496/Raylar HO600 fuel questions
 

Good evening from the UK, I hope you are all well.

I bought a Donzi 26 with a Raylar HO600 engine (OW317280) last year and I have a few questions if anyone can help.

Ater the boat runs out of fuel is it normal for the whole fuel system to need stripping down and priming up to the fuel rail? I have a Racor pre filter that we filled with fuel to help but the cool fuel filter and pump chambers on the engine also had to be filled with fuel before it would start. We primed several times with the key without starting but this didnt help so are they not strong enough to self prime or do I maybe have a failing pump? Hose runs uphill from tank to racor pre filter around 2ft total length then 1ft downhill from filter to cool fuel on engine. Racor and cool fuel filter and screen filter are brand new, no evidence of any flaking paint inside them.

Also what should the fuel pressure be on the Raylar HO600 engine at the fuel rail? My mechanic has struggled to get hold of anyone at Raylar to ask, I had an Oring blow out of one of the round connectors on the crossover pipe, although this wasnt disturbed in the previous issue with the priming. Im worried the pressure may be set too high as the engine is running rich and we cant see why as there are no faults when scanned.

Thanks for any help.

That's totally normal once you run out of fuel. Your should be as far as I know 3-4 psi over stock. So 46-47 psi key on engine not running.

Ok thats a big help, thanks. I should be back down there this week so will see what its running.

You might need to prime the system but I find it hard to believe. If it doesnt stay primed and ready, that's another issue, air is getting in somewhere.

Do you have the stock regulator? You should be 1-2 PSI over stock. 43-44 PSI You really need to get an O2 sensor even after you are at 42-43 PSI. At that point you can run the boat, However, you really should ditch the stock regulator and put in an Aeromotive, They are more consistent and more accurate. You can take your fuel rail off and weld on a AN fitting, replace and plumb in the new regulator. It is 10 times more reliable for $150.000

Do you have the stock ECU program? Whos program is on the ECU? Raylar or Whipple? Stage 1, 2 or 3?

Unsure if I have a stock regulator in the cool fuel, the engine was bought by one of the previous owners of the boat from Raylar as a complete engine before they stopped doing them and just sold the kits.

As for the ECU Im pretty sure it is the correct Raylar HO600 going by an additional sticker on it that has almost faded. When it was scanned we found it was programmed by Whipple which seems to confirm it is not the stock program.

I like the sound of the more simple regulator and return line setup and will look at that if I cant get the current system right.

Thanks for the replies.

Here was the way we did it on mine. Simple.

Supposedly the Raylar program is slightly more conservative. Not knowing if it was a Whipple Stage 2 or 3 makes it a little difficult. Whipple did have specific programs for the Raylar 600 engine. What I can tell you is that even only 1.5 to 2 PSI over stock was very rich. The problem is that it varies greatly through the RPM range. For example, mine is spot on 12.8 AF at 5200, 5400 5600 but is rich idle through about 3000. Yes, this can be fixed but it took a month of fooling around to get it here. The program can be tweaked but the best way to figure any of it out is to just get an O2 sensor and be done.

Thats a neat install and some great information thanks. Sounds like a lot to look into but I dont mind spending the time to figure it out. Il look into the O2 sensor but my headers arent set up for them yet. Il chat to the mechanic this week.

I was under the impression the stock merc cool fuel setup was not up to the task of feeding the HO600? I've seen it recommended by Raylar to eliminate the merc setup and go Aeromotive and return to tank like Keith has done.

When checking your fuel pressures engine running make sure to have the rubber vaccumn hose unhooked from the regulator.

Another reason for fuel pressure bleed down is a stuck open and or injector(s) the pintle can not fully seat close.

Or a fuel pump check valve issue

Thanks BUP. Added to the list for the mechanic to check .

Ok so a month has gone by and Ive had very little time to sort the boat. Mechanics findings were that the fuel pressure is all over the place, sometimes as low as 35psi, sometime shoots over 70psi, probably lucky the engine is still in one piece. Apparently the regulator in the cool fuel module isnt a standard part. Hes messed about for hours and Ive ran up a massive labour bill, and got nowhere...

So have done some research into an external pump and return line system to hopefully solve these issues and simplify things in future. Availability of the parts in the UK is quite important. Can get some Aeromotive parts here and there, no Weldon parts anywhere.

Have seen the Fuelab pumps and regulators, they have a transducer in the reg and variable speed system for the pump so it will slow down when the fuel demand is lower so less return to tank and less heat. Cant find any mention of this system on a boat but it looks like it will work. Unless anyone has any info why I shouldnt go for this system. Idea is to get the fitting welded to my fuel rail the same as Keith Atlanta above. I have a supplier for Fuelab parts less than 20 miles away.

Some more questions if you lot dont mind...

• Existing fuel line between tank and Racor fuel/water separator is 1/2" ID and uses 1/2"npt fittings, can I still use this line and filter?
• If so the Racor filter inlet is about 10" or a bit more above the level of the tank, does this need lowering down into the bilge?
• Im hoping the Racor 10 micron is good to be the filter that is needed before the pump? Then I will fit an inline filter after the pump to catch anything the pump spits out...
• What size lines to go for? thinking AN-10, but is AN-8 sufficient for my engine? I only want to buy one set of tools for making up the lines. so would use the same for everything, supply and return.
• On the electrical side, will the fuel pump relay on the engine designed to run the two cool fuel 3 pumps be sufficient to run this new pump or do I need to upgrade this also?

Once again thanks for any help.

Your wording is not clear, did he or didn't he replace the regulator in the fuel module ? Open up the module to see if a bunch of crap and paint peeling in there ?

He did not as he doesnt believe he can get hold of the right one. The one that came with this engine looks different to the stock regulator.

So what was he dinking with ? I'm just asking. :)

If you do a custom fuel system, look into the Russell quick connect fittings for GM LS engines. I can't tell you if they will work for the 8.1 fuel rail, but there is a good chance they will. Obviously, a weld on is another choice too.

Russell Push-On EFI Fittings 644113 -6 AN Male x 5/16' SAE Quick-Disconnect Female

Russell Push-On EFI Fittings 644123 -6 AN Male x 3/8" SAE Quick-Disconnect Female

Russell Push-On EFI Fittings 644133 -8 AN Male x 3/8" SAE Quick-Disconnect Female

https://static.summitracing.com/glob....jpg?rep=False

Sorry, there is no 'size' thing on the toolbar to make those letters smaller. Doh !

Both Raylar and Marine Industries West sell adjustable fuel psi regulators that fit in the stock Merc gen 3 cool fuel module. Around $200.

I would have a competent mechanic check It out before redoing everything.

Hello everyone. I thought it right to return with some info as you were all helpful with your suggestions.

Firstly I ditched the previous company that was doing work for me, I wasted so much money and lost a summer of boating to their BS. For example they billed 5 hours messing with the fuel pressure as they couldnt prime it then billed two hours for 'internet research and sending emails', tried to bill £200 for a 20 minute job welding the fuel fitting to the rail as Keith above has on his (I removed from the engine all they had to do was the welding) as they had had to go out and get a pack of TIG wire... at which point I kicked off and parted ways with them.

I installed a Fuelab fuel system with variable speed pump and regulator which works amazingly returned to a fitting in the fuel fill hose into the tank, boat ran better for a while but not perfect. Some other issues then crept in. Researched myself every time and learned a hell of a lot about engines. Found previous mechanic had broken an ignition lead leaving me on 7 cylinders, installed wrong spark plugs, when I asked them to flush the coolant system as the pink colour was starting to fade they had just replaced what was in the tank, it quickly changed back to faint pink again, both block plugs were seized so no chance this was done properly, sea water pump impeller had been changed but the housing was destroyed with scoring so I had a nightmare priming the water system whenever I launched bleeding sea strainer and pump etc, now has the nice Hardin stainless pump which isnt too bad to install now the cool fuel unit is gone, the priming is now a non issue and water pressure is perfect.

Reached the limit of my ability with the repairs and have now found a new company to take the engine issues on which isnt easy in the UK but they seem passionate about performance boats and getting the boat running to its full potential, most importantly they have the correct scan tools needed which the previous company would not invest in.

In the last few weeks an issue was found in the fuel tank, fuel pickup tube was replaced before I bought the boat and the small gause filter from the old one was still floating around in the tank, every now and then this would be sucked into the new pickup tube restricting flow, now this is gone the fuel pressure is perfect. Other issue was the ECU was potentially damaged and unable to be read correctly, after speaking to Raylar it was suggested we replaced the ECU so I went for it and now it is like a new engine.

So now this is all fixed and boat is now running well sitting at 75mph with possibly more to come its a shame that I now still cant use the boat as there is a tapping noise developing near the back of the engine that is being investigated this week. Hoping something small on the top end as the old ECU only read around 150 hours for this engine.

Once again thanks for everyones suggestions and the knowlege I have taken from searching through this site.

Wow! I love the charge for "internet research".
Sounds like your on the right track now. Modified setups generally live up to the BOAT name of Bust Out Another Thousand!

What did you end up setting engine off fuel pressure at?

Dont I know it, kind of knew what I was letting myself in for, wasnt expecting so many p!!s takers in the marine industry but you live and learn the hard way sometimes.

Currently at 50psi engine off, equates to very high 40s when under load, confirmed as the right way to go when the current mechanic actually bothered to contact Raylar for advice instead of just saying they couldnt get hold of them like the last place.

Did you take off all the cool fuel or just install a fuel pump and regulator?
What program is on the ECU? Raylar or Whipple?

Eventually, you will have to get a seasoned pro to read the plugs (the correct plugs) or get an O2 meter. Once you run a separate fuel pump and regulator I believe the correct fuel pressure is in the 44-45 "range" and that is still conservative on my engine.

Cool fuel is gone. Installed a larger Racor filter in line with tank then Fuelab pump and filter down in the bilge then up to Fuelab elecronic regulator on engine which feeds fuel rail and bypasses back to tank, no issues with priming or keeping up the fuel pressure now.

New ECU was sourced in US by Whipple and flashed by them and arrived here last week. Seemed to solve all remaining performance issues.

Was looking at finding a way of installing O2 sensors or testing with a temporary tube type system that pokes into the exhaust as I saw on here a while ago but then the noise became the priority to work on.

What exhaust do you have?

CMI Etube. They have the temperature sensor ports but no ports to fit O2 sensors. Saw somewhere on here that people holesaw the exhaust, dimple the two layers together with a pall pein hammer, weld the layers together, pressure test then weld the ports in as needed, could go that route.

https://www.offshoreonly.com/forums/...sor-bungs.html

I will call Larry one of these days. There has to be a reason for the 50PSI thing. Myself, SD Fever and Rage all spoke on this in detail in PM's dozens of times. We were all in the 43-44 range. Heck, SD Fever was up over 540 cu in with the dry cam and was still only at 46 or something like that....

A simple plug reading done correctly can get you closer than just setting it at 50PSI. I mean at these pressures you are leaving 75 or maybe even more horsepower on the table.

Id be interested to hear the results of your call. Last thing I want is to waste power.

Currently engine is out of the boat, the source of the noise couldnt be found under the valve covers so they're looking in flywheel housing and then onto the sump. Haven't got a good feeling about this.

The 50psi is for a HO525 kit that is using stock Merc 496HO pcm. The 7psi bump in base fuel pressure brings the A/F ratios back into a safe range.

John, Do you have any info on the Whipple pcm? What calibration/tune? I would hope it had a base tune for your setup and not just an 496HO tune?

02 bungs in the exhaust, log data, custom Whipple tune for your setup is the safe way to go. Hopefully your current problem is an easy fix. Good luck.

No info on the ECM sorry, but it is 100% the correct tune for this Raylar engine and not a stock 496.

Thanks for the good luck but Ive just been down to the workshop and based on finding a lot of fine metal in the 25 min old oil which was changed before a short test at the start of the week and a broken oil pickup, the engine will now be completely stripped and checked. The size of the metal looks like hopefully it was caught in time. Cause of the noise still hasnt been found in the upper or lower end but the investigation may have prevented the engine eating itself completely from the inside. Compression now low on two cylinders and white deposits found on two spark plugs in other cylinders, looks like oil burning, also signs of moisture inside engine, head gaskets? Mechanic seems confident the engine is still salvageable worth rebuilding so far so will keep working with it.

May now be some time before Im worrying about fuel pressure but its something I will come back to, if theres performance there to be had Im interested.