Help with excessive fuel consumption 4.3gxi-ef

[monster1]

I've noticed my boat is getting terrible mileage. It's a 2101 striper with Volvo 4.3gxi-ef engine. The engine runs great. It doesn't miss and runs smooth throughout the rpm range but I'm getting about half the mileage I did when the boat was new ten years ago. Has relatively low hours and the boat sat for a few years in the driveway only being started every few months. The fuel went stale and the fuel system gummed up slightly a few years ago. The mechanic put fuel system treatment in the tank and topped off with fresh gas. I've ran the hell out of the boat since then always treating the fuel with marine stabil and keeping the engine tuned and fluids changed. One plug wires are original, but three years ago changed out the plugs, cap and rotor. I haven't done anything since except for a fuel filter and yearly oil change since the engine is running well. I figured it didn't need a tune up if it's running like a top. Should I replace all the tune up parts with new anyway? Anyone have ideas of what can be causing my fuel consumption issue?

Thanks

 

[alldodge]

Can you pull the plugs and see what they look like? If it's running rich they should be black, but if they are tan your good.

 

[Tail_Gunner]

Define excessive 4.3 marine engine's are not the most economical engine out there.

 

[fhhuber]

If something is going on, I would first suspect the carb and it should show with black, sooty plugs.

You could also run it at night with the engine hatch open looking for the blue arcs... That would indicate time to change plug wires. High voltage ignitions can arc through the insulation if its degraded even if it looks good.

 

[bruceb58]

So what kind of mileage are you getting? How are you measuring mileage? Tell us more about the size of your boat

 

[monster1]

Its a 2101 striper cuddy cabin. I was averaging about 2 mpg when new. I did a run from long beach to East end Catalina last month under decent conditions and burned through the entire tank. Got less than 1mpg on that run. I'll check the plugs and advise.

 

[monster1]

No Title

Here you go. All the plugs are the same. Notice the oil around the threads of the plug. Every plug is like that. I don't see any oil outside the head leaking onto the plug though. Everything is clean. I'll also add that before my last ousting, I pulled the fuel regulator and cleaned the screen which was caked with paint flakes thanks to the old fuel pump which was painted on the inside. Since cleaning the screen and reinstalling, the boat seemed to run even better. Btw, the plugs are AC Delco 19256067's.

 

[alldodge]

No VP expert but plugs look a bit cold on the heat range. From what I can see in the pic appears you have NGK plugs ITR4A (something) which would be Iridium and VP says to use 3858997 and NGK does not have a cross to the plug number

 

[bruceb58]

Problem is you need to do a plug read after you are traveling at cruising speed, turning the engine off and then doing your plug read. Those look fine but I question the plugs you have in there like Dodge says. They are definitely NGK plugs.

 

[monster1]

Thank you for the help guys. I sincerely appreciate it. But unless AC Delco and NGK make them same plug, these are Delco. It's marked right on the plug. If I remember correctly, I took the factory plugs to Napa and they cross referenced these plugs. Maybe they are the incorrect heat range? Sounds like I should probably stick another set of factory plugs in it.

 

[bruceb58]

Show a picture of the porcelain part of the plug. That portion of the part number you can see in the picture is a NGK part number.

 

[alldodge]

Delco Go Figure, I zoomed in and can see ITR4A15. Suggest checking the gap on the plugs as well

 

[bruceb58]

Delco Go Figure, I zoomed in and can see ITR4A15.

Yeah..that is basically an AC41-101 so that is correct.

 

[alldodge]

Yeah..that is basically an AC41-101 so that is correct.

Does it equate to 3858997 ?

Merc is using AC 41-993

 

[bruceb58]

Does it equate to 3858997 ?

Merc is using AC 41-993

I saw somewhere that Merc also uses the AC41-101 plug in 4.3L. I read where the AC41-101 is just a newer number.

I would have to research the Volvo equivalent.

 

[alldodge]

Maybe FUNTIMES is needed for this because I could be looking this up wrong. But... according to mercruiserparts it shows 0W650000 to 1A063239 and up use the 41-993.

 

[monster1]

I'll try to post a pic of the side of the plug later. I'm having a hard time getting the pic to resize. It won't download.

 

[alldodge]

Try this method

 

[monster1]

No Title

These are the only two pics I took of the plugs today. Hope this will suffice in the identification. I called our local shop. They aren't a vp dealer but are very knowledgeable. I gave them my year and engine model and they cross referenced an NGK plug modelBTR-6EFS s equivalent. I'm tempted to buy these instead of the factory plug at 25 bucks instead of 65.

 

[alldodge]

You could try them (IBTR-6EFS) but I don't know if they cross or not. VP parts are through the roof and folks still buy them, guess its a VP kind of thing, I don't understand because I don't own one. The worst thing that may happen is bad fuel economy.