Engine running rough, shutting off

[mia248vista]

Hello everyone I am new to this board! Unfortunately my first post comes with a problem.

I have an 03 Volvo Penta 5.0Gxi-b with a DP-S drive.

I have been having issues of late with my engine. The problem is as follows, I came home one day after a weekend of fun and use of the boat while when doing my normal cleaning and flushing routine the engine shut off on me. After half a dozen attempts to start it I gave up and finished cleaning. 1 hour later the boat started up just fine however since then the boat has been running rough. It was more apparent the higher in RPMs I went.

Checked plugs and they were black. The local Volvo Penta shop said is a result of running a bit rich but there was no sign of water.

I noticed that there was a bit of oil on the flame arrestor and a check of the dipstick showed there was an overfill of oil in the crankcase. I went ahead and cleaned out the flame arrestor and throttle body. Adjusted the oil level. I also did a compression test which resulted in 120-150 on all cylinders. While doing the compression test I also went ahead and put new plugs. After putting this all together the engine was very difficult to get started. After getting it running it is rougher than before all the cleaning and plug replacement. It is also shutting down while in idle and requires me to give it a little gas to keep it running if not it will shutdown. I feel like I am going backwards here!!!

Any thoughts as to what is going on here? Recommended next steps?

 

[Don S]

Re: Engine running rough, shutting off

First of all, check the basics. Remove the fuel filter and empty it and see if there is water in it. If so, how much?
When was the last time the cap and rotor were replaced?
Do a wiggle test on EVERY wire connection on the engine. While it is running. including battery cables, main harness connector and all sensors.

 

[mia248vista]

Re: Engine running rough, shutting off

First of all, check the basics. Remove the fuel filter and empty it and see if there is water in it. If so, how much?
When was the last time the cap and rotor were replaced?
Do a wiggle test on EVERY wire connection on the engine. While it is running. including battery cables, main harness connector and all sensors.

Thank you Don.

I will check the fuel filter and wiggle test tomorrow but the rotor and cap were replaced May of 05 (2 years old). Is it worth replacing at this point while doing my wiggle test and fuel filter check? Also when I remove the fuel filter and check for water can i use that filter again or do I need a new one? The fuel filter is 2 months old.

 

[mia248vista]

Re: Engine running rough, shutting off

Pulled the fuel filter and fuel was clean, no water.

The rotor and cap did not look so great so I went ahead and replaced those. The good news is she starts up now no problem and doesn't need gas to keep running.

The bad news is she is still running quite rough at idle and more apparent as i increase rpms. I did a wiggle test while the engine was running but didn't see anything that affected performance.

Don or anyone that can help me what would be my next step here?

 

[mia248vista]

Re: Engine running rough, shutting off

anyone?

 

[mia248vista]

Re: Engine running rough, shutting off

UPDATE:

I was able to get to the boat today in between the monsoons that have been falling here.

When I got there the boat would not start. Cranking and turning over just fine but would not start.

I went ahead and installed the new plug wires that finally came in.

2 interesting things...

1. the cable on cylinder 8 had a small tear in it which i only saw when i pulled the old cables out.

2. the volvo penta cables that go with this engine which i bought at my VP dealer were different in size 7mm vs 8mm.

After installing the cables I was hoping based on the 2 things above she would fire right up.

Unfortunately she did not. Then to add to my problems a new storm came over and I had to stop my troubleshooting.

One thing I have noticed is that water has been getting into the bilge during the episodes I have been having problems with it starting

washing the boat (just hosing off the deck) the first post 5/26
cleaned the bilge after doing plugs and compression check 6/10
rain all day 6/17 (today)

The engine room has been covered as usual and the plastic engine cover over the engine and electrical components. Not sure if it is related or not but I am starting to believe this is not coincidence.

If anyone has any further ideas on this please share. Tomorrow I will check ignition and fuel again (just in case) and then go to testing the sensors.

 

[Maclin]

Re: Engine running rough, shutting off

Since you suspect moisture you might check the big connector plug that connects the dash wiring harness to the engine wiring. If it can get wet then I suppose the connections could have begun corroding or any exposed wire could have begun wicking up moisture and corroding. Mine is a lot older than yours (1991) and the connector runs vertically and caught water as the Marina moved it around waiting for the previous owner to pay up the slip fees. When I bought it 2 years ago as a repo the Marina shop guys had to replace some of the wiring there to get it to run good and pass the sea trial.

If it is easy to get to and unplug and re-plug without causing more problems then I would do that, unplug and plug it back in a few times, it might clean up the connections enough to clear up the issue.

 

[mia248vista]

Re: Engine running rough, shutting off

Maclin,

Would that harness keep the boat from starting? I always assumed it only sent signals to the gauges.

Thanks for the suggestion!

 

[Don S]

Re: Engine running rough, shutting off

Do you have spark when trying to start? Here is a big question, and with EFI engine a big requierment. Is it turning over fast enough. A low battery will not turn an EFI engine fast enough and the voltage drop is too much for the ECM to let it start.
If it is turning fast enough, you still need to see if you have spark, but you also need to confirm fuel pump pressuer. After that, you need a scan tool to see what is happening. You also MUST have a manual for about any of it.

 

[mia248vista]

Re: Engine running rough, shutting off

Do you have spark when trying to start?

Yes.

Here is a big question, and with EFI engine a big requierment. Is it turning over fast enough. A low battery will not turn an EFI engine fast enough and the voltage drop is too much for the ECM to let it start.

It is turning over to the point the rpm gauge goes to 400 RPM.

If it is turning fast enough, you still need to see if you have spark, but you also need to confirm fuel pump pressuer.

Spark is ok.

I have not checked pressure for the fuel I will look into that.

After that, you need a scan tool to see what is happening.

I have a scan tool but all i get are 12s (system ok, no codes stored).

You also MUST have a manual for about any of it.

I have the Seloc Manual.

 

[Maclin]

Re: Engine running rough, shutting off

Mia,

I have no expert experience with the wiring on your boat and did not mean to distract or detract, I was just spitballing some, thinking of moisture related issues and simple things to check or try. Mine is the older and simpler design and the integrity of that plug definitely had an effect on the ignition components. When you mentioned moisture as a potential factor I thought I would relay my experience. If your problem is moisture related then it could be other connections somewhere also, not just the harness connections. Just keeping the juices flowing here...

 

[mia248vista]

Re: Engine running rough, shutting off

Thank Maclin,

I really appreciate it! No distraction at all. I am somewhat lost with the issue right now but the more I investigate the more I am quickly learning on how to diagnose and how my EFI works. keep the ideas coming!

 

[flabum]

Re: Engine running rough, shutting off

Check your fuel pressure. High fuel pressure will cause it to be hard starting, run rich and rough. Low fuel pressure will let it start then die. No fuel pressure will not let it start.


If you have high fuel pressure, then the fuel regulator is the likely culprit.

 

[mia248vista]

Re: Engine running rough, shutting off

I was able to get a fuel gauge on the fuel rail. I got 60psi. I can't find in my manual if this is in range.

While doing this i also went ahead and did a few more things.

Inspected cap and rotor for water. Nothing inside.
Took off the ignition coil for inspection. Did not look great but delivered spark.
Disconnected, inspected and cleaned the main wiring harness per Maclin's recommendation

While doing this i had the main wiring harness outside of its bracket, and i just had the ignition coil sitting on the block.

Turned the key and it turned on just fine! Repeated that 3x. Told the admiral to get dinner ready while I put the wire harness and IC in there proper place.

After seating the harness and ignition coil in their proper place...
Turned the key and.........................the thing would NOT start. Same behavior. You hear the engine cough as you turn the starter but it just won't go.

I am starting to think it is that main harness or ignition coil. Unfortunately I could not go back to the configuration with the harness and IC not in their proper place.

What do you guys think?

 

[Don S]

Re: Engine running rough, shutting off

50 to 60 psi is book value for the HP pump, 8+-4 psi for the LP pump.

Have you tried moving the throttle to the WOT position and trying to start. That is the "Clear Flood" mode.

 

[newport dave]

Re: Engine running rough, shutting off

I've seen a similar thing with a Delco EST coil, where the engine would not run when the coil was mounted but would run when the coil was not bolted down. This was due to the coil winding being shorted to the mounting bracket. Check the coil connections for continuity to ground.

 

[mia248vista]

Re: Engine running rough, shutting off

50 to 60 psi is book value for the HP pump, 8+-4 psi for the LP pump.

Have you tried moving the throttle to the WOT position and trying to start. That is the "Clear Flood" mode.

I have used the "clear flood" but that doesn't help me in this situation.

I've seen a similar thing with a Delco EST coil, where the engine would not run when the coil was mounted but would run when the coil was not bolted down. This was due to the coil winding being shorted to the mounting bracket. Check the coil connections for continuity to ground.

I will give this a try in about 15 mins. I will provide update after. Thanks for sticking with me!

 

[mia248vista]

Re: Engine running rough, shutting off

UPDATE!

tried to start the boat, nothing as expected

disconnected the 2 mounting bolts for the coil and she started up. Is my coil bad? Do I need to replace it?

 

[Maclin]

Re: Engine running rough, shutting off

(me again!) That coil squeezing scenario that newport dave described sounds most plausible now....you seem to have eliminated the harness connector.

I would go get another coil if it was up to me.

 

[newport dave]

Re: Engine running rough, shutting off

Is my coil bad? Do I need to replace it?

Sure looks that way to me.