VP 8.1GXi Fuel Pressure / Hunting at Idle

[JNelson90]

Agreed, the hardest part for me is that I take great care of my boat as well and probably go above and beyond on all maintenance and winterizing so it is frustrating to have a catastrophic engine failure. My fuel pumps, both high and low pressure had quite a bit of paint chips in them and I suspect this ultimately was responsible for the lean burn and catastrophic engine failure. It would be nice if Volvo Penta or Carter took responsibility for painting the insides of the pumps. I am heading down to the marina on Thursday to hopefully get more answers. I will update as soon as I can.

[gofast24]

Yes, so catastrophic (and expensive) of a failure due to a fuel pump supplier spraying a little paint into areas it doesn't belong in!! You would think that fuel pump suppliers et al would be smart enough to not do something that stupid? Good luck trying to get some compensation from VP or their fuel pump supplier, not very hopeful that you will get anything but worth a try! If you do anything put it in writing to VP and use the words "latent defect in material or workmanship". This means that there was a defect that didnt show up within the warranty period so , therefore, "latent", and beyond your control. I spent 47 years in the diesel/gas OEM engine business in various duty's including R+D, test and development, applications engineering, and as getting older to technical sales. Not bragging just want to fill you in on my career prior to retiring in 2008 Good luck and keep us in the loop!

[JNelson90]

Thanks again for your direction and insight. I spent one full day with my marina mechanic and we were not able to fix the engine. We had a few error codes but they were probably from the testing withe some things disconnected. We swapped parts from the working engine to rule out everything - MAT, MAP, Knock sensors. Even swapped ECU but the problem persisted. My last thought is the throttle body and/or gasket and intake manifold gasket. I had replaced both throttle bodies 3 years ago but I guess it could be bad again (IAC - Idle Air Controller) or they reused the old gasket when re-assembling my engine. I have ordered 2 new throttle body gaskets so I can do a swap before I am off to another marina as my marina is basically say that they cannot fix it. FYI: also found out where the several inches of water in my bilge are coming from; my marina replaced the drippless seal on the prop shaft while the motor was out (made sense) but my new dripless seal has a constant drip. I keep repeating to myself "I love boating" but boating implies the ability to drive the boat.

[gofast24]

Jeff, thanks for the update! Might want to be careful about switching ECU's from one engine to the other, I believe they are programmed to operate a specific S/N engine? The mechanic should have recorded the fault codes before switching out sensors/switches! Also, your good idea, take the vessel to another marina with a VP certified mechanic or call VP and ask them for a recommended dealer in your area!
Regarding your drip less fitting I have learned over the years "if it aint broke, dont fix it" (But do service it as recommended by the manufacture)
Good luck and yes, part of boating is being able to drive the boat, the other part, in our case, is just hanging out at our covered dock with slip mates for a short weekend. We are happy that with a 2001 we havent had any problems with the expensive stuff, i.e. engines, gears, gen set. Just little expensive stuff!

By the way, where are you docked, lake, ocean, or inland waterway?

[JNelson90]

I did document all the codes before they were cleared and swapping ECU's was recommended by VP mechanics from the other marina working in co-operation with my marina. I am on the Connecticut river about 11 miles from Long Island sound so the water is basically fresh water at our marina. Thanks again.

[gofast24]

Thanks,
So now the big question, what did the codes pulled indicate? Hang in there, soon you will be actually moving over the water again:) If you dont know what the codes mean, there are a lot of folks on the ROF that can probably help with that.

[JNelson90]

Sorry but I don't have them with me as they are down at my boat. They were both intermittent (i.e. showing starts since code last set > 10/40) - if I recall; one was DTC-0118 ECT high voltage and one was low voltage on another sensor. None of the error codes were repeated during the 7 hours I worked with the mechanic after more than 30 starts of the engine. Problem condition of hunting and surging exists on every start and when the engine is cold and warm. I believe the error codes were caused by the troubleshooting by the mechanic (plugging and unplugging connections) and may not be a real lead to solving the problem.

[gofast24]

Thanks Jeff, I think you will finally get this figured out! Still not sure why both engines exhibited the same problems! Has to be something simple that hasnt been diagnosed yet?

[robing]

Wonder if you guys tried spraying carb cleaner on intake manifold, hoses etc. While it was running to try and see if it leaks. You mentioned low vacuum, could be a bad gasket or hose etc?

[robing]

"Low fuel pressure at 0 vacuum "?
Would it even run at 0 vacuum?

[gofast24]

Good idea about the carb cleaner on the throttle body and intake manifold connection to the heads. In the day we used diesel fuel, fairly safe
I dont think there are any hoses between the throttle body and the intake manifold but who knows what has changed over the years? Could also check the CVV's (crankcase ventilation valves) which would go from the rocker covers to slightly down stream of the TB? They could be allowing too much air/vapors into the intake and screw up the IAC valves? In my earlier life on a carbureted engine the CVV hose was connected to a "tube" just in front of the flame arrestor but that wouldn't be the case in Jeff's situation. i still believe that there is something simple causing the problem, especially with both engines exhibiting the the same problem?

[JNelson90]

Weekend updates; I got new throttle body gaskets so I could swap the port and starboard throttle bodies to see if that made a difference. I noticed that they had reused the old throttle body gasket (had some red paint on it since I had installed and painted the brand new throttle bodies on both engines in 2014). I was really optimistic but it did not fix the hunting and surging problem.

Clarification; the problem is only on on the port engine with the new longblock. I originally had the issue in 2014 with both engines hunting and surging which is why I replaced both throttle bodies and that basically fixed the issues. The hunting back in 2014 on both engines was not as bad as the problem I have today with the port engine. They still hunt a bit but only 100 or 200 RPM after I installed the new throttle bodies. The new longblock/port engine hunts from about 400 RPM up to 1400 RPM and seems to almost stall, but it doesn't.

One new point; the port engine seems to idle perfectly (better than the starboard engine) for the first 1 or 2 minutes right at the 700 RPM mark but only when cold. Then the hunting starts, small at first and continuing to grow in range of RPM. I was watching with my code reader to confirm IAT (Intake Air Temperature) and ECT (Engine Coolant Temperature) temperatures. The manual indicates they must be within 5 degrees of each other when the engine is cold; they were only 2 degrees off. After the 1-2 minutes of good idling the ECT temp only went up a degree or two and then the hunting started.

Other clarification points; for vacuum - there is one line from the intake manifold to the fuel cell pressure regulator. The fuel cell has been replaced the the vacuum line swapped with the starboard engine.

Lastly, I did check the torque on the intake manifold and the bolts were very loose. I went through the 3 stages of torque using the proper torque bolt order - thought this would help but it did not as well. No changes at all. I think that I have exhausted everything that I can do to fix the problem.

[gofast24]

Dont give up yet!
Call or better yet write a letter or e mail US VP corporate and tell them your problem and that none of their factory authorized dealers can fix it! Your problem not being able to be resolved by a authorized VP mechanic will creating a lot of negative press especially here on the ROF. Was your long block replacement engine a factory rebuild? If so, that maybe will get VP to do something to resolve your problem! I have had a similar problem with 2X Merc factory re man 502 about 10 years ago, finally Merc sent a brand new engine to a specific dealer here and they replaced the 2nd re man engine with new and the problem resolved! Long story, dont need to get into the specifics here.

[JNelson90]

Update; I drove the boat down to another marina with certified Volvo Penta mechanics on Wednesday. It drove well, idled perfectly while in gear but surged when in neutral (port engine). It had been over 10 months since I last was able to drive the boat out of my slip and that was totally exhilarating. I can't tell you how much I had missed being able to drive the boat.

The VP certified mechanics started working on the boat yesterday and I have not heard anything back yet. I did speak in detail about the issues with both the service manager and lead Volvo Penta mechanic. They felt like we had already addressed the majority of the possible causes for the hunting so I suspect it may not be an easy fix for them. I will let you know once I hear back from them and hope to get back to a fully working boat before too long.

[gofast24]

When you put the port engine in gear that will drop the engine RPM enough for the ECU to detect and the ECU should compensate by using the IAC valve to bypass a little more air around the throttle plate into the intake manifold and also tell the injectors to supply a "little" more fuel to maintain the 700 or so engine RPM with the small load from the prop in gear, or in your case visa versa with surging in neutral. So as of now your only problem is the port engine? Sounds like the throttle plate needs to be checked for the correct position at the idle stop (usually a stop screw adjustment)

Good luck and be sure to advise what is found to be causing the problem!

[JNelson90]

Thanks for your insight once again. I believe the throttle body on my engines does not have a user settable screw for the throttle plate. The ECU controls the idle speed and the throttle position sensor tells the ECU when the operator wants more RPM's. The ECU is set at 700 RPM for idle. I have tried replacing both the throttle body and throttle position sensor but to no avail. The new Volvo Penta certified techs are working on my engine (started last Thursday). I hope to have a solution to share with you all once I my boat is finally fixed (I hope).

Clarification; the problem is only on on the port engine with the new longblock. I originally had the issue in 2014 with both engines hunting and surging which is why I replaced both throttle bodies and that basically fixed the issues. The hunting back in 2014 on both engines was not as bad as the problem I have today with the port engine. They still hunt a bit but only 100 or 200 RPM after I installed the new throttle bodies. The new longblock/port engine hunts from about 400 RPM up to 1400 RPM and seems to almost stall, but it doesn't.

[gofast24]

Jeff, thanks for the update!
My latest thoughts are ask the folks you bought the long block engine (VP re man?) from ($$$) how they intend to resolve this idle problem and who is responsible for the cost to make it correct! If it is actually a VP re man long block and installed by a VP authorized dealer time to write VP corporate a nice letter indicating your situation. About 12 years ago I went thru 2X Merc factory re maned 502 engines in less then a month. Ended up I found the dealer that installed the long blocks reversed the oil lines from the engine block to the remote filter header. With a filter with a anti drain back valve that basically blocked any oil getting back to the engines oil circuit or thru the oil cooler as well. Merc bellied up to the bar and sent me brand new 502 long block, paid for the R + R, and had another authorized dealer install it, no more problems since (boat long gone though). The engine they sent was one of the last 2 new 502's they had left in their inventory!
Good luck, this is getting interesting (for me, probably not you?)

[gofast24]

Jeff, time for an update?

[JNelson90]

The boat has been at the Marina with the certified Volvo Penta mechanics since Wednesday May 30th. I spoke with someone on Tuesday June 5th and they thought that some parts were on order with VP and I should have my boat by that weekend. I called back that Thursday and was told by another person that they were waiting on information from Volvo Penta and that they still did not have a solution. I called again this morning and was told that multiple mechanics have been working on my engine all morning but no additional details. I am anxious to get it fix and to find out what the problem was. This seems to be the never ending service issue (started last August). I will let you know when / if they fix it.

[Muddy Blues]

Wondering if a simple vacuum leak is the culprit here?

On a car I had years ago, the coolant temp sensor went bad - it sent a -40F reading to the ECU, causing the engine to run super rich. Does not take much to mess up these EFI motors.

Hope you get this sorted quickly.

Keep us posted.