Need someone SMARTer Than Me 5.7 GXI-F Gas Fuel Spark Backfire issue

Joined
Sep 27, 2013
Messages
3
Long story so I'll try to keep this brief and to the point so hopefully someone can shoot me in the right direction.

Boat = 2004 Four Winns 230 Horizon BR
424 Hours
DP-SM
5.7 GXI-F
Was a saltwater boat "desalting" it.

I bought this boat very cheap with some mechanical problems. I fixed all of them except oil kept getting water in it (slowly). Determined it was head gasket since water was in the cylinders 4 and 6. Ended up being small hole in NEW riser that drained in the cylinder and got in the oil. Boat ran well since at WOT and cruising it blew the water right out the exhaust from the small hole. Fixed that problem with new riser, head gaskets, cleaned fuel engine, sensors, painted etc. Looks great.

Got it back together ran great for about 30 minutes on hose. And you all know this story.... Under load on the water it has no power at 2500-3000 rpm, it pops, backfires, surges etc.

I read a lot of forums...it must be the fuel pump and paint particles. Pump is only 3 months old. Took pump apart, 0 paint particles. Took Fuel pressure regulator off and cleaned...some paint particles, took injectors off and cleaned screens...some paint particles. I put it together and ran a bit better but still surging. Fuel pump didn't seem to cavitate like it did before.

I suspect fuel pressure so I ordered a Fuel pressure tester and am waiting for it

Other thoughts or things I may try...
Anti siphon valve not allowing low pressure pump to work correctly...

Fuel tank 3/4 full and the supply hose was disconnected for about 14 days....Could it be as simple as bad fuel? I will be draining It and replacing with fresh.

Brass fitting on inlet of fuel cell... could it be drawing in air with it? I will be removing and putting some Teflon tape to find out.

Could I have messed up the valve adjustment or distributer alignment when engine was apart? Maybe...I went by the book, set to TDC #1 cylinder was up, adjusted all the intake and exhaust valves as listed in manual, rotated engine 360 degrees and adjusted the other valves as stated in the manual. rotated engine a few more times and put the distributor in when engine was TDC on the #1 cylinder and confirmed the rotor was pointing to #1 on the cap. I'm paranoid I made an error on this but I was extremely careful when doing this procedure. I'll double check if the above doesn't help.

I replaced one of the Knock Sensors, and the other is coming in a few days, it was badly corroded but it did work before the teardown.

I did pull one of the plug wires from the connector on the #7 plug but I recrimped it...could this be the issue. I have a new set of wires coming and will find out.

Desparately trying to get this boat done before I winterize it. Don't want to start with a problem in the spring.

Any help is appreciated. As you can see I've thought of several scenarios but will know more in a few days.
I'll update as I troubleshoot.
 

ericga

Petty Officer 1st Class
Joined
Mar 4, 2012
Messages
213
Re: Need someone SMARTer Than Me 5.7 GXI-F Gas Fuel Spark Backfire issue

Check your firing order and timing advance.
 
Joined
Sep 27, 2013
Messages
3
Re: Need someone SMARTer Than Me 5.7 GXI-F Gas Fuel Spark Backfire issue

Update:

I had a few hours so I checked/confirmed the following...

Fuel pickup / anti siphon from tank...OK, Fuel is easily sucked right into the fuel pump. I did the "mouth" test and put a small clear hose on the inlet from the fuel tank so I can see it. (still waiting on the fuel pressure gauge to properly test fuel pressure, arriving tomorrow from Summit)

Voltage at both fuel pumps is 12v and they come on when you turn the ignition for 2 seconds or so....OK

Cleaned the lower fuel pump connector. Makes a good connection now....OK

Spark plug wires were in the correct order as this was the first thing I checked....OK

I started the engine on the hose and let it run for a few minutes then did a quick burst to 25oo rpm, I can tell it still will miss/backfire under load since it was hesitant in that range.

I pulled the plugs to do a compression test...all the plugs looked somewhat normal...medium brown color, no fouling.

A couple of things I noticed...When I pulled the plug wires off (OEM Volvo Penta) They pulled out of the connector when I was grabbing them from the boot. Wondering if they had some bad connections. I was disappointed in the quality of the OEM plug wires right when I saw them. It's a little too late to test them since 4 of them separated from the connector. I have a new set of 8mm wires coming.

When I did the original compression test...I may not have disconnected the plug from the coil. Can this really ruin your coil so it won't operate correctly under load?


Will update more when I do more troubleshooting tomorrow. Thanks for all your help so far.
 
Joined
Sep 27, 2013
Messages
3
Re: Need someone SMARTer Than Me 5.7 GXI-F Gas Fuel Spark Backfire issue

Here is an update...

*Fuel pressure gauge came Pressure held at 15psi from low pressure port and 50psi at high pressure port. Tested on hose up to 2500 rpm

*put new 8mm summit spark plug wires in and confirmed correct order to numbers listed on cap.

*Installed new knock sensor that was corroded. Insured wires were not near spark plug wires.

Still missing when I rev it to 2500 rpm.

Any suggestions? I'm starting to lean towards ignition components, maybe coil.

At least I haven't spent much yet and have a nice new fuel pressure gauge.
 

ericga

Petty Officer 1st Class
Joined
Mar 4, 2012
Messages
213
Re: Need someone SMARTer Than Me 5.7 GXI-F Gas Fuel Spark Backfire issue

Some Gxi models are very sensitive to spark plugs gap. Make sure you have the right plugs and the right gap. Actually I would change them all.

Have you inspected and cleaned your grounds (stud on the back of the engine)?
 

Walt T

Lieutenant
Joined
Mar 16, 2002
Messages
1,369
Re: Need someone SMARTer Than Me 5.7 GXI-F Gas Fuel Spark Backfire issue

This has a distributor with a Module P/N 3858984 inside that may be the problem. Symptoms are classic. Its about 200 bucks and Volvo is out of them all the time. If you have a timing light I suggest clamping it to various plug wires and seeing if the light gets erratic when you rev it up. That can help tell you if it's electrical or fuel. It has a cam sensor too I believe and I've seen those go bad but that usually causes a no start. A knock sensor wont cause a miss/ backfire but can cause low power, but not that low. Try the timing light test see what happens. Coil is possible but quite frankly I see very few go bad.
 
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