Help! Please help! 5.7 gxi-d mpi engine issue?

[Jeepen]

I have a 2004 Fourwinns Funship 26' Boat with a 5.7 GXI-D Multi Port injection engine with Volvo Penta DuoProp outdrive. I am ready to go nuts and Broke trying to fix this thing. Sooo Very frustrated!!!! If someone could help me or lead me in the right direction I would pay them, just need my boat back.

Little history-I have owned the boat since new and never had any major issue's with it. It has 341 hours on it. Last year the riser gasket went bad and I sucked some water into the cylinders. Not enough to hydro lock. But enough when I pulled it out of the water and stored it for a month, it had built up rust on the valve seats causing very low compression. I installed new vortec heads and since put about 40 hours on the engine.

Now to my common problems. We had the boat on the lake WOT for about an hour, boat was running great. We pulled up on a beach and the boat sat for about an hour. When we got ready to leave it started right up and we idled out a ways. When I started to accelerate about 1500 RPM it started to miss, loose power, popping and backfire. So I stopped shut it down looked it over could not see anything obvious. So I started it, revved it up to blow it out and was able to get planed out. But noticed a big decrease in power. We got to the boat ramp pulled up to the beach deflated all the toys cleaned up the boat and got ready to load it. Well now it barely started, would not rev up at all and had to pull it on trailer.
I am a diesel mechanic and pretty savvy around most engines. But the boat world is just that it is a boat world. So here is what I have done for trouble shooting.

Compression test first thing! All 8 cylinders were at 150 psi-Assuming no compression or valve issues!

Fuel pump test showed that the low psi pump only had 2psi and High psi had 50. I thought Great, this is it! So installed new pump, and Regulator. Performed psi testing after install and the low pump showed 10 psi and high 55psi. Now the boat starts good and sound great hooked to the hose. So head to the lake for water test. Boat starts fine, idles up great engage throttle to1200 RPMs and falls on its face knocking, popping and backfiring. Back to the shop.

Now things point towards ignition issue. So I replace the following! New Cap, rotor, plugs & wires. Starts fine runs and revs good on the garden hose. Lake test same thing Knock, pop over 1200 RPMs. So Now I spend 600.00 on Rinda Technologies TechMate Pro. Plug it in and it shows no issues, everything is normal??????? Uggg!

Now I take extra steps towards possible ignition issues. Replace Cam position sensor in distributor, new coil, new module, cleaned MAP sensor and inspected all wiring. Headed to the lake and same thing! The only thing I have not done is change the crank position sensor, but it starts so good I can’t imagine that being it.

Also on the fuel system, I added new suction hose from the tank, verified no issue’s with the breather, added an inline clear filter that shows there is no restrictions or debris.

Someone out there has had to have this problem, any insight would be very much appreciated. I am willing to pay someone to help me solve this issue missing my boat very much!

 

[alldodge]

Rinda is a good scanner but the MEFI is not that great and providing all info desired.

Is the fuel pressure staying at the levels (10 and 55) as you throttle up?

Check for 5V at the injectors

 

[tpenfield]

MPI engines really need the full Rinda Diacom software to troubleshoot. $600 should have gotten you the Diacom and not just the TechMate.

Just about every engine runs great on the garden hose, so don't use that as a yardstick.

You really want the Diacom hooked to the engine at the lake and recording the data. Then you (or we) can look at it to see what jumps out as the problem.

 

[Jeepen]

Tpenfield? - The diacom software you are talking about, can it be purchased for my scanner? I have the techmate pro.

AllDodge - I did keep the pressure gauge hooked to the high side while I was throttling up at the lake. The gauge started to bounce pretty erratic at full throttle. Could not tell you what it was bouncing between. I replaced the suction hose from the tank to the low side of pump and verified the breather is clear. Also zero debree in the clear filter as well as the fuel regulator.

I really appreciate the reply's! Getting super desperate and no repair shops around here to fall back on.

 

[alldodge]

The diacom software runs on a laptop and is used instead of the techmate. With the techmate you have watch individual items and remember them, and the diacom will record everything so it can be looked at later. The diacom is also sold by Rinda

gauge started to bounce pretty erratic at full throttle

With it bouncing, this could be an electrical issue with powering the pump like a connection (power or ground) or fuel pump relay breaking connection. It can also be an issue with the fuel pressure regulator, but most times the regulator will change pressure more smoothly and not bounce

Look close at the grounds on the ECM and the relays. Both the fuel pressure and main power are the same type, and your start relay should also be same type, so they can be swapped

 

[Jeepen]

Also one other thing. During acceleration in the water I would have to say its more a popping through the intake verses backfire. While running on the hose it does not smoke or smell of rich fuel.

 

[Jeepen]

While running the boat in the water in any throttle position should the high side psi gauge maintain? Or should it drop slightly due to fuel consumption?

 

[alldodge]

The spec on the GXi pump is 50 to 60 psi and should not go below that. Its ok if it drops a little from idle to WOT but still should not go below 50 psi, and at no time should it bounce. With the motor popping, this is the motor running lean.

 

[Jeepen]

Alldodge- I will focus a little more on my fuel system. Im thinking about pulling the injector rail and injectors and cleaning them. Is there a flow test of some sort I can use for the HP pump side. If I remember right my new techmate Pro gives me some fuel info. I will try to run as many test functions as possible and get back to you. Thanks

 

[alldodge]

Checking fuel rail is good, but really don't see that as causing your issue. The bounce of the fuel gauge, tells me more the pump is turning off/on more then the fuel path. Just reading what I think your saying

 

[89retta]

"

We had the boat on the lake WOT for about an hour ". Do you always run your boat like this ? I have a feeling running like this might have something to do with your problem​

 

[Jeepen]

89retta - I think I understand your comment. When I say WOT I actually mean I’m running at a comfortable speed and RPM. Probably around 3800 to 4000. This motor is the GXI that was capable of 4800 to 5000. But I take care of my equipment and if anything I over maintain. Cruising down the lake for hours on end is what they were built for. Repair suggestions would help tremendously if you have any?

 

[DouglasW]

If $600, or even $195 is a bit out of your budget, I have written pc scan programs for MEFI2, 3 and 4. They are free with no ads or other annoyances. If you have the 555 ECM, then this won't work. But to use my pc app you would need to make a cable for about $30. Any of them should give you all the data that the ECM provides.

 

[Jeepen]

DouglasW - I’m very interested in your program. Mine has the MEFI 4. Would love to know how to get the cable and the program. I already bought the techmate pro scanner but it’s not proving to be very Benifical. Thank you for your reply.

 

[DouglasW]

See pages 2 and 3 of this topic: https://forums.iboats.com/forum/engi...rotection-mode


In addition to providing screens of live data for engine, status, and trouble codes, it can datalog the whole engine data screen contents in .csv format, You can use a spreadsheet program like Microsoft Excel or OpenOffice to analyze the data in the file or just load it back into the app for playback viewing.

 

[muc]

I would start with the fuel pressure jumping around. First, how much is it changing while the engine is under load and acting up? Are you using a quality gauge that you can trust?

I don't know of any flow tests for the pump, other than if it can maintain rated pressure at W.O.T.
Also pressure should increase 2-4 psi at WOT just like it should increase during testing when you pull the vacuum hose off of the regulator.

If fuel pressure is erratic it will be electrical or more likely air getting in the system.

Buy a new fuel filter. Remove the old one and dump it's contents into a clear container and inspect.
Install the new filter (don't reuse the old one!) making sure there is only one gasket. Hook up your fuel pressure gauge and run the bleed hose to a gas can or your gas tank if the hose reaches. Use your techmate to run the fuel pumps while the bleed is open on the pressure gauge. Do you have any air in the stream of gas? For the electrical side you can rig up jumper wires to power the pumps during testing.

Do you have the Volvo service manuals for your engine? If you post a serial number, I can tell you what one you need.

 

[Jeepen]

Muc - you make some awesome suggestions. Never thought of running through the gauge, I will try that. The pump and filter are new. Also added new suction hose to tank with clear inline filter. Checked regulator, and tank vent. Everything seems fine except for the gauge bouncing. One other thing I have not mentioned is while trying to plain out if you pump the lever it seems to slowly gain momentum. Does not make sense because it’s electronically controlled. Maybe throttle position sensor?

 

[muc]

Get rid of the "clear inline filter" it's not needed and can only cause problems.

How did you check the regulator?

You have a scan tool and you haven't used it to test the TPS?

A scan tool very rarely tells you whats wrong! It's main purpose is to allow you to quickly know whats right.

 

[Scott Danforth]

Not to mention the clear in-line filter is illegal because it will feed a fire

Check the anti siphon fitting and pull your fuel fill cap next time it acts up. If it clears up, then your tank vent is plugged

 

[Jeepen]

The clear inline filter is only for testing purpose's to verify flow and debris, not a permanent fixture.As far as testing the regulator I did not. I replaced it with a new one. The old one I pulled out, had a fine screen, it had a few specs of debri but nothing I would consider alarming. The new Volvo Penta replacement had a clip instead of a screen apparently this was some kind of update. I did try the removal of the gas cap during load test and did not change anything. Plus I have replaced the suction line from tank to pump and verified no issues with the breather. As far as testing the TPS I am trying to figure out how to do it. The scanner numbers don't mean anything to me because I don't have anything to reference yet. Still trying to gather that info. I bought the Seloc Volvo Penta manual but it seems to be useless on some issue's because it covers to wide of spectrum. If there is a test procedure with data that I can use and compare my numbers with please let me know where I can find it.

Last night I checked all my electrical connections to the pump. Everything is testing great with tight connections. I ran some fuel through the relief tube of the psi gauge and it seemed to have very good flow. Both pumps test good with 8 psi on the low side and 56 on the high. I have no way of load testing until this weekend. But I feel like My fuel system is working properly. The open throttle load test will tell more if the gauge goes erratic.

Another test I performed last night with mixed results was the counterbalance test with the Scanner. On my scanner it has a letter for each cyl instead of a number going in sequence of firing order. During this test it seamed like all odd cyl you could hear a definite change in Rpm and even cyl not sure if I heard any change. Also the plugs are new and I pulled them again to do another compression test with a different gauge because my numbers were so close the first time. Well second compression test all 8 cyl 150 psi +/- 1 psi. Seems strange that they are that close. The other thing I noticed is all four plugs on the even cyl were kind of wet like fuel or oil coated. I tested spark off of coil very strong and blue. Tested spark off of each wire strong and blue.

What am missing???? Going Nuts!!!!!! (I REALLY APPRECIATE ALL THE ADVISE AND HELP) I will admit I am learning a lot of important skills that will hopefully help me in my future boating adventures. Its great to have knowledgeable people on this site to bounce ideas.

DOUGLESW - Please get back to me on your program and wire connector. I would love to get this ASAP. I don't mind paying for any help as well. I need to gather as much data as possible so I can get over this herdal.