Closed Cooling System on Port Engine Running Hot(ter)

[tpenfield]

I think we might have a 'winner' . . . Port engine plugs look like they are running quite lean. Starboard engine plugs look more normal. I took some pictures and will post them later.

Also, with my new timing light, I was able to get a better reading on the ignition timing. I did not have my manual with me, so I was not able to set it to base timing mode, but by comparison the port engine looks like it is a few degrees less advanced than the starboard engine.

So at this point I have the following questions:

How best to fix the fuel mixture issue ? Run a high concentration of injector cleaner? new injectors,? take them out for cleaning?

Would the timing being off by a few degrees cause a lean condition?

Would there be damage to the engine from running about 30 hours in a lean condition? My assumption is that it got progressively worse between last season and this season.

Thanks for any thoughts or inputs.

 

[alldodge]

port engine looks like it is a few degrees less advanced than the starboard

Port has the heat problem but port is running less advance then the starboard. Things that make me go Hummm
Could be the computer doing it due to a MAP sensor, fuel pressure, or vacuum leak.

Since all the plugs are running lean then I would start with fuel pressure and see if it's up to around 37psi. If it was a few of them (plugs) then I would lean a bit to injectors need cleaning, but all, that to me is a system issue. Could also do it with a vacuum leak but your not having idle issues

 

[NHGuy]

That would be good if you could nail it down to fueling. I don't speak efi, will defer!

 

[tpenfield]

Here are a couple pictures of the plugs. I did not take them all out, since it was pretty obvious once I removed a few. I also removed one of the starboard engine plugs just for comparison

Here is the #1 Port versus the #2 starboard (both outboard plugs . . . easy to reach


The starboard engine isn't exactly running rich, but the port is definitely running lean.

Here are #1, #3, #5 of the port engine. #3 looks a little bit different. the #1 and #5 definitely have a greenish hue to them . . . the #3 plug was a bit more purple than green.

So, I'm thinking that I should check the pressure on the rails and probably run a concentrated mix of injector cleaner through both engines and see where that lead me :noidea:

 

[alldodge]

You could try the injector cleaner, but I would check pressure and see what that lead me to. Hope you can keep the gauge on it for a run.

It will be hard to get at, but I would be real interested in seeing plug #7 on the port motor. That's the injector hole that can run lean with good pressure due to a bad mold design

 

[tpenfield]

You could try the injector cleaner, but I would check pressure and see what that lead me to. Hope you can keep the gauge on it for a run.

It will be hard to get at, but I would be real interested in seeing plug #7 on the port motor. That's the injector hole that can run lean with good pressure due to a bad mold design

Actually, the odd numbered plugs on the port motor are the easy reach. I just stopped at #5

 

[Scott Danforth]

Glad you are honing in on the issue

 

[tpenfield]

Some how I double posted above . . . :noidea:

Anyway, there is not much info that I have found so far on hooking up a pressure gauge to the fuel system. My engines have the VST fuel system (I believe) and the manual #16, which covers my engine briefly touches on it, but that's about it. I also have manual #23, but those are for a few model years later with the cooled fuel systems.

>>>> MPI fuel systems are a bit new to me . . . Any help there? It looks like from web surfing, I can connect a pressure gauge by installing a "T" fitting to the line leading to the VST tank ? Looks like the fuel pressure should be 34-38 psi. I am assuming the fuel pump creates that pressure and the regulator 'manages' it?

>>>> Also, any way that I can assess the possibility of damage to the valves, etc. from running lean? Lots of folk lore out on the Internet about lean conditions, tuliped valves, etc.

>>>> I am wondering if I should bite the bullet and get the Rinda Software and accessories to read codes, etc. ?

Overall, the engine performance has been fine, but maybe there are some codes to be read from the MEFI1's. ?

 

[tpenfield]

Port has the heat problem but port is running less advance then the starboard. Things that make me go Hummm
Could be the computer doing it due to a MAP sensor, fuel pressure, or vacuum leak.

Since all the plugs are running lean then I would start with fuel pressure and see if it's up to around 37psi. If it was a few of them (plugs) then I would lean a bit to injectors need cleaning, but all, that to me is a system issue. Could also do it with a vacuum leak but your not having idle issues

AD - I have been thinking about what you wrote. Definitely true with EFI/MPI engines. If the sensors are giving false or inaccurate readings then the fuel mixture could be off. The sensors and the fuel system itself are all inter-related. So, it seems like I should be going through everything.

Just looking at the parts diagram for my engine, it looks like I have:

MAP Sensor = P/N 864865A1
TPS (throttle) = P/N 805226A1
MAT (Intake Air Temp ???) = P/N 805223T
IAC (Idle Air control) = P/N 805224A1

So, it seems like I should really get the Rinda software to see the specific sensors readings and to see if the engine has thrown any codes. I also plan on getting a new distributor cap & rotor for both engines as the ignition timing was jumping around a lot when I checked it over the weekend.

I'm still searching the web for information on the types of false sensor readings that *could* result in a lean running condition. I'm also thinking that the starboard engine may be close to running lean, based on the plug that I pulled. :noidea: So, I should make sure that engine is within spec's as well.

 

[achris]

Time to invest in the Rinda software and set it up on a laptop. Fortunately you have 2 engines side by side to compare. BTW, I have the software, excellent. A miriad of data, and some of it useful...

 

[alldodge]

>>>> MPI fuel systems are a bit new to me . . . Any help there? It looks like from web surfing, I can connect a pressure gauge by installing a "T" fitting to the line leading to the VST tank ? Looks like the fuel pressure should be 34-38 psi. I am assuming the fuel pump creates that pressure and the regulator 'manages' it?

Yes, manual 16 is the one, and if you look on page 5C-60 it shows an illustration of the fuel service tap. That tap is a shrader valve which allows the pressure gauge to be attached. Running one from a line going into the VST just gives you your low pressure pump output.

The scanner will give you some insight but not a lot for the MEFI-1. The 1 just doesn't have much resolution but will provide info on your sensors. I removed my 1 and VST when upgrading to MEFI-3 system.

As far as damage to the valves, that can be check with a compression test, and if its weak then do a leak down.

This is all the info for the MEFI's in list form


I have the scanner and I was running rich prior to rebuild. Should have looked closer at the MAP but nothing stood out at the time, but from the list you can see there is not much it will tell you.

 

[tpenfield]

Thanks Chris & AD, your comments and postings are very helpful.

Just getting over my Monday morning 'coma' at the office . . . how did I get here? . . . last thing I can remember, I was on the beach yesterday

I ordered the Dist. Cap & Rotors and took a look at the Rinda/Diacom web site. Looks like they (Rinda) do not have online ordering, so I sent them an email asking how to proceed. They have a price on their web site of $579, but the retail places that I could find seem to have it at about $700 $579 would be better :thumb:

I'm wondering if I can get it in time for the weekend? :noidea:

I * think * my plan for the weekend it to:

Check for codes and senor readings (if I get the software)
Remove/check/clean all of the sensors
Check the fuel system pressure
Install new cap & rotor
Set the base timing
Check the compression

I suppose that I will know if the engine is running at the proper fuel mixture, if it suddenly runs cooler.

 

[tpenfield]

Given that I have the fuel pump that runs off of the seawater pump housing, I assume that I have to have the engine running vs. maybe with an electric fuel pump, just have the ignition 'on'. (right?)

 

[alldodge]

Just turning the ignition on will energize the VST. This will give you the initial reading, but if there was any drain back of fuel, it may not be accurate. Best to have the motor running for full pressure check

 

[tpenfield]

I got the Rinda Diacom PC software (94010 kit ) on order . . . so hopefully I should have it by Friday.

 

[achris]

I would only remove a sensor if it is showing faulty. You're likely to introduce more faults than you fix if by removing them. As for the Diacom software, when you have a file saved, could you send it to me? I can have a look at it on the software I have too. Get a file from each engine.

Chris.....

 

[tpenfield]

I would only remove a sensor if it is showing faulty. You're likely to introduce more faults than you fix if by removing them. As for the Diacom software, when you have a file saved, could you send it to me? I can have a look at it on the software I have too. Get a file from each engine.

Chris.....

Will do . . . I think the latest version of the software is 'version 2.99'. I will probably load it onto my Windows 10 Laptop, but I assume the data file is the same regardless of version. I assume that the software will indicate sensors that are not reading correctly :noidea:, but I guess we will see. The last time these engines were hooked to this type of software was during the pre-purchase survey.

 

[achris]

Yes, the data file is just a rtf (readable with Word), but I'll import it to my Diacom. The sensors will just show a value, you'll need to either know what you're looking for, or compare the engines. The sensors will only show faulty if the value is hard to ground or open, not an incorrect value. I have Diacom 2.9.2, guess I should download the updates....

Chris.......

 

[tpenfield]

I should have all the parts and tools that I need to diagnose the engine fuel mixture by Friday.

I have in hand or on the way the following stuff:

Rinda Diacom test software kit (#94010)
Fuel System pressure Tester (bought locally)
Distributor Caps & Rotors
Sensor Cleaner (MAF) CRC Brand . . . Which I assume I can use for pretty much everything that needs cleaning :noidea:

I need to grab an external CD/DVD drive to install the Diacom S/W, 'cuz my new laptop does not have one . . . and a USB extender cable so I can run diagnostics at the helm of the boat.

I also thought that I would grab a newer/better inspection camera to get a view of the exhaust valves when I pull the spark plugs for the compression test.

It seems like on bigger repair issues like this I tend to acquire lots of new 'tools'.

I would so like to get this sorted out quickly as there will be a ton of family folks at 'the Cape' this weekend and the only other boats we got in the extended family are a 22' Grady and a 13' Boston Whaler

 

[alldodge]

It seems like on bigger repair issues like this I tend to acquire lots of new 'tools'

Sorry to hear your having the issues, but more tools makes me giddy