Volvo penta stalling help

[Tipafew]

Looking for help....I have a 2001 Cobalt 360. Twin VP 8.1 GXI. I have had a problem I have been struggling with for a couple of years now with no luck.

When I first fire the engines cold they fire really quick and stall. Hit the key again and they fire right up and run fine. They both do this exact same thing...... That's not the big problem though.... When I chop the throttles quickly from say 1,000 rpm the motors will quit instantly. They don't do it all the time but always seem to do it while docking which is exciting. Usually it's just one of them but I have had a couple of times lately where they both quit at the same time.
If I slowly ease back the throttles to idle they will run perfect every single time. Of course when a boat in front of you in a channel decides to turn directly in front of you, you tend to chop the throttles really quick which leaves you silently gliding toward them.....

Fuel pumps were rebuilt already due to failure. It did this before then as well so not related to pumps.
I replaced both IAC, but I used AC Delco....... Could that be a factor?
I did aftermarket throttle position sensors as well.
Fuel pressures have been checked and are good.

Boat runs absolutely flawless except for this. I'm so ready to be done with this issue. I would love to get someone to hook it to a computer but that is hard to find. Everyone is swamped.

HELP

 

[alldodge]

The biggest issue is your replacing parts and don't know what the issue is. Don't see an issue using AC Delco parts, if they were actually AC Delco. If you got them for ebay or Rock Auto maybe not (personal experience)

It acts like a IAC issue but both are doing it the same. When boat is idling are the ALT's producing 14.5V?

Aftermarket TPS can be an issue. Need to scan the motor for codes and also watch what its doing. See what all the sensors are reading

 

[Tipafew]

The biggest issue is your replacing parts and don't know what the issue is. Don't see an issue using AC Delco parts, if they were actually AC Delco. If you got them for ebay or Rock Auto maybe not (personal experience)

It acts like a IAC issue but both are doing it the same. When boat is idling are the ALT's producing 14.5V?

Aftermarket TPS can be an issue. Need to scan the motor for codes and also watch what its doing. See what all the sensors are reading

I don't disagree that just throwing parts at something isn't the best method, but I also hate to have the boat spend 3 weeks at a dealer during the season. I wish I could find someone to scan it. I think I looked into buying a scanner before but they were pricey for a VP. Might still be worth it........

Yes, both Alts are producing good 14.5 volts if I test them at the gauge, but the starboard dash gauge has always read closer to 13. That's why I tested them at the alternator before. I assumed it was the gauge at the time but have never actually tested voltage at the back of the gauge....... Might be smart to do.

 

[alldodge]

The gauge can be off, so might not be an issue.
If power at the motors are less then it can be a problem. Are ground cables clean and tight, and any corrosion on starter post and other connections?

The rinda Techmate will cost 500 with the single adapter for your motor. These new motors is a must have to in most cases to even begin

 

[Tipafew]

The gauge can be off, so might not be an issue.
If power at the motors are less then it can be a problem. Are ground cables clean and tight, and any corrosion on starter post and other connections?

The rinda Techmate will cost 500 with the single adapter for your motor. These new motors is a must have to in most cases to even begin

All connections are clean. I will double check voltage again at the starter, but starter is fairly new(problem existed before that so not related)

Are you still classifying my 2001 as "new motors"? Probably referring to anything with a computer I am assuming.

I might spring for the $500. I can always sell it someday if I change boats.

 

[alldodge]

New to me is anything with a computer. No way I'm buying a CAT motor

The Techmate with adapter is good thru current CAT motors, just need different adapters. THe CAT motors require another 300 for adapters, but prior to that their around 50 each based on which ECM/PCM is installed

 

[mvn]

I had a similar situation with a 5.0L mercruiser sterndrive. I learned that all IAC's are not created equally. The only one that would work was a Merc OEM one. No stalling issues since.

Mark

 

[tpenfield]

Without having the computer connected to the engine and recording data when the engines stall, it will be difficult to identify the problem.

Not sure why you need to 'chop' the throttles, particularly around the docks. You probably should be engaging the gears at idle, not needing much more throttle, if any. That might make things a bit easier around the dock until you can figure things out.

The IAC and TPS are basically automotive parts anyway, so as long as they are functioning it should not be the issue.

If you are trying to fix things yourself, you will need at least the TechMate Pro or the full Diacom PC software. The only thing that I would say is that the engine seems to be stalling when the RPM is rapidly reduced. This happens both when the engines originally start - they typically go up to 1,500 RPM and then quickly come down to 700-800 RPM for the warm-up cycle. Same thing happens chopping the throttle.

I'm not sure if there is a known sensor input (or issue) that would cause the engine to stall in those situations. However, by capturing the data with the computer, you could see if the injector pulse is going way down and what other sensor input may be causing it.

 

[Tipafew]

Without having the computer connected to the engine and recording data when the engines stall, it will be difficult to identify the problem.

Not sure why you need to 'chop' the throttles, particularly around the docks. You probably should be engaging the gears at idle, not needing much more throttle, if any. That might make things a bit easier around the dock until you can figure things out.

The IAC and TPS are basically automotive parts anyway, so as long as they are functioning it should not be the issue.

If you are trying to fix things yourself, you will need at least the TechMate Pro or the full Diacom PC software. The only thing that I would say is that the engine seems to be stalling when the RPM is rapidly reduced. This happens both when the engines originally start - they typically go up to 1,500 RPM and then quickly come down to 700-800 RPM for the warm-up cycle. Same thing happens chopping the throttle.

I'm not sure if there is a known sensor input (or issue) that would cause the engine to stall in those situations. However, by capturing the data with the computer, you could see if the injector pulse is going way down and what other sensor input may be causing it.

It’s been situations where maybe coming in slightly faster that ideal so after putting it in reverse I give it just a little throttle. If I return throttles back to idle too quickly it can stall at times.

Yes when it first fires it does a quick Rev up to maybe 1500 rpm then when it quickly comes down its like it just drops right off and quits. Second time I hit the key it will catch itself on the way back down.

 

[alldodge]

It should never just die going to neutral. Something isn't right, unless it has something like a vacuum leak but that would have other issues

Fuel pressure should be 40 psi

 

[Tipafew]

It should never just die going to neutral. Something isn't right, unless it has something like a vacuum leak but that would have other issues

Fuel pressure should be 40 psi

Separate throttles and gear selectors. So it’s not when I’m going into neutral. Just when the throttles are being brought down quickly.

 

[alldodge]

Fuel pressure, TPS and MAP

 

[1000 Islands]

Clean the throttle body bores and plates. Spray a minimal amount of carb cleaner on a rag and wipe as much as you can away. An old toothbrush works well too.

 

[Tipafew]

I bought a Techmate pro. Wondering anyone knows where I can find the correct ranges for everything like the IAC, TPS volts, MAP volts, IAC position, Timing degrees, etc. I searched the web for a while and can't find a thing.

I had no codes at all.

 

[Tipafew]

I have a Seloc manual but it's not at my house currently......maybe they have something in there??

 

[Tipafew]

Did a big boat trip a couple of weeks ago. I ran about 3000 RPM for 4 hours and then pulled into a channel. I backed the throttles down to 1,000 rpm for the channel ride. As I got into the lake I started putting out fenders so I just chopped the throttles from 1000 to idle speed and both engines died instantly. It was like the IAC didn't even try to catch them and bring them down.

 

[Scott Danforth]

I have a Seloc manual but it's not at my house currently......maybe they have something in there??

Seloc manuals are good for knee pads or starting fires. they make better out-house paper than they do manuals

get the factory Volvo Penta suite of manuals for your motor/controls/drives

 

[alldodge]

Ya got a Techmate and there are no codes, good news
What about the other items folks have been asking about?

 

[1000 Islands]

It's just not not simple. There's still some black magic to it. It takes years to be able to look at data w/o codes and make some sound diagnostic determinations. More complicated than getting a scan tool and a book. Have you checked fuel pressure?

I have the VP service and diagnostic manuals. Coming from a 40-year background in automotive repair, don't waste your money. They are poorly written and by the time you order and receive, boating season could be over depending on where you are.

Did you clean the throttle bodies? That's something a DIYer can do if you are careful. Other than that, finding a local marine tech with experience and strong diagnostic skills is where you should focus your energy on.

 

[alldodge]

It's just not not simple. There's still some black magic to it. It takes years to be able to look at data w/o codes and make some sound diagnostic determinations. More complicated than getting a scan tool and a book. Have you checked fuel pressure?

I have the VP service and diagnostic manuals. Coming from a 40-year background in automotive repair, don't waste your money. They are poorly written and by the time you order and receive, boating season could be over depending on where you are.

Did you clean the throttle bodies? That's something a DIYer can do if you are careful. Other than that, finding a local marine tech with experience and strong diagnostic skills is where you should focus your energy on.

Really, you come from 40 years of auto background and a Manufactures manual is not worth the paper its printed on

While there not the greatest, that is way over the top for me