MRD Fuel Injection

enzo

enzo

How's the waves?
Location
Bakersfield, California, United States
I could never get mine to run consistently. Even put foam in my tank to prevent bubbles in the fuel (per MRD). It is a very simple set up. But it just would not stay set. Jacked with it for a couple months than gave up.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Folks that have it and take the time to set it up right swear by it. Guzzles gas I hear.
Supposedly has a bad problem coming off high speed throttle chops.
Maybe I am wrong?
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Mile9c1 said:
Starvin' Marvin has tried a fuel injection system. I remember him talking about it but I don't know if it was MRD.
Click to expand...


I believe MRD was the only system ever successfully mass produced. Well, you know...mass produced for a ski, which I guess is still 5 handmade systems.:biggthumpup:
 
Prem1x

Prem1x

Tinkering obsessed
Location
Austin, TX
I've seen custom EFI systems back in the day.

My MRD runs great. I do not think it "guzzles" fuel compared to a modified venturi carb. That is, unless you constantly keep the throttle pinned while in the air (impeller unhooked). Since the FI doesn't respond to pressure changed like a carb, it keeps sqirting max fuel and loading up the engine. But, in general, in choppy water conditions, you will find a high fuel usage rate with MFI.

I actually prefer tuning it to tuning dual carburetors.

Fuel tank foam or even better a GroupK air-fuel separator in the fuel lines would cure any air bubbles in the fuel issue (which causes hesitations).
 
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Scott Kalisch

Scott Kalisch

X
Location
Myrtle Beach
Jeff Jacobs ran a pretty cool EFI set up, i heard he is bringing it back out very soon.

Theoretically is an EFI set up is used with a stand alone ignition and right mapping, you could use a wireless set up to tune from the beach.
 
W

waxhead

wannabe backflipper
Location
gold coast
Prem1x said:
I've seen custom EFI systems back in the day.

My MRD runs great. I do not think it "guzzles" fuel compared to a modified venturi carb. That is, unless you constantly keep the throttle pinned while in the air (impeller unhooked). Since the FI doesn't respond to pressure changed like a carb, it keeps sqirting max fuel and loading up the engine. But, in general, in choppy water conditions, you will find a high fuel usage rate with MFI.

I actually prefer tuning it to tuning dual carburetors.

Fuel tank foam or even better a GroupK air-fuel separator in the fuel lines would cure any air bubbles in the fuel issue (which causes hesitations).
Click to expand...
I was wondering about that as well
using a air fuel seperator with a lift pump to get it there
 
masterblaster

masterblaster

X-H2
i pmed a few of you guys in the thread about some issues im having with a motor I bought with this setup on it. Has anyone tryed the air fuel seperator with no tank foam? what would be a easy way to build something onto the mrd to raise just the prox up higher to help keep water out of the motor.
 
'Crockett

'Crockett

Freelance Smartass
masterblaster said:
i pmed a few of you guys in the thread about some issues im having with a motor I bought with this setup on it. Has anyone tryed the air fuel seperator with no tank foam? what would be a easy way to build something onto the mrd to raise just the prox up higher to help keep water out of the motor.
Click to expand...


Hey man,

I got your PM . . . glad to see you finally got that ski fired. As I mentioned in PM I have complete tuning and mounting instructions, I just need to find them. . . . . .


Here's a short course for right now:

On an MRD unit the fuel flows in a constant loop back to tank through the bypass orifice in the metering valve. There is always fuel, at pressure, waiting at the metering valve to be used at all times when the ski is running. Basically the throttle position causes the metering valve to divert fuel into the motor instead of continuing back to tank.

There are 4 basic adjustments to be made to tune the unit.

Injector size is first. . . . .
Fuel pressure is second . . . .
Adjustment to the heim link connecting the linkage to the metering valve . . .
Adjust Pop Off pressure . . . .



I'm going to assume this was a running unit prior to you getting it so . . . .

Injector size:

If I'm remembering right this is a 46mm unit not a 50 so it probably has about #35 injector nozzles in it, and again we'll assume it was already working, so what ever they are they're probably pretty close to correct.


Fuel pressure:

The fuel pressure is adjusted with the brass "T" valve mounted to the throttle body. The further closed you go the higher the fuel pressure is because you are restricting the flow on it's way back to the tank. So further open is gonna make it leaner and further closed is gonna make it Richer.

For starters I'd set it at about 1-1/4 turns from fully closed. Closed is always the reference point to know where the "T" valve is set at. If you have it set below 1/2 turns you will completely flood the motor with fuel. If it's too far open it will have a real bad lean bog.


Heim joint on linkage arm to metering valve:

Once you get it set up and running to where it's ridable you may want to dial in the metering valve for precise throttle response (this may already be set) this is done by loosening the jam nuts on the center link of the heim joint and making SMALL adjustments of no more than 1/8 of a turn at a time till you get good clean throttle response.These adjustments are made with the motor NOT running.

Pop Off:

Again, this was probably already set by the previous owner but I'll go over it anyway. There are two types of Pop off valves, the "in tank version" that mounts on the pop off return line in the bottom of the tank and an "In-line" version that mounts in the middle of the pop off return line. It's function is to relieve excess pressure that spikes when the motor free revs as the ski bounces out of the water and the prop unloads. Both styles can be adjusted to apply more or less spring pressure against the seat to raise and lower pressure. I believe we used to run ours at around 12 lbs. pop off pressure.


Several common problems to watch for:

Only use screen type filter to the fuel pump, some of the paper style filters and the sintered bronze one's will restrict the fuel flow and cause problems.

Make sure to remove the stock fuel tank check valve, because the fuel is constantly flowing back to tank it will cause the tank to build pressure which will over pressure the system and cause massive flooding of the engine.

Almost all the problems I have had with MRD's over the years I ran them were related to the two check valves in the system. The little o-rings get worn or cracked and no longer hold pressure properly. The o-rings can be replaced by disassembling the check valve (they are viton o-rings) or you can replace the entire check valve. I think I paid about $90.00 for 2 new check valves the last time I bought some. The other problem is that the check valves get debris in them from the fuel tank and stick open occasionally.


I'll dig around for those instructions to send you a copy, but please be patient, as I said in my PM all my stuff is still boxed up from my recent move.

'Crockett
 
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masterblaster

masterblaster

X-H2
thanks for the informative posts guys,im going to post some pics of this setup,not sure about the check valves and some of the fittings

fuel pump angle of t valve,set to 1 3/4 turn out
PB200061(Small).JPG


brass fitting maybe check valve coming off one of the return lines back to tank?

PB200062(Small).JPG


linkage setup,where is the other check valve in this pic?
PB200063(Small).JPG


the brass fitting connection just below the black plastic hoses on the y connection in this pic worries me,it feels lose but does not pull out,has no threads for a compression fitting on it?
PB200064(Small).JPG
 
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masterblaster

masterblaster

X-H2
messed with the fuel pump t valve today,im getting super sensitive throttle responce,if i pull the throttle to wide open it bogs then shuts off,with the t valve 1 3/4 turns out same thing when i take it a little more open as well?
 
masterblaster

masterblaster

X-H2
anyone know where to find the fuel pump real seal? be nice to know the mcmaster part # for it.
 
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