525 running rough, back fire?
 

525 issue. Boat was not used for a year or so. Starboard didn't start, turns out a simple slave solenoid. Replaced, started right up. I took out all the plugs, lubed the cylinders, etc. sounds good in idle. Took it for a test ride. Around 1800-2000 rpm, sounds rough, like dieseling sort of. (I think that's what called, when it sounds like wroom wroom wroom, instead of nice even wrooooooooom sound) Plus randomly makes a loud snap, clink sound. I think it's backfiring. Didn't go past 2500, the higher the RPM's the worse it sounds. Idle seems ok. Suggestions? What should I look for or test.?
THX
P

Check fuel pressure on the rails with guage...we had a similar issue and it was the fuel pressure regulator.

also check cap and spark wires...

put fresh fuel in it

If you have a rinda, I’d also do a cylinder cut out test. I had one acting up last year and swapped out one banks coil pack to cure it. Did the other side as preventative measure.

Also, the PCM 555 controller is voltage sensitive so going over connections and hounds might be worthwhile. Ask me how I know... :lolhit:

What's a "rinda".. I'm bad, but ?

Rinda is a scantool

X 2 : check fuel psi

you could have fouled a plug or 2 or 8 :wink when you sprayed ‘lube’ in the cylinders. Replace plugs and make sure their connectors click on.

Start there.

I don't have the scanning tool, but I have the Smartcraft screen. There are some codes I will have to track down what they are. I turned over the motor before I put the plugs back, pushing anything out, so I doubt the plugs are bad. Gaps were good and I cleaned them, but I will check them further. Fuel pressure regulator makes sense. Or even one of the fuel pumps.
THX
P

Well, update: And I need some help.
I hoped I just swapped a plug wire, but no. Wires are all on the right plugs, so it has to be the fuel pressure regulator. It's under the block, near the electric fuel pump, but I can't even see it. How on earth do I get to it and change it.???
Any suggestions? THX

So, you checked the psi ? What was it ?

What where the codes you got on the Smartcraft ?

I didn't check the PSI, for $150 of the regulator, I'll just get new. I have a new electric high pressure fuel pump, never used, so if the pressure regulator won't fix the issue, I'll change the fuel pump. Just looks like a bit(h to swap the regulator. Not sure if I can get to it.

Let me be a voice of reason.

Alot easier and cheaper (free) to see if fuel psi issue. If psi is fine, you saved labor frustration and money.

Autozone and other part stores rent tools free. Ask to rent free a fuel pressure tester.

Also, What where the codes ?

I don't have the codes here at work. I have to read them later this PM.
Merc suggest it may be the coil pack too.

check the fuel pressure. It’s a 5 min job. The shraeder valve is under the cover. Get a cheap fuel pressure guage.

changing out the regulator without checking fuel pressure is a waste of time.

I might even have a pressure gauge. I have one for cyl compression, but I don't even know where to put the fuel pressure connections. On the rail ok. but where and do I need to check the mechanical pump too? I guess it should be 43 PSI I read, but where to put the leads to check?? I need an arrow or a finger to say. " put gauge line here" lol. I'm a good part changer, diagnostics are not my cup of tea. (that why I got you guys for) :)

TTT,
How about a fuel pressure check connection spot?
THX
P

it’s underneath the intake on the fuel rail next to the injectors...

It resembles a tire valve.

Padraig

Thanks, I found it, and of course the gauge I rented doesn't have the right fitting. GGGRRr

OK. Rinda scanner sux. I bought it, installed it, NOTHING. No codes. POS for Merc racing. I called, Now they tell me that their stuff will ONLY read codes, no descriptions nothing. Per Rinda Merc did not "gave" them the info. $600 down the drain. Fuel pressure is around 42-43 at idle. Rinda has a few tests injectors firing. Wires, plugs, etc unknown. Rinda has no clue. While I admit I have no idea with a lot of Rinda stuff, where I click on the button to see codes and there is nothing, Rinda is worthless. Don't waste your $. There is a test to see the coils, so I did it. 1-4 is testable, 5-8 Rinda says "not existing". Supper pissed and frustrated. Then I broke the plastic housing on the ECM connecting wires ( 12 -16 pins, left side, ) and I can put them back. It was stuck, used screw driver to get it off and I broke it. OK that's on me, but no clue how to get the pins back to the right spot.
So, when I install the Rinda thing, there is not even an option for merc. Crusader volve etc. nothing for Merc. I called before I paid, they told me it's ALL good. I will have one hellava conversation in the AM.

I never had a problem with the tech mate. They made one for mercruiser, all the data is available in it.
https://www.rinda.com/marine/mtspec.htm

Troll, you better pay someone to work on your boat!

THat sounds like a train wreck for sure.

Did you end up getting fuel psi Paradox ?

I would love to get some one, can't find anyone working the blue motors and a few that does, way too busy, several weeks out.

Fuel pressure at idle is around 42-43, stay at higher RPM.s All I got to is 1500, but its around 42-43.

I didn't get the Tachmate, got the stuff for the laptop. Should be better with more features. I guess NOT.

I asked the OP, Paradox, and made that quite clear. This is why people should start their own threads. Ugghh.

WHAT?
What does the OP has to do with my headaches? I am the OP, just on a different computer. Why not start a thread about a problem? This is why we pay for this to get input. Yours make no f' ing sense.

OP=opening post to a thread
#1 post is the opening post
Paradox opened this thread see #1 post of this thread.
See the #1 ? Lol
https://www.offshoreonly.com/forums/...ml#post4785878

This is crazy. Lol

So does Peter Paradox have two screen names ?

It's ok, no harm done. Sorry to be rude, just frustrated. Peter Marton and Paradox is the same, I had to log in through Facebook, since on this computer I don't remember my OSO password, Made me log in through face book so I guess it created a mew member. I didn't have the time nor the patience to reset the OSO password on this computer. So, at the end of the day I AM the OP. :)

The Rinda is not a troubleshooter that you just plug in and it tells you what part to change. You have to look at the data it displays, and have to know how to decipher it.

You need to check fuel pressure under load, when the issue is happening. Low rpm/low load/free revving, doesn't use much fuel. I would start here still.

Sure did confuse me. OOPS

Key point above.
To OP, FYI, with the Diacom you can record data.

I thought so from your previous post ....all good

I will take it on the water and check fuel pressure. However, I just talked to Diacom / Rinda tech (BTW very inpatient dude) got to the fault history, nothin major, erased everything, started engine up, NO CODES. All possible descriptions and the screen is zero. Yet, I know I have some since my smartcraft screen show it. Some "pitot" code and a few minor things that I am aware of like tilt chit. It's either my laptop, (doubtful it's only a few month ole ) or the scan. Besides me of course, but there is nothing to interpret or decipher is nothing shows on the screen. Oh. BTW, I managed to put the pins back.

At any rate, I was hoping the Rinda will tell me that I have a spark plug issue, misfire at ? cylinder, fuel issue, coil issue or whatever. I know the PCM records the stuff.

Two screen names are not allowed. Find the time and patience.

How about starting with the basics , Compression , Leak Down and Spark Tests , on all Cylinders .That will give you a good idea of the mechanical health of the engine first. The running rough and Backfires could be a blow head gasket , which is common on the 525s . Post your test findings , them we can help you . Throwing parts at it is a bad way to fix it .The Scan tool will not fix it, or you or tell you what is wrong. It only gives you data to analyze. T

I didn't ask or set up new screen name. Anyone can log in in view. When I tried to reply to a post (as a guest) the system said "Sign in with Facebook". So I did. OSO created the PLM account. A glitch? Anyway. back on PARADOX screen name. THX P

Said you had all the plugs out. You sure wires are on the correct plug?