qd-20 conversion to fuel pump

[amuller]

Thanks for the report. Interesting. I’m still not entirely convinced but maybe I will get there.

[retiredoz]

I have a 305751. Send me an email or message thru here if you’re interested

[cc67]

What pump would you recommend for an 18 hp ?

[Steve D]

The small square one would work ok 388685, the other version 438562 would work great too and is easier to rebuild if need be. Some guys have purchased the small cheap ones on ebay for about $15 and I mostly hear about problems with those. You might get lucky, or you might get stranded. I’d stay away. You might have to bite the bullet on the price to get a good OEM fuel pump.

A good compromise, for me anyway, has been to buy the EMP brand (Engineered Marine Products). They’re priced about 1/2 way between OEM and Chineseum. I’ve bought 7 or 8 of their fuel pumps, and other outboard products, and they seem to be of good quality and haven’t had a problem with any of their stuff.

• This reply was modified 3 years, 9 months ago by Steve D.
• This reply was modified 3 years, 9 months ago by Steve D.

[cc67]

Looks like prices have gone up. Still not bad though. Where do you get the gasket for the engine mounting plate?

[need2fish]

Steve — can you tell us if you have any compression drop as a result of using the plate, and/or difference of color of top plug? (The latter may take some time to occur).

It stands to reason the charge for that cylinder will be shaped differently and may have lower density because some of the charge may have gone out through the exhaust ports. If there’s no way to measure it, the point is moot.

(if it makes no difference, why would the OMC engineers and the factory put so much expense into creating the deflectors).

I don’t have access to a milling machine, but it would be an interesting exercise to put a plate in both bypass ports. That’ll double the effect(s). Either way, measuring torque, top rpm, unburned fuel, fuel efficiency would be tough.

(insert lightbulb emoji here) . Take the bottom deflector out , turn it upside down and deflector out — just checking my Fastwin — it may fit

[Steve D]

I’m sure the engineers knew what they were doing and my short test of 1/2 hour run time only showed it seemed to have no ~immediate~ impact.

In the future when I re-install it on a motor, I think I’ll just use the plate over the original bypass cover, as was done with the plates Frank R. used to make, as mentioned in this post. Then you retain whatever function/benefit the deflector provides.

https://aomci.org/forums/topic/bypass-cover-for-a-johnson-ad-10/

[crosbyman]

I left the bypass cover on……. drilled a ..250 inch hole centered between the bypass cover and the aluminum plate …just behind the pump gasket and bolted everything up…. never had any issues

life is short … don’t worry to much about the internal turbulence

Joining AOMCI has priviledges 🙂

• This reply was modified 3 years, 8 months ago by crosbyman. Reason: to

[Steve D]

“life is short … don’t worry to much about the internal turbulence”

Are you speaking mechanically or philosophically? 🙂
Just kidding…so no fill in with epoxy on the bypass cover?

[crosbyman]

you can cut a gasket using the bypass cover as a guide and add 3/8 inches all around .. install it under the aluminum plate over the bypass cover……… bolt it all up………… and go fishing

Joining AOMCI has priviledges 🙂

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