1989 Evinrude V4 90 HP. Ran like a top for the last 3 years until 3 weeks ago. I am stumped. I have ordered the factory manual, but it has not arrived yet. I need some troubleshooting things to check in the mean time. The kids are getting mad, no more tubing.
I bought this in 2009 from the original owner. I converted from VRO to the old style fuel pump and run 50:1 with Quicksilver oil mix all the time. The VRO pump had a crack in it. It has always had a slightly rough idle. I figured this was normal for a 90 HP. Above idle, goes very well (especially on a 700# 16? Starcraft).
It has run flawlessly until 3 weeks ago. We were tubing and it seemed like it was running out of gas after 30 minutes or so (it seemed early to switch tanks but I quickly switched them and pumped the bulb a few times and no change. The motor seemed to be starving. I moved the control to full throttle and the max it would go was 2300 RPM. That was it. I tried squeezing the bulb a few times again and no improvement. We slowly motored the 3 miles to the dock at 10 MPH. Normally 5300 RPM and 40 MPH. We trailered it home and it sat for a week.
The kids wanted to fish, after a look under the cover, for the obvious, I checked the fuel strainer on the pump and it looked clean. Reassembled, Idled in the driveway for a short time on the hose and it seemed back to normal and we took it to the lake. It screamed OK, for about 300 yards, 5300 RPM. Full speed perfectly then started to drop off again and back to 2300 RPM. It seemed to not be running on all 4. At an idle, it seemed to run real rough, stalling often. We shut it down, fished for 10-15 minutes, started again, it ran well again, perfect and full 5300 for 100? or so and then the same, 2300 RPM, seemed to skip and we motored it in again.
The next night after work I went ahead and cleaned the fuel pump strainer again (even though this does not seem like a fuel related issue) and took the pump apart, it all looked like new. I also checked fuel pump pressure (4-5 PSI). I checked compression Left Bank 110,110, Right Bank 125, 120. I checked each plug for spark with a timing light as well, all good. When I removed the upper left plug wire from the coil to see if it idled any worse, I noticed a spark from the plug coil connection to coil input wire. I had a spare coil and replaced it. Put it all back together, let it idle for a while in the yard and it seemed to run better.
We took it to the lake. It screamed great for about 15-20 minutes, 5300 RPM full speed perfectly, we were high-fiving but then it started to drop off again momentarily, back to 2300 RPM a few short times @ full throttle, then back to 5300 and ran well again. I squeezed the bulb when this happened, no change. We shut it down, I removed the engine cover, used the timing light on each wire, it seemed each was firing evenly. I left the cover off, it ran pretty well, but only reached 4400 RPM. Never 5300 again. 4400 was it and the idle seemed rough. The power pack seemed hot to the touch right after removing the cover. It seemed cooler with the cover removed. Anyway, 4400 back to the dock. I am not an outboard motor guy, but it seemed the timing is somewhat retarded.
After deciding it was not fuel, and having and Amazon gift card, I ordered a Power Pack. I replaced it and took it out again last night. Same thing, 4400 RPM is it. No 5300 at all. It seems to run OK at speed, but it could be running on 3 cylinders the best I can tell. I only removed the lower left wire from the plug after pulling the cover, and it seemed to make no difference at speed with the plug wire on or off. Lacking a plug wrench, I took it home.
I removed the bottom left plug, it was wet with gas/oil. The others were all dry. I replaced all the plugs with my last set that I cleaned and kept in the Glovebox. While in the driveway, on the hose, I pulled each wire and each made the idle real rough and each had a spark jumping over an inch. So I knew they are all firing (at idle at least). We took it to the lake again and no difference, 4400 RPM is it and a pretty rough idle.
Anyway, I need a checklist of things to check until my shop manual arrives. I am stumped! One final thing, my battery is not the best. I have 13.4V running at speed and 12.4-12.8 at idle. When off only 11.8 or so. Could it be a float in one of the carbs sticking? Rectifier? Stator? I just do not know.
Your help is very much appreciated.
I bought this in 2009 from the original owner. I converted from VRO to the old style fuel pump and run 50:1 with Quicksilver oil mix all the time. The VRO pump had a crack in it. It has always had a slightly rough idle. I figured this was normal for a 90 HP. Above idle, goes very well (especially on a 700# 16? Starcraft).
It has run flawlessly until 3 weeks ago. We were tubing and it seemed like it was running out of gas after 30 minutes or so (it seemed early to switch tanks but I quickly switched them and pumped the bulb a few times and no change. The motor seemed to be starving. I moved the control to full throttle and the max it would go was 2300 RPM. That was it. I tried squeezing the bulb a few times again and no improvement. We slowly motored the 3 miles to the dock at 10 MPH. Normally 5300 RPM and 40 MPH. We trailered it home and it sat for a week.
The kids wanted to fish, after a look under the cover, for the obvious, I checked the fuel strainer on the pump and it looked clean. Reassembled, Idled in the driveway for a short time on the hose and it seemed back to normal and we took it to the lake. It screamed OK, for about 300 yards, 5300 RPM. Full speed perfectly then started to drop off again and back to 2300 RPM. It seemed to not be running on all 4. At an idle, it seemed to run real rough, stalling often. We shut it down, fished for 10-15 minutes, started again, it ran well again, perfect and full 5300 for 100? or so and then the same, 2300 RPM, seemed to skip and we motored it in again.
The next night after work I went ahead and cleaned the fuel pump strainer again (even though this does not seem like a fuel related issue) and took the pump apart, it all looked like new. I also checked fuel pump pressure (4-5 PSI). I checked compression Left Bank 110,110, Right Bank 125, 120. I checked each plug for spark with a timing light as well, all good. When I removed the upper left plug wire from the coil to see if it idled any worse, I noticed a spark from the plug coil connection to coil input wire. I had a spare coil and replaced it. Put it all back together, let it idle for a while in the yard and it seemed to run better.
We took it to the lake. It screamed great for about 15-20 minutes, 5300 RPM full speed perfectly, we were high-fiving but then it started to drop off again momentarily, back to 2300 RPM a few short times @ full throttle, then back to 5300 and ran well again. I squeezed the bulb when this happened, no change. We shut it down, I removed the engine cover, used the timing light on each wire, it seemed each was firing evenly. I left the cover off, it ran pretty well, but only reached 4400 RPM. Never 5300 again. 4400 was it and the idle seemed rough. The power pack seemed hot to the touch right after removing the cover. It seemed cooler with the cover removed. Anyway, 4400 back to the dock. I am not an outboard motor guy, but it seemed the timing is somewhat retarded.
After deciding it was not fuel, and having and Amazon gift card, I ordered a Power Pack. I replaced it and took it out again last night. Same thing, 4400 RPM is it. No 5300 at all. It seems to run OK at speed, but it could be running on 3 cylinders the best I can tell. I only removed the lower left wire from the plug after pulling the cover, and it seemed to make no difference at speed with the plug wire on or off. Lacking a plug wrench, I took it home.
I removed the bottom left plug, it was wet with gas/oil. The others were all dry. I replaced all the plugs with my last set that I cleaned and kept in the Glovebox. While in the driveway, on the hose, I pulled each wire and each made the idle real rough and each had a spark jumping over an inch. So I knew they are all firing (at idle at least). We took it to the lake again and no difference, 4400 RPM is it and a pretty rough idle.
Anyway, I need a checklist of things to check until my shop manual arrives. I am stumped! One final thing, my battery is not the best. I have 13.4V running at speed and 12.4-12.8 at idle. When off only 11.8 or so. Could it be a float in one of the carbs sticking? Rectifier? Stator? I just do not know.
Your help is very much appreciated.
