Fast Fred's OMC Mod 50 secrets Thread #2

[Powerabout]

Get a flow gauge and valve and draw 12gph off in place of the carbs so you know what pressure you will have at WOT before you run the motor.
Thats what I used to do to ensure you had pressure before you actually ran the boat.

On crankcase fuel pumps I used the shop vacuum source ( for draining engine oil) with a flow gauge and a vacuum gauge and pulled the flow and checked for the vacuum reading and or used the sensor that was on V6 engines in the 80's
I used the flow rate of 10% of horsepower is US GPH.

( test hard ..race easy)

[Tim Kurcz]

Hey Fred, you're correct to keep restricting the jet until 3-1/2 psi is reached. The Powerabout suggestion to voulme check into into a fuel can is a good one as well. So, at 12 GPH you should have a gallon in 5 minutes. More critical is you install a pressure guage where you can see it at max RPM and confirm you have pressure underway. Once confirmed, you can remove the guage. Good luck!

Tim

[Fast Fred]

ok , i did some tests, put a .029 restrictor jet in psi came up to 3 1/2 psi, reg was maxed out
flow was weak, so i ripped that reg off, and went to a Holly 1to5psi reg, put in a .056 restrictor jet. the pressure came right up to 3 1/2 psi with in like 3 or 4 turns on the reg.
so with the moda not runnin at 3 1/2 psi on the fuel rail how much return to the tank should i get? or about how long to fill a gal from the return? thanks guys seems i'm allmost there

[Tim Kurcz]

Hi Fred, You should have 12 gallons per hour = 1 gallon per 5 minutes. Sounds like you had a defective click-stop regulator. Just had the same thing with a new installation! Perhaps Mr. Gasket is having the regs made in China????

Be sure to guage and observe pressure at WOT at least once! Good luck!

Tim

[Fast Fred]

i tried two of them style regs they were Specktra or some thing like that, they looked just like the Mr. Gasket one. goin to leave the gauge on the boat, be lookin at it from time to time thanks again.

[Fast Fred]

she flowed 121-122 oz in 5 mins,or 11.25 gals per hr., thinkin up the restrictor jet size(56d in there now) then resquese the psi back up to 3 1/2psi and re test the flow rate. sound right? thanks

[Tim Kurcz]

Hey Fred, You're close enough for a lake trial. Remember the engine is feeding upstream of the restrictor, and that your pump has 32 GPH capacity. Just keep an eye on your pressure at WOT to make sure delivery doesn't drop. Tim

[Fast Fred]

i never make out well at the lakes around hear, the cops just show up, some times before i get off the trailer, headed for the bay goin to use a .060C jet i found in my pile. then make that 5min flow test again.

[Tim Kurcz]

Bummer about the cops, Fred. Had the same problem here until I built a quiet mid. Suggest while you're testing, take out the restrictor and test free flow at 5 minutes to get a baseline through your fuel system for comparison. Should be about 2.5 gallons.

[Fast Fred]

?, took her out, she washed out my plugs, ?, thinkin my floats moved and or the level is to high. carbs seem too wet, takin them off, lookin them over, try again.