Volvo-Penta 5.7 Gi idles at 1800-2000 RPM

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I have a 1995 Monterey 225 BR with the Volvo-Penta 5.7 Gi that I bought last July. After getting it home I found a few things that I needed to fix before getting it on the water, mainly replacing the floor, stringers, motor mounts, transom gimble bearing, u-joints, carpet, lift cylinders bilge pump and billows. That is done now so I can finally focus on using it. I took it out for the first time 2 weeks ago to find out that it wouldn't rev past about 2,000 RPM. I found that the anti-siphon valve was a common culprit so I removed it. Problem solved, it ran great after that. I changed the fuel filter and put Seafoam in the tank to help clean the fuel system. It has all new fuel, the tank was emptied and removed during the floor replacement. I have 2 batteries that have a full fresh charge (just in case that is a question later). Fast forward 1 week of sitting in my barn.

We took the boat out and immediately after getting into the boat my wife informed me that there was something wrong with it. It was idling too high and kept dying. I started the boat and she was correct. It would start fine, idle about 1200 RPM for about 20 seconds then die. It would start right back up and do the same thing. I got it out of the idle only zone and opened it up and it ran like a top as long as it stayed above 2000 rpm. When I stopped it would die. I ran the boat around the lake for about an hour thinking it might be dirt in the fuel system somewhere and wanted to give the new fuel and Seafoam a chance to work. It never made a difference.

A couple of days later I got the chance to work on it at home and with the muffs on I ran the boat in my driveway. It started fine and ran up to about 2000 rpm and stayed there, it didn't die but wouldn't idle down. It will rev up just fine. I have done a ton of online searching and reading over the past few days and am at my wits end so I am finally posting about it. So far I have checked for vacuum leaks with none found, I have replaced the IAC with no change, I have replaced the MAP sensor with no change, I changed the fuel filter again with no change, I have disconnected, checked and reconnected every connector I can find on the engine with no change, I have tried (using the battery isolater switch) running with battery 1, battery 2 and both batteries with no change.

The only thing that makes any difference at all is when I unhook the vacuum hose for the MAP sensor and plug it off completely the boat will idle down to about 900 rpm however when I do this it will not rev up. Another note is that when it is running at 2000 rpm I can unplug the wires to the MAP and it doesn't change, I can also unplug the IAC with no change. Occasionally it will sound like it hiccups and will idle down but watching the injectors when it does this they completely shut off for a second then come right back on, it does not idle down. The motor sounds and runs great it just won't idle down.

When I started removing the floors in the boat I found a lot of the relays laying around the interior, and there is a spare fuel pump in the glove box. This leads me to believe the previous owner had issues with it also. I am fully understanding that the previous owner unloaded this boat on me, however I got it for a good price and still don't have money in it to be upside down, yet. I am what I consider a shade tree mechanic. I only have hand tools, no scan tools, no pressure guages, etc. I know this isn't the best situation but its the one I'm in. I would like to resolve this issue without having to take it somewhere and lose half the season and possibly thousands more than I would to fix it myself. The next part I'm thinking is the ECM. With the research I've done it looks like the culprit but wanted some more information and input on my specific situation before spending that money.

Sorry for the long post, I wanted to give all the info I had so I could get the best help possible. Thank you in advance!

Doug
 

jimmbo

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Poor connection to TPS or bad TPS? Make sure all connections and grounds are good.
You really need to get the Volvo service manuals for that engine. The ECM can store codes, so you might want to retrieve them, that will require some special tools
 

alldodge

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Howdy Doug

Seafoam and snake oil mean the same thing to me

The motor is a 5.7 Gi - what?

The only thing that makes any difference at all is when I unhook the vacuum hose for the MAP sensor and plug it off completely the boat will idle down to about 900 rpm however when I do this it will not rev up.

What vacuum hose is on the MAP? The MAP in most cases is connected directly to the intake manifold. This is why I need the rest of the Gi-and letters
 

tpenfield

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:welcome: Doug,

Aren't fuel injected engines fun :rolleyes:

I just had (still have) a similar issue with my Merc 7.4 MPI. I had to hook up my computer to the engine diagnostic port to see what the issue was. . . .

Without having the computer software to read what is going with the engine, it is pretty much a shell game as far as finding the problem. Usually it is a bad sensor. In addition to the MAP and the IAC, there is the IAT and TPS sensors. Also check the obvious, if you have not, like the throttle linkage not closing all the way.
 

tpenfield

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Probably need to get the exact model # of the engine.

I see that some V-P 5.7's have crankshaft and camshaft position sensors . . .
 
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Thank you for the quick replies and warm welcome! I didn't realize that I had a TPS so I'll check that and the IAT also. I am on duty today so when I get home tomorrow I'll see about getting the remainder of the numbers and the exact model # for the engine. Of all the motorized vehicles I have ever owned I've never wanted to set one on fire more than I do this one! lol It has given me troubles since I picked it up. On the way home from buying it the trailer came off the ball and smashed the back of my truck on the interstate running 65 mph. I should have known right then to put it up for sale! :)

The vacuum hose that runs to my MAP connects to the bottom rear of the throttle body just above the throttle body gasket. It is pulling a good vacuum by feel but I don't have a gauge to put on it.
 

alldodge

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The vacuum hose that runs to my MAP connects to the bottom rear of the throttle body just above the throttle body gasket. It is pulling a good vacuum by feel but I don't have a gauge to put on it.

That is the Positive Crankcase Ventilation (PCV) valve
 
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That is the Positive Crankcase Ventilation (PCV) valve


So I assume it shouldn't be connected to my MAP? Should I also assume that the connection for the MAP is open somewhere? I'll have to check and see if I can find somewhere for it to hook up. Wouldn't the PCV have pressure or nothing at all? This is definitely pulling a strong vacuum. I also have 2 hoses that I thought were the PCV that vent crankcase fumes back up to the spark arrester under the plastic cover.
 

alldodge

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So I assume it shouldn't be connected to my MAP? Should I also assume that the connection for the MAP is open somewhere? I'll have to check and see if I can find somewhere for it to hook up. Wouldn't the PCV have pressure or nothing at all? This is definitely pulling a strong vacuum. I also have 2 hoses that I thought were the PCV that vent crankcase fumes back up to the spark arrester under the plastic cover.

The PVC valve used intake vacuum (strong vacuum) to pull crankcase combustion gases into the intake to be burned. Only thing that keeps me baffled is there are also wires on the connection?

Take some pics and post because some things are not adding up
 
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So I just looked up the system VP uses for their engine model #'s. I don't have my exact numbers but it should start with 5.7 GiPHU or 5.7 GiPNC. I'll get the numbers for sure tomorrow afternoon.

Again I appreciate all the help I can get. I'm not an experienced mechanic by any stretch of the imagination. I can work with my hands and am mechanically inclined but have never spent much time working on engines. My experience has mostly been small engine (4-wheeler), suspension (lift and lowering kits), replacing broken parts, tune-ups, etc. If I ask a question that sounds arrogant then it was lost in typing, I will not be that way, I need all the help I can get.
 
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The part that the hose runs to is definitely a MAP sensor, I replaced it. That doesn't mean that it is hooked up correctly though. I'll take some pictures tomorrow and post them up. Who knows what happened to this thing before I got it. It may have hoses and wires hooked up in the wrong spots all over the place.
 
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This picture looks really similar to my engine. You can see the 2 hoses running up to the spark arrester, the ECM sitting across the front of the throttle body, the MAP sensor is on our left of the ECU with the wires running into the left side of it and the hose runs off the back of it.
 

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alldodge

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I think you do have a vacuum leak and its probably a pretty good size one. I'm still puzzled about a hose on the MAP and look forward to the pics
 

tpenfield

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FWIW - I did see a parts diagram (somewhere) that showed a tube that connected the nipple of the MAP senor to the intake manifold. Just can't seem to find it now. It would make sense if they were using the common GM MAP sensor without a large intake plenum.

Anyway, you may have to get the computer diagnostics, or at least a code reader on the engine. The engine controller in the picture looks like the MEFI-1 :noidea: figuring it is a 1995 model . . .
 

tpenfield

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Sort of looks like the GM MAP sensor . . . but not attached to the intake manifold/plenum . . .

image_265841.jpeg
 
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Sorry guys, I didn't have time to work on the boat today. TPENFIELD you are correct that it is a GM MAP sensor. I have asked a few friends that I saw today about local people who might have a diagnostic computer for these boats so I have some feelers out. After getting some input from you guys I am thinking that is the best route for me to take but I'm not going to just give up and quit working on it myself. If I find someone else to look at it before I figure it out then I'll take it to them but until then I'm still going to plug away at it. I will try to get the pictures tomorrow morning of the MAP sensor and where it hooks up to on the back of the throttle body. Thanks for the continued replies, I appreciate your help!
 
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If this is a double post please forgive me. I haven't had time to work on the boat today but hopefully tomorrow I will have time to go take the pictures and get the numbers needed to make sense of my problem.

tpendield you are correct in the fact that it is a GM MAP sensor. It is currently hooked to a port on the back of the throttle body whether it is supposed to be or not. I was hoping to get it figured out and fixed before this weekend so we could take it with us camping but that wasn't the case. I will be gone camping this weekend so if I don't get pics and numbers posted up tomorrow it will be tuesday before I can get back to it.

I really do appreciate the help with this. I have reached out to some friends looking for someone local that has a diagnostic computer that can read this boat. I won't quit working on it myself but when I find someone to work on it I will take it to them.

I do appreciate all the help in attempting to diagnose the problem and hope to fix it myself before having to take it to someone else.

Doug
 
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Ok, I tried unhook in the TPS, no change, plugged the TPS back in, no change. Checked for lose power and ground wires, none found. Sprayed carb cleaner all over the gaskets, manifold and TB looking for leaks, none found. Took some pictures, added below.
 

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alldodge

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Need to get a code reader on the motor. If it was a Merc I could tell you how to build one, but with being a VP I'm not sure. Does the VP have a 10 pin connector like this?

DLC connector.jpg
 
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I'll take a picture of the connector tomorrow and count the pins. The connector looks similar to that but I'm not sure on the number of pins on it. The connector is on the top of the engine just in front of the throttle body. I've had it disconnected a few times now swapping out the MAP sensor.
 
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