1983 Evinrude 140 HP won't go over 3000 rpm

[MakoScott]

Hello everyone,

I was out driving my boat at 25 MPH (5000 RPM) when it suddenly dropped to 10 MPH (3000 RPM) The only thing I did different was to adjust the timing at the dock to get it to 24 degrees without the plugs in it, cranking it WOT with a spark gap tester connected and timing light. Ran great for the first 30 minutes and then had the trouble. I limped back tot the dock checked all the connectors, throttle cable, popped the plugs 2 looked a drier than the others but all looked like they were firing. I did a spark gap test and all 4 are bright blue spark. I changed out the external quicksilver filter /water separator, started the motor Idled fine (maybe a little more smoke than normal). seemed OK until I opened it up a bit and still can't get over 3000 RPM. I read about the temperature sensors causing a SLOW system to kick in but my sensors go to an alarm not to the power packs so I don't think there is a cutout system in place. Motor seems to be warm not hot to the touch and the water pump is putting out a solid stream of water (thermostats were changed last year). There is no oilier system in place I mix 50 to 1 ratio with high test unleaded. The rebuilt power head is 1 year old, the fuel pumps, stator, coils, wires, all hoses, power packs are also a year old. I rebuilt a set of carbs correct for the motor this year and they seemed fine and made the motor idle much better. I'm doing a compression test tonight and will report the numbers. I'm guessing it could be one of the fuel pumps went bad so I ordered a spare just in case. Any thing else I can check while I'm at the dock tonight? I also put the motor in neutral and the prop spins freely in both directions so I don't think there is any fishing line wrapped in the prop.

Thank you
Scott

 

[racerone]

No S.L.O.W on that motor.------A compression test must be done first.-----??---Two fuel pumps on it , why ?-----Any pictures of the 2 pumps ?-----Timing on these motors normally requires no adjustment.

 

[MakoScott]

Two fuel pumps are standard on the motor 1 for each carb. I can take a photo but they are Sierra 18-7352 pumps. Needed to set the timing because I swapped out replacement throttle linkage early in the summer and was just getting to setting the timing right I'll let you know the compression test results tonight
Thanks,

 

[racerone]

I do not believe it left the factory with 2 fuel pumps.----Parts book shows pump and states 1 required.-----I have many of these V-4 crossflows and not one of them has 2 pumps.----What size boat is the motor on ?

 

[interalian]

Hang a timing light on each cylinder in turn when trying WOT runs. Sounds like you've lost ignition on one hole. Surprising how much that sapps power.

 

[MakoScott]

Thanks for the responce.
Model E140TRLCTE 140 HP Evinrude It is a 1983 motor​

 

[tblshur]

MacoScott i have same motor had same problem it was power pack hope this helps:joyous:

 

[MakoScott]

Thank you for the response. Would a bad power pack still give me bright blue spark on a gap jump test? I do have a spare from the rebuild I can try that after taking a look with a timing light tonight. Is there any harm to the ignition if I pull the spark plug boot off one at a time to see which if any cylinders might not be fouling (with insulated pliers)?

 

[MakoScott]

I do not believe it left the factory with 2 fuel pumps.----Parts book shows pump and states 1 required.-----I have many of these V-4 crossflows and not one of them has 2 pumps.----What size boat is the motor on ?

Hi Racerone, It is on a 19 foot Mako center console vintage 1970"s. What type of splitter does your parts books show when using a single fuel pump. I thought it came with 2 fuel pumps since I got it that way used. The OMC manual doesn't show any carburetor line routing just some basic pictures

Thanks

 

[racerone]

All the parts books show that motor with one pump !----Why try and argue ??

 

[interalian]

Maybe send us some pictures of your fuel system. We like pictures. The factory used a plastic fitting to take fuel to each carb. It's fed from below with one line from the pump (item 11).

As for chasing an ignition problem, before condemning the power pack, try switching the coils. You'll need to poke the orange wires out of the rubber plugs. I had a coil fail.

 

[MakoScott]

Thanks for the reply interalian I'll take photos tonight.

Racerone, I'm not trying to argue just trying to understand.

 

[racerone]

Someone altered your fuel system.----Perhaps hoping for more speed.-----Post compression numbers first.

 

[MakoScott]

First things first, Racerone you were completely right about the single fuel pump. Not sure why I was convinced I replaced 2 of them when I put the motor back together, sorry for the confusion.

OK here is what I have for compression all cylinders are between 125 and 130 with WOT
removing each of the top 2 plugs made the motor run very rough.
removing each of the bottom 2 plugs made very little difference, it did surge a bit when the wires were put back on.

Since the power pack and coils are separate systems for each side and the spark gap test was so good I don't think there is an ignition issue.

I checked all the lines for leaks, wires for corrosion, all looks good

Does it make sense that it might be the lower carb has an issue like the float is sticking? I replaced all the jets when I rebuilt them I checked the carb linkage and it is connected and they seem to move in sync. I will remove the Air silencer tomorrow and make sure the butterflies and fully opening. Anything else I could check before removing the lower carb?

Thanks again for your help

 

[MakoScott]

Pulling it out of the water today. I'll let you know what I find.

 

[MakoScott]

The bottom linkage was not connected so only the top carb was working with the throttle. I drilled a small hole in the end of the linkage rod and put a thin washer and cotterpin through it to prevent the issue in the future. The rod does snap in tightly into the nylon connector but maybe its getting old.

Hope this post helps someone else..

MakoScott