Boat has four 75 gallon tanks burried low in the hull, hoses go up about 18-20 inches above the cockpit floor into a manifold system then down into engine bay racors and then into mechanical fuel pumps on motors. Having fuel delivery issues.

Planning on re-plumbing from tanks to racors - what size hose do you recommend?

Also - would you relocate fuel manifold down into engine bay to avoid the ups and downs?

Swamplizard, if you're the least bit concerned about debris in your fuel, use the RACOR. It has 10 micron filtration as compared to 70 microns for the standard Merc. I experienced a debris problem with 502EFI's and I installed an "additional" RACOR after my Merc filters. I had enough debris to clog the VST screen in one of my EFI's. The standard Merc filter catches most debris and the RACOR anything minute. For me the twin filters work great. I don't get the RACOR dirty too much as the Merc catches most debris, but the RACOR keeps the VST screen perfect. I have 300 hrs with the RACOR system now and no trace of VST screen problems. I change all filters @ 50 hrs typically.

Make sure there are no restrictions. Use as few elbows as you can. I see alot of 502's with a lean condition. Probably due to fuel restriction. You can't go wrong with having 1/2" fuel lines and making up custom pickups out of 1/2" copper tubing brazed/soldered into a 3/8 Npt barb Fitting that was drilled out to accept the tube. Did this on 38' Scarab when repowered to 572's from 330. Everything from the tank to the motor had to go. Because of the location of the pickup tube we were able to use straight fittings all the way to the pump. If you have to use elbows try 45's instead of 90's . I even took the die grinder to the fittings to smooth them out for better flow. Many elbows are basically cast and the path is a drilled out intersection. If you have to use them you can smooth them out and it will only cost some time. We used the big tall fram (truck style) filters, bolted to the bulkhead in front of the motors. Boat is shrink wrapped so I cant take any pics at this time. Hope this helps....BBB

Also Aeroquip makes a blue marine fuel hose that we used, it made the job a snap. BBB

thanks guys - I was doing a bit of research anf found that most on motor filters (quicksilver/mercs cant flow that much fuel...425 HP motors can burn 40-plus GPH - if the filter can only handle 25 - big bottleneck. Replumbing the entire thing this weekend and double checking size of pickup tubes and probably going racor only.

I run the Napa /Wix filters. I did a little research when I built my blower motors , Probably over kill and anal. but I know I don't have a fuel flow prob.

They have more flow capability's than most.

I have a different adapter than the merc stuff its a 1x14 thread.

Tere is some #'s to give ya an idea.
#3005 flows 15gpm has a 3 micron rating and also had a drain in it measures 7.3x3.6

#3604 flow 15gmp 8 microns 9.7x3.6 it bigger
3604xe has a 2 micron rating same flow

The XE series must have a different element inside for the smaller microns

For the fuel filter adapter base like Teague,Cp,Trick has a 1inch x 12 thread Teagues filter is a fram it was the worse.Trick uses the wix.dont remember on the CP

Part #'s
3418 flows 12-15GPM at 12 microns 8,419x3.698 about 8.00 at Napa Jobber

#3123 15gpm 12 micron measures 6.629 x3.698

they all are about the same dia . the length makes a differance in flow.

Napa Wix filter tech line 1800-949-6698

I ck with Teague and CP they rate theres at GPH Not GPM-Gallons Per Minute!!! So when they say it flows 140GPH it flows 2.33 gallons per minute


Hope this make ya think

Rob