JustSomeGuy
New member
Motor is a 1992 40hp, J40TLENM. Man, where to start. The last time I had it running on the water was in 2023. It had the idle issue then but I "lived with it." This year I decided to try and get past it so I just put in Sierra carb kits, and did everything down to pulling and replacing the lead shots. I adjusted all of the linkage to spec from the shop manual. I disconnected the fuel hose from the motor, and used the primer bulb to manually pump all of the old gas out of the tank. I then added about a quart of fresh gas, and pumped some more to get the old gas out of the line. Then added 2 more fresh gallons to the tank.
I pulled it out of the shop and, after awhile, did manage to get it running - barely. Max 10-20 seconds at a time. I had to hold in on the primer or it would die out. It was smoking like a chimney. I pulled the plugs and verified I have spark. I've got 122psi/128psi compression. The plugs were actually super oily so I was thinking I was just running rich. Next day I went to pull it out of the shop and there was a huge puddle of watery oil under the motor, way more oil than I've seen even after a day at the lake. Easily a few ounces of oil, with water mixed in. I pulled it out of the shop to give it another go, but this time the horn stayed steady before I cranked it. I thought steady was the overheat alarm, so I ignored it. After cranking for 5-10 seconds, the alarm did stop. I managed to get it running long enough to get it up to operating temp. Once it was up to temp, it did run a little better, and would stay running with the fast idle lever about 15% of the way up. I ran it as slow as I could keep it going and adjusted the low speed needles. Never could get it running anywhere close to what I'd call "lean" like the shop manual says - it was always blowing quite a lot of blue smoke. The horn never sounded while it was running. Water coming out of the telltale was warmer than tap so the thermostat was almost certainly fine.
When looking in the carb throats there was a small puddle of really thick fuel in front of the butterflies at idle. Way thicker than what I'd call a "normal" fuel to oil ratio.
Next thing I wanted to figure out was the pesky alarm. I thought the oil alarm was pulses, not steady, but the only thing that made sense was the oil alarm, as in oil maybe leaking from VRO pump and triggering the alarm, until it gets pumped back up. So I traced the wires from the tank sensor into the motor housing and disconnected the black one. No more alarm. So it seems to be oil related. The tank is about 1/3 full of oil by the way. And the alarm STOPS after a few seconds of cranking.
Next thing I noticed: I had air in my fuel filter. I know for a fact it was full when I last tested because I watched it fill as I pumped the primer bulb.
NEXT next thing I noticed: A drip of oil coming out of the seam on the side of the VRO pump.
My theory is it won't idle well since it's trying to run way too oil-rich. This could either be due to air in the fuel line causing a bad ratio, or seals in the VRO going bad and it's dumping too much oil in the mix. Considering the external leak, I think the safe bet is the VRO pump has bad seals. Maybe the bad seals could let air back into the fuel line too?
I'm just looking for voices of experience and others' input on this. If it is likely the VRO, I'm going to delete it and do a standard pump and pre-mix. But I don't want to do it just because "VRO bad."
I pulled it out of the shop and, after awhile, did manage to get it running - barely. Max 10-20 seconds at a time. I had to hold in on the primer or it would die out. It was smoking like a chimney. I pulled the plugs and verified I have spark. I've got 122psi/128psi compression. The plugs were actually super oily so I was thinking I was just running rich. Next day I went to pull it out of the shop and there was a huge puddle of watery oil under the motor, way more oil than I've seen even after a day at the lake. Easily a few ounces of oil, with water mixed in. I pulled it out of the shop to give it another go, but this time the horn stayed steady before I cranked it. I thought steady was the overheat alarm, so I ignored it. After cranking for 5-10 seconds, the alarm did stop. I managed to get it running long enough to get it up to operating temp. Once it was up to temp, it did run a little better, and would stay running with the fast idle lever about 15% of the way up. I ran it as slow as I could keep it going and adjusted the low speed needles. Never could get it running anywhere close to what I'd call "lean" like the shop manual says - it was always blowing quite a lot of blue smoke. The horn never sounded while it was running. Water coming out of the telltale was warmer than tap so the thermostat was almost certainly fine.
When looking in the carb throats there was a small puddle of really thick fuel in front of the butterflies at idle. Way thicker than what I'd call a "normal" fuel to oil ratio.
Next thing I wanted to figure out was the pesky alarm. I thought the oil alarm was pulses, not steady, but the only thing that made sense was the oil alarm, as in oil maybe leaking from VRO pump and triggering the alarm, until it gets pumped back up. So I traced the wires from the tank sensor into the motor housing and disconnected the black one. No more alarm. So it seems to be oil related. The tank is about 1/3 full of oil by the way. And the alarm STOPS after a few seconds of cranking.
Next thing I noticed: I had air in my fuel filter. I know for a fact it was full when I last tested because I watched it fill as I pumped the primer bulb.
NEXT next thing I noticed: A drip of oil coming out of the seam on the side of the VRO pump.
My theory is it won't idle well since it's trying to run way too oil-rich. This could either be due to air in the fuel line causing a bad ratio, or seals in the VRO going bad and it's dumping too much oil in the mix. Considering the external leak, I think the safe bet is the VRO pump has bad seals. Maybe the bad seals could let air back into the fuel line too?
I'm just looking for voices of experience and others' input on this. If it is likely the VRO, I'm going to delete it and do a standard pump and pre-mix. But I don't want to do it just because "VRO bad."