Pursuit 2260 w/ 4.3 I/O WOT Issue

M

mainestig

Cadet
Joined
May 14, 2022
Messages
6
My new to me '99 Pursuit 2260 actually drops a couple mph when you give it the last bit of throttle to 100% wot. Is there any fuel filters, or fuel screens or something that would limit flow at wide open throttle (wot)? It is a throttle body fuel injected 4.3 V6.

Note: It runs great otherwise. but getting beyond 4k rpm and 34 mph is tough.
 
alldodge

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,757
Thanks
MEFI-1, EST Ignition, TBI
Here is your motor parts breakdown
https://www.mercruiserparts.com/4-3l-efi-gen-tbi-gm-262-v-6-0l01200

My thought is there may be a fuel pressure problem from a weak pump or clogged fuel system. Might also be timing, but it runs good until it starts running out of gas
Fuel pressure should be 30 PSI
Fuel filter canister (looks like oil filter) would be on the starboard side

Remove the fuel filter and pour the contents into a clear container, jar maybe. You want to see if there is anything in there except clean gas

Put new fuel filter back on. May need to fill it with clean gas prior to install. Do put a thin coat of oil on the rubber gasket
https://www.mercruiserparts.com/bam/subassembly/31496/2692/150
 
M

mainestig

Cadet
Joined
May 14, 2022
Messages
6
alldodge said:
Thanks
MEFI-1, EST Ignition, TBI
Here is your motor parts breakdown
https://www.mercruiserparts.com/4-3l-efi-gen-tbi-gm-262-v-6-0l01200

My thought is there may be a fuel pressure problem from a weak pump or clogged fuel system. Might also be timing, but it runs good until it starts running out of gas
Fuel pressure should be 30 PSI
Fuel filter canister (looks like oil filter) would be on the starboard side

Remove the fuel filter and pour the contents into a clear container, jar maybe. You want to see if there is anything in there except clean gas

Put new fuel filter back on. May need to fill it with clean gas prior to install. Do put a thin coat of oil on the rubber gasket
https://www.mercruiserparts.com/bam/subassembly/31496/2692/150
Click to expand...
I purchased the boat last fall and used it once before putting it away for the winter.

I installed a new fuel filter (old filter didn't have any water or debris in it) and last sunday was my first use of the boat. I went ~30 miles. It runs great just sort of falls on it's face at wot.

Can I add an inline fuel pressure guage or somehow read what the pressure is?
 
M

mainestig

Cadet
Joined
May 14, 2022
Messages
6
alldodge said:
Two ways to test pressure.
Can get Merc fitting 91-806901 buy removing the fuel line at the TB.
View attachment 361484
On the opposite side of where the fuel line connects will be a plug. Remove the plug (item 3) and find a adapter (don't know the thread) to connect gauge
https://www.mercruiserparts.com/bam/subassembly/31496/2692/170
Click to expand...
I am going to do this. Thank you so very much!

What stinks is if I need a new fuel pump. I pulled the floor hatch (which was a huge PIA) to inspect the gas tank for corrosion / leaks. I reinstalled it and used marine caulking to seal the floor (just like oem was).
 
alldodge

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,757
mainestig said:
I am going to do this. Thank you so very much!

What stinks is if I need a new fuel pump. I pulled the floor hatch (which was a huge PIA) to inspect the gas tank for corrosion / leaks. I reinstalled it and used marine caulking to seal the floor (just like oem was).
Click to expand...
Depending on access it could be better or worst. Your fuel pump is under the port side of the motor and behind the motor mount. Its in a black plastic box.

The antisiphon valve which connects directly to the fuel tank and has a barbed end which the rubber fuel line connects to. It's a spring loaded valve and if sticking can also cause the issue. So if pressure is up to 30 and stays there until high rpms on the water, the valve could be the issue
 

Attachments

  • anti siphon valve.png
    anti siphon valve.png
    172.9 KB · Views: 0
M

mainestig

Cadet
Joined
May 14, 2022
Messages
6
alldodge said:
Depending on access it could be better or worst. Your fuel pump is under the port side of the motor and behind the motor mount. Its in a black plastic box.

The antisiphon valve which connects directly to the fuel tank and has a barbed end which the rubber fuel line connects to. It's a spring loaded valve and if sticking can also cause the issue. So if pressure is up to 30 and stays there until high rpms on the water, the valve could be the issue
Click to expand...
I will report back. Thank you so much!
 
M

mainestig

Cadet
Joined
May 14, 2022
Messages
6
mainestig said:
I will report back. Thank you so much!
Click to expand...
Reporting back. Been a long summer. Boat ended up breaking down. It took me most of August to get it running again.

The issue I had when the boat broke down was electrical. The engine died and wouldn't start anymore. Initially it was all the 10-pin wire harness's fault (worn out?). I deleted the 10-pin connector and soldered all wires. I did a sea trial and it ran but 1/2 throttle it would die.

I replaced the coil pack and did another sea trial only to have the same issue at 1/2 throttle.

At this point I decided it was potentially a fuel delivery issue (or lack of). I inspected the inside of the fuel tank (85gal aluminum) and the pickup tube for any debris, etc. It looked great.

The anti-siphon valve (a ball bearing in a sleeve) was all gunked up. I couldn't blow in it regardless of direction. I replaced that and also added a primer bulb inline to the fuel filter so I can see if there is suction in the fuel line (also helps prime the new fuel filter :) ).

After doing all that I started up the boat and it ran on the trailer and then stalled. I installed a new fuel pump. I restarted the engine and it stalled again. My fuel pump wasn't running. I disconnected the new pump and reconnected my old one. It didn't work either. I then traced the wires from the fuel pump up to the fuel relay. I disconnected it and tested with a multimeter. Everything checked out. I plugged the relay back together and wah-la the fuel pump primed and the engine started and ran fine.

I then replaced both relay's and set out for a nail biting sea trial. Everything worked!!! The WOT issue is gone as well.
 
You must log in or register to reply here.
Top