300 Johnson 4L V8

[jd98x]

I just bought a 1990 300 Johnson 4L V8 and it has two VROs on it, im gonna pull them off and mix the fuel and use a fuel pump. My questions are what fuel pump should i run, what mixture should i run, what oil should i use and how much fuel pressure should i be running? Any info would help, thanx..

[mrv8outboard]

Is it Stock? I raced mine pre mixed and used the VRO's with the oil side plugged. I used 1/2" fuel line all the way to the transom area to the OEM primer pump then 3/8" to the engines. I have run this on all three of my race boats.
But others will say I am nut's, no power head failures to date knock on wood.

[Riverratt]

I am running an unregulated Holley Red pump mixed at 50:1 with Evinrude XD25 or XD30. Don't forget to plug the pulse fittings.

[STV_Keith]

I run a Holley Red with the internal regulator spring stretched just a bit. 5-6psi fuel pressure. 40:1 with Merc Premium Plus.

[jd98x]

do you mount the holley pump on the motor or the transom? i have a pump on the transom already, its a carter pump? im not sure what that pump is.

[Riverratt]

Inside the boat. Carter makes a good pump also.

[wideglide55]

Check your lower oil often,they like to eat cases and gears if they are not pinned and ran on the surface

[jd98x]

thanks for all the help, im tryin to learn as much about these things as i can so i dont burn this bad chicken down the first time i put the boots to it!!

[STV_Keith]

On the transom...

http://www.speedcraving.com/scarab/Upgrades08/stb-transom02.jpg

[JrCRXHF]

Holley pump with external fuel pressure regulator i set mine at around 6.5psi. 50:1 with penz full syn. Might run omc oil next summer i don't know yet.

I still have the pulse on the side of block running up to the carbs.

[jd98x]

im tryin to find parts to change this to a 20inch mid, need a housing and driveshaft if anyone knows of any.

[jenksam]

:cheers:I HAVE PLENTY OF THEM JUST LET ME KNOW WHAT YOU NEED.

[VELOCITY 3.6GT]

Try hanafords marine in new windsor new york. He bought my 3.6 gt when it threw a cylinder. It had a 20 inch shaft, low water pickup and the oil was always changed often and it was super clean. He bought it for parts when he bought my fathers 32 baja that had twins on it. Not sure if he would part it out, but it does not hurt to ask. His name is rick. 845-561-2771

[jerry1865]

i have an 88 4.0l . i had quite a bit of trouble with the fuel system.
i run the holley red pump, the holley regulator will allow pressure to creep up slowly.(so it had to go) and i have a long idle time in and out of the river.
what i did to cure the problem: i made my own in-line regulator and put it in a return line . that way the fuel pressure is guanteed to never get over 5.5 psi. at or below 5.5 the return line is completely closed. but anthing over that and the regulator opens and lets the excess go back into the tank(s)

and yes , i did some tail chasing before i figured that out,lol

[JrCRXHF]

This is a good idea i am getting a electric fuel pressure gauge to see how mine is running.

With my fuel injected cars we always run return to the tank. I did not like the dead end system but alot of carb motors run setups like this so i did not really think anything of it.


But good information.

[jerry1865]

ditto; with all my other motors and even the ones i went thru for others i never had anywhere near the issues with the fuel system as i have had with this one.

i wouldnt trade the any of the high dollar systems for my home-made regulator and return line. it solved a month long night-mare for me.
the regulator is nothing more than a check valve with a matched spring. the more pressue behind the spring = more psi before it opens.
i believe it will make the fuel pump last longer between kits as well, the relief in the pump never has to open.
jerry

[JrCRXHF]

This is the style that you need. I also have 2 fuel ports on my fuel tank because my boat use to have twin motors.

http://www.dnamotoring.com/formulajdm/images/fpr/9002_RED_DSM-FPR.jpg

If you look up dsm fuel pressure regulator