Closed Cooling System on Port Engine Running Hot(ter)

[alldodge]

I think the only issue is if the injector seals are OK. The rail will not be an issue, its only the seals and they are cheap enough

 

[achris]

Ted, I have been looking at the GM MEFI manual (the link I posted). WAAAAYY better than anything in the Merc manual. It gives a very good description of the entire system, including how to replace the regulator. Even has cross-sectional drawings of every component in the system. Description on removing the regulator (without the rail) is on page 3D-15, but it's at the back of the engine, I don't know what your access is like.

When diagnosing the ECM 'fault' (constant errors), I'd start with a couple of basics. First check all grounds, then using a good digital meter check the ECM 5v and 12v lines. Although, the 5v is produced inside the ECM and swapping them showed no fault on the ECMs. Doesn't mean something on the port engine is pulling the supply down a bit though. So worth checking. And also the 'ground' reference for the 5v is not engine ground. You need to find a 5v reference ground, terminal 'B' of the TPS is such, black wire. Anyhting '12 volts' is actually battery voltage. Also worth checking for something drawing it down. A good place to check the 5v is terminal 'A' of the TPS, colour gray.

Chris......

 

[tpenfield]

OK, thanks Chris, AD, Rick, Scott and others for your help along the way. :thumb: hopefully this fuel regulator issue will pan out and be the solution.

The regulator is at the front of the engine. I'll dig through the MEFI manual some more. I think if I remove the plenum and maybe the heat exchanger and the thermostat housing, then I will have enough access.

AllDodge - did/does your engine (on the Formula 27PC) have the same fuel rail as my engine?

I am just trying to fit my 'repair plan' into my overall schedule. We have a ton of folks coming this weekend for beaching and boating. So, I was going to work on the engine on Friday, and wanted to at least do the fuel regulator, but concerned about opening up a can of worms.

If it were the off season, then I'd probably take the whole thing apart.

My game plan for Friday would be:

Replace fuel regulator
Test fuel pressure
Run Engine, check temperature and Diacom stats.
Check compression
Borescope valves
Hopefully, everything will be OK

I'll leave the starboard engine alone for now, that can wait until the off season, I think, since the fuel pressure was 40/34 psi.

 

[tpenfield]

Looks like the MEFI manual covers the next generation of fuel system. My engine has a single fuel rail with the regulator underneath the rail at the front of the engine.

The MEFI does have a lot more detail than the Merc Manual #16. I am wondering if Pleasurecraft has an earlier version of the MEFI manual :noidea: I'll do some Googling. . .

 

[alldodge]

did/does your engine (on the Formula 27PC) have the same fuel rail as my engine?

Originally yes, currently no. Mine has been modified during the rebuild, the regulator remains on the front under it, shrader valve has been moved to accommodate the main fuel feed.

 

[mr300z87]

Ted. I have continued to follow this as I find it intersting but even though I am having an minor issue with my 5.7L the carb sounds simple compared to the mefi. One tip I learned about working on a high fi engine is to disconnect the power to the fuel pump and crank the engine over. This releases the fuel pressure in the rail. I can't be of much more assistance than that but I am rooting for you. Mike

 

[tpenfield]

Ted. I have continued to follow this as I find it intersting but even though I am having an minor issue with my 5.7L the carb sounds simple compared to the mefi. One tip I learned about working on a high fi engine is to disconnect the power to the fuel pump and crank the engine over. This releases the fuel pressure in the rail. I can't be of much more assistance than that but I am rooting for you. Mike

Thanks, Mike. I may try that. Another thing that I was thinking about is to use the pressure gauge to drain the rail, since it has a relief valve. It seems that the service manuals are a little vague on the finer points of replacing parts. I'm sure they figure that folks using the manual will have to add some of their own knowledge and insight.

I have been Googling a bit and have not seen anything picture or video that covers the type of fuel rail that I have. I think the particular design of fuel system that I have only lasted for a couple of years and was replaced by more maintainable versions

 

[tpenfield]

One thing about the fuel rail and injector system on my Mercruisers that I cannot quite understand is how a single rail system on a V8 engine goes together or comes apart :noidea:

I can see how a 2 rail system on a V8 connects to the injectors on each side of the engine, since they all line up. But on a single rail system, I am not seeing how it goes together.

Here are a few pictures of the VST / single rail system that are similar to the one on my engines. Note the angle of the injectors as they are attached to the fuel rail (red lines) . . . those injectors are in turn supposed to insert into the intake manifold . . . but the geometry escapes me :noidea: HELP !?!?

This looks like the system on my engines . . . probably exactly what I have.



...
similar setup with a view of the rail and injectors from the underside. Don't see how these can go into the intake manifold with the 2 different angles as shown by the red lines . . .



I'm sure they do go together, I just don't understand how at this point. TIA for any explanations.

 

[alldodge]

The 4 holes on the top of the rail are used to bolt the rail to the manifold. The injectors use clips and gaskets to hold them in place on the rail. The gaskets on the injector ends seal the injector to the intake. The ports are there and resemble the bolt holes. These intakes are great for making torque

 

[tpenfield]

AD, I understand where everything bolts and where the injectors go, etc. What I don't quite understand is based on the 'V' shape, the thing should not be able to go together, unless there is a fair amount of play in the rail and manifold openings for the injectors :noidea:

I did notice that one side of the rail is 'deeper' than the other side . . . so maybe that is the trick . . . the deeper side goes on first and the shallower side 'snaps' into place :noidea:

 

[tpenfield]

Just reviewing the manual, there must be some play in the rail holes as the procedure says to work from front to back for removal and back to front for installation.

 

[alldodge]

Yes, they are not bolted solid, the seals do all the work once installed, just need the bolts to keep them in place by holding the rail

 

[tpenfield]

Yes, they are not bolted solid, the seals do all the work once installed, just need the bolts to keep them in place by holding the rail

OK, thanks. I'm going to try to replace the pressure regulator without disturbing the rail and the injectors. I might have to loosen the rail a tiny bit.

 

[tpenfield]

I got my parts today and will be taking the next 2 days off from work to get the boat ready for the weekend. I figure if things get messy on Thursday, I have Friday to recover. Else it is sail boat time

 

[tpenfield]

Four Flag disaster today . . . :facepalm: :faint2::flame::yield:

The pressure regulators ( I got 2 of them) were both defective. I got them off eBay from what looked to be a reputable seller. I think I was a little too quick on the 'Buy Now' button, as they were an after market part, which would have been fine, if they worked. they only go to about 28 psi and do not hold pressure long at all. I put the original regulator back in just to be sure and that held 30 psi.

Now I am in a jam, trying to get a regulator locally. The Mercruiser guy in town does not have any. NAPA - Nope. Trying a few other places in the morning

eBay is real hit or miss . . . today was a miss. :grumpy: :mad-new: :facepalm:

 

[alldodge]

That's a real bummer, both with the same low pressure

Where they both listed as new or used?

 

[tpenfield]

That's a real bummer, both with the same low pressure

Where they both listed as new or used?

They were new and listed as such. . . . Gonna send them back for a refund. I did a basic test on my workbench this evening using air pressure, and they seem to regulate low and one of them I can hear leaking.

But that is the least of my worries at this point. I want/need to find the part locally tomorrow AM. I have a list of 7 Mercruiser dealers in the area so I'll be dialing for part in the morning.

 

[achris]

The Merc part number for the regulator is -805227A1, and should cost about $100 each.

 

[tpenfield]

The Merc part number for the regulator is -805227A1, and should cost about $100 each.

Yup, $90 is what my go-to Merc dealer quoted on the phone yesterday, but he had none in stock.

I wish I could just download one from the Internet

 

[NHGuy]

Make sure to check Doug Russell in Worcester, they have their best pricing on their ebay store, but will match it in person. Not that close to the cape,but they have oe stuff priced well. and they are pro's.