2006 220 questions-Soot and Fuel pressure regulator

[tr220]

I have a 2006 220 with a VP 5.7 GI-E and DP. It has been a good boat and we love it, but I have a couple of nagging issues that may or not be related.

It would tend to die once in awhile when coming off of the throttle and would struggle to idle smoothly at no wake speed. A couple of years ago I found information on this site about the IAC valve going bad. I replaced it and it immediately fixed that issue. I have recently started to suspect the IAC is starting to fail again. What brand of IAC works best? The VP part seems ridiculously expensive. Then there is GM or ACDelco. Then there are a large number of no name cheep ones. Is something like Standard Motor a good middle ground? What does everyone use?

The second issue is soot buildup on the transom and a little on the sides at the water line near the stern. This came on gradually last year. I assume it is running rich, or a cylinder is not working properly. I am fairly convinced that the over rich condition occurs at startup. Most of the accumulation is on the transom. I think what accumulates on the sides does so when I am backing out of my slip. I don't sit at idle for minutes after starting and before backing out. I just cast off the bow lines and go - maybe 30 seconds to a minute at most. At that point the engine is running at about 700 rpm and sounds smooth. Overall fuel economy has not changed. It uses 7.5 - 8 g/ tach hr. Performance is fine. I have checked all of the plug wires and replaced the cap and rotor (the old ones were not corroded or eroded.) I have recently added Seafoam and BG 44K to the fuel, but it will be awhile before much gets run through the engine.

I am considering sending my injectors in for cleaning and testing at the end of the season. I could see how poorly functioning injector or two could cause incomplete combustion. I can tell they have never been off. The paint is still fully covering the nuts holding down the fuel rail assembly. Where is a good place to send them to?

Where else can I look for suspects?

Thanks

C_220_transom.jpg

C_220_soot.jpg

[SAB220]

The Idle air control (IAC) valve is located on the throttle body of fuel-injected engines. It works with the ECU to electrically regulate airflow to the engine to ensure smooth idling. I guess it could affect something underway but its for idling and make sure you change the little nylon filter sitting in the throat of the throttle body at the same time. I only purchase OEM parts to dismay any questions like this.

Soot - pull the plugs. They will tell you the story, and match them up against lean plugs. Replace them with NGK Iridium Spark Plugs.

[Big Block Power]

Welcome. Cmatt posted on this same issue on soot awhile ago and I believe he said that premium gas can cause this. If you go to 87 which I know is hard to get on your lake that may take care of this. Or if could be caused by your stalling issue. Replace your iac motor. Standard is a good brand. Honestly I've even used the cheap Chinese ones and had good luck. I even keep a spare one on board. Really you shouldn't need to get your injectors flushed but it could help maybe. They are self cleaning on the pintel valve inside of them. But yes they still can get plugged a bit. 1 member here sent them to a place in texas with good results. I think it was xlint that sent them in. I was think of sending mine in but for a diff reason.

[tr220]

Thought I would post an update in case anyone else comes across this issue. I replaced plugs, wires, cap, and rotor with oem. No change - soot buildup on every run. After some further investigating I got a fuel pressure gauge. The pressure at idle was over 100 psi not the 50-60 it should be. No wonder it was running so rich. I replaced the fuel pressure regulator and the problem was gone immediately. It idles cold and hot just fine now. Acceleration is better and there is no lag at all, even cold. I am sure fuel economy is better, but I have not had enough thru it to tell what it is now for sure. And it runs quieter now. I am sure the hp pump was making noise and immediately stopped when the pressure was normal. Hats off to Troy at Mancave Mechanic. He was very helpful during the process.

[SAB220]

tr220 - Thanks for coming back and telling how you solved the problem

Did you do it, or have it done? Difficulty? Where is exactly? Next to the fuel rail ? What the P/N if its handy? I'm all wrapped up for the season but I'll look into replacing it next spring. I tuned it up before I put it away because it needed it (new impeller too) but ya hesitation problem (shutters). Tried to return the $300 OEM coil and they said keep it, so I installed that too

[Big Block Power]

It's a good thing to look at for paint flakes on the screen as well. Will be checking my screen this off season. I take it you put a Guage on it?

[tr220]

I did it. Very easy. I borrowed a gauge from O'Reilly's. Once I verified the problem I ordered a new fuel pressure regulator from Mancave Mechanic. VP part# 3858967. The VP part appears to be made by Bosch and the one I received looks like a Bosch too and it was 1/5th the cost of the VP part. It is a 4 bar (= 58 psi) rated fpr. It's located on the top port side of the fuel rail. Troy said to just poke a hole in the screen on the old one, but I preferred to replace it. The old screen did have what I assume was paint flakes, but it was more like dust than flakes. VP has a bulletin out to just remove the screen and replace it with a special clip. The plugged screen apparently causes the return flow to drop so low that it can cause the hp pump to cavitate. I had incorrectly attributed the noise to belt noise and inquired twice when I had the boat at the dealer's for outdrive service, but they said it was ok. Within a minute of replacing the fpr and starting the engine the noise went away.

Troy has an excellent video on YouTube showing how to do all of this: . He has several videos on the fuel pump system that are very informative.

I suspect the high fuel pressure and subsequent soot deposits hastened the demise of a couple of IAC valves. They always had a lot of soot on them when I replaced them. Another clue I saw was that all spark plugs had soot deposits, not on the electrode but on the inner shell. I knew it was not just one or two cylinders causing the problem. It was all.

[AsLan7]

.
Nice follow up Tr220...great vid too for others.

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[jhnmdahl]

Great content - thanks for sharing your solution!

[Big Block Power]

Yes the VP service bulletin is due the 5.7 engines. Not sure why the 8.1 isn't in it?

[DEcosse]

Thanks for linking that video - very interesting & great info

... The VP part appears to be made by Bosch and the one I received looks like a Bosch too and it was 1/5th the cost of the VP part.

I had similar experience with my 8.1 Throttle Body - VP was $850 list, I could find discounted for $600.
After researching found it was an AC Delco part - all VP does is slap some Red paint on it.
I paid $92 incl Priority Mail shipping for brand new AC-D part.

I imagine this applies to a great number of the engine parts that are other than the specific VP marine parts - match up your motor to the equivalent GM model and search for the automotive part.

[SAB220]

OEM (43 PSI) Fuel Pressure Regulator Kit 861126A1 w/ filter and o-ring $185
If the OEM one lasted 20 years then why question...
Replace it in the spring
Thanks tr220

[Titaniumboy]

Should the title of this thread be changed to reflect the underlying problem found?

[AsLan7]

Should the title of this thread be changed to reflect the underlying problem found?

…I changed the original title.

[Titaniumboy]

Wasn’t the problem a bad fuel pressure regulator?