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knotguilty    6

This has been the year of "extended maintenance" for my 2005 Avy. The real trouble started with a stuck fuel injector earlier this year. I limped the boat back to the dock (20 minutes to go ~3 miles) with white smoke and un-burnt fuel coming from the exhaust. The computer was throwing a injector group #2 stuck open error. I replaced all of the injectors, inline fuel filter and water separator. I also changed the oil and oil filter because the oil had 2 quarts of fuel in it.

 

The next time I took the boat out, the boat started and 2-3 seconds later the engine died. The only way the boat would start was to crack open the throttle but once it started and warmed up it ran but would run rough at idle. After doing some research I replaced the IAC ( and the muffler that goes with it. The muffler was clogged up before I replaced it. Since then the boat would start with some hesitation but it would run very rich and unstable at idle. Anything above idle the boat runs great.

 

I have hooked up the Rinda computer and tried doing a IAC test. The RPM does not change when I try to open and close the valve. (RPM bounces around between 580-650) I have also tried cycling the valve without the engine running and the rod does not move. However, the valve will make a buzzing noise around +30%. I put the old valve back on and it acts just like the new one. I have bought 2 IACs and between the old one and the 2 new ones they all act the same. The 2 new valves are a Standard AC423 and a BWD 50558. This is what the Mercruiser 862998 cross referenced to.

 

Interestingly enough after running around 2000 RPM for 15 minutes or so the IAC Duty Cycle reads ~30% when I first go back to idle. The boat runs pretty good here. However, the longer I sit at idle the more the IAC Duty Cycle will creep back to 99.9% and the boat will run rougher and rougher with a strong smell of gas and black exhaust. Does anyone have any experience with trouble shooting an IAC? Shouldn't the Duty cycle sit a close to 30%? Shouldn't you be able to move the IAC with the Rinda back to a point where the engine pretty much starves of air at ~-90%? I'm getting a bit concerned that I'm looking at a new ECM...Any thoughts on where to go from here?

 

I have already checked the resistance of the valves (12.5 ohms). I also checked the resistance back to the ECM and that checked out. The ECM will send a warning signal (2 beeps) only when the IAC is disconnected. The harness is reading battery voltage (12.4 Volts) with the engine off.

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nnoia05    0

how about your fuel pressure? i noticed there is a fuel pressure regulator mounted on the fuel cooler with a vacuum hose going too it. if it were bad or having problems it would give you a rich condition.

 

as far as your iac, i have a rinda scan tool, next time i go out i will have a look at mine and see what it does. i'm also fighting through a problem right now, i have the engine beeps and dies thread.

 

i was leaning towards an ecm for my 04 avy, priced it through my local merc dealer. you want to hope its not that, list price was $1700. nad he said there are only 2 in all of US. he told me these ecms are extremely rugged and dont go bad easily, he has only replaced two in the last 10 years, one still worked customer just wanted it because the boat sunk. other one the guy hooked the battery up backwards and fried the ecm

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What has me puzzled is the 2 quarts of fuel in the oil. How in the world could that much fuel get past the rings? Assuming it happened when the trouble started. That's very scary. Have you ran a compression test on number 2?

 

Nnoia05 I was hoping you got yours sorted out by now.

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truekaotik    460

Check your cap and rotor.....

Edited by truekaotik

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Shaka    138

I'm wondering if this is my issue as well. I replaced my cap and rotor a few years ago so I should probably check that. My boat is having an issue where it doesn't want to start unless I give it a little gas. Once started it runs a bit rough until I take off then everything smooths out. I usually do not have the problem again until my boat sits for a bit.

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knotguilty    6

I forgot, I replaced the cap and rotor as well when the rough idle started. Checked the compression tonight; 170 PSI on all cylinders +/- a few PSI. Looked good. I borrowed a fuel pressure gauge but I don't trust the gauge. Said I had less than 5 PSI. I had the boat doing 40MPH with 2 people and no hesitation this weekend. I'm thinking high pressure (45+) not low. I have a fuel pressure gauge on the way from Amazon.

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knotguilty    6

When I pulled the plugs to do the compression check the plugs were black. Lots of carbon, indicating once again she is running rich. Not surprising but worth mentioning.

 

As far as the 2 qts of gas I'm thinking it was not just one injector. This ECM controls the injectors in 2 blocks. I think one block shorted out and opened up 4 injectors. In 2 miles I went through 15 gallons of gas. Yeah, I didn't think that was possible either.

Edited by knotguilty

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That's good on compression. Real good. Yep it wouldn't even crank with that low of fuel pressure.

 

What about that fuel in the crankcase? Only one way in really is around the rings. Unless I'm missing something.

Is it possible the injector allowed fuel to leak down or syphon fuel from the rail? I've smelled engine oil that smelled like gas but a half gallon of gas in the oil is way beyond excessive. I don't think you could pour it down the Intake and get that much in there. The compression check is good so valve guides are good. Seems like something is going on with the fuel system. More than just a rich condition.

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Oh that makes sense. Man you are lucky you caught that. So fast you could have destroyed a rod, main or cam bearing. Wow.

 

I hope you get it sorted out. I'm curious how these engines handle the a/f ratio. No o2 sensors that I've seen.

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knotguilty    6

Nnoia05, There are 2 fuel pressure regulators. One on the lower starboard side on top of the fuel cooler and one on the fuel rail where the fuel comes in on top of the engine.

 

The fuel regulator on the fuel cooler is set to 43 PSI. Does anyone know what the one on the fuel rail is set to?

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Shaka    138

What kind of gauge do you need to check fuel pressure?

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I'll check my pressure at idle if it helps.

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knotguilty    6

Checking the pressure on a good running boat would be helpful. Also if anyone has a Rinda and wouldn't mind running a IAC test and let me know how much the RPMs change. Mind does not change at all which has me concerned.

 

My fuel pressure gauge comes in today so I should know more this evening.

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knotguilty    6

I checked my fuel pressure. When I turn the key the pressure is rock solid at 43PSI until the pump goes off. Once the pump stops and before I start the boat the fuel pressure drops to 38PSI. Once i start the boat the pressure bounces between 36 and 43PSI at idle. I tested this in the driveway so I didn't go to higher RPMs. Is it normal for the fuel pressure to bounce erratically at idle? I'm thinking I may need a new regulator. The one on the fuel cooler. Apparently the regulator on the rail is a dummy but can still go bad according to the manual. Yeah for extra parts!

 

As far as the IAC and the computer all is good there. I checked the DC and AC volts and everything checked out. Even though the control is a square wave duty cycle RMS voltage tells me the control is sending the right signal. I measured the voltage from the Black and Green wire (IAC grounded control) and the sky post (best ground I could find). Results below for reference:

 

%Duty Cycle

(Rinda) AC(V) DC(V)

100 0.0 0.0

90 2.3 1.15

80 4.4 2.26

70 6.6 3.35

60 8.7 4.46

50 10.8 5.54

40 12.8 6.64

30 14.7 7.27

20 16.6 8.81

10 18.5 9.87

0 19.9 10.74

 

Before engine start the valve was controlled to 0% and idle immediately after start was at 100%.

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I didn't have my fake lake, I cranked it for about 3 seconds. 45 psi or about was idle fuel pressure. Mine did not fluctuate for that amount of time. That's like a 20% drop in yours, I do not think that's good.

 

If you have no new data by Monday regarding fuel pressure I'll get you all sorts of numbers, I'll take my gauge with me to the lake.

Edited by Tommywalton1974

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knotguilty    6

Tommy, Thanks for testing. That helps. Was the fuel pressure steady?

 

 

Sent from my iPhone using Tapatalk

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Yes. For those few seconds. I knew it had a little water in the impeller housing so I ran it just a bit. Mine has a brand new fuel filter on it also.

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Is that your engine? Is that a crossfire distributor cap? My gauge doesn't jump like that. Your valve seals shouldn't be covered in anything but oil I hope.

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knotguilty    6

Yes, that is my engine. Made the videos last night. Not sure what you mean by cross fire distributor cap. The cap is not Murcruiser. It is a standard 350 small block rotor and cap.

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knotguilty    6

So back to the fuel pressure. Sounds like replace the fuel regulator on the cooler first and go from there?

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So back to the fuel pressure. Sounds like replace the fuel regulator on the cooler first and go from there?

Ha sorry just looks nothing like my set up. I'm just not sure that fluttering gauge means the regulator is bad. I'm going to get you some video of mine when I put it in the lake.

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knotguilty    6

I replaced the fuel pressure regulator in the cool fuel box and the fuel pressure looks steady now but is still running high around 38 psi. The idle is still rough, sounds a bit like a Harley in the water. Sounds like "potato potato potato". The exhaust still smells really rich and I get a black layer of soot like stuff all over the hull near the exhausts (Sideswipe). Vacuum is still running low 12 inhg. Which may explain the high fuel pressure and rich idle. Compression looks good. I can't explain the low vacuum. I've measured it straight at the intake manifold and still low. I have a 555 ECM so timing should be good but I checked it with the scan tool and it is bouncing all over at idle. Rpm is also bouncing between 575 and 630. Does anyone know where the ECM gets RPM? Cam position sensor?

 

One more note, I checked the duty cycle at the IAC. The computer and the duty cycle gauge read the same. I tried 2 new IACs and they reacted the same. They didn't move when not on the engine but I have to assume the airflow helps push the actuator.

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knotguilty    6

I replaced the fuel pressure regulator in the cool fuel box and the fuel pressure looks steady now but is still running high around 38 psi. The idle is still rough, sounds a bit like a Harley in the water. Sounds like "potato potato potato". The exhaust still smells really rich and I get a black layer of soot like stuff all over the hull near the exhausts (Sideswipe). Vacuum is still running low 12 inhg. Which may explain the high fuel pressure and rich idle. Compression looks good. I can't explain the low vacuum. I've measured it straight at the intake manifold and still low. I have a 555 ECM so timing should be good but I checked it with the scan tool and it is bouncing all over at idle. Rpm is also bouncing between 575 and 630. Does anyone know where the ECM gets RPM? Cam position sensor?

 

One more note, I checked the duty cycle at the IAC. The computer and the duty cycle gauge read the same. I tried 2 new IACs and they reacted the same. They didn't move when not on the engine but I have to assume the airflow helps push the actuator.

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