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1998 Johnson 175 Ficht won't get out of the hole

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xyourobob12

Member
I put the boat in the water for the first time this season, she starts and idles just fine but when I put her under any load she starts bucking and when I open her up she makes lots of sputtering noises the prop is obviously turning but she won't get out of the hole.
When I winterized the motor it was running just fine, since then I have changed the plugs, filled her up with gas and topped off the oil. I wondering if what is happening is some sort of vapor lock in the fuel system? It's been years since I have had any problems with the engine so I am going to try and locate the diagnostics software, does anyone know if the tech software is available for download?
 
Check the shift interrupt switch.-----cuts spark to 3 cylinders when shifting.----Could be stuck.-----A no money spent inspection.
 
I checked the spark on each cylinder while she was in the driveway and I'm getting spark at idle, however when I took the plugs out to check compression two of the plugs had bent arms and clearly were not firing. Yes, these are the correct plugs for this engine! If I was a betting man the box of plugs got dropped somewhere between manufacturing and my purchase of them. I re-gapped these two plugs and before I put them back in. I ran the engine for 10 minutes and checked all of the plugs and nothing was bent. While I had the plugs out I checked compression and I am getting 85-90psi on all 6 cylinders. I put her back in the water and I still have the same problem.

A week later (boat is still in the water)
I could not figure out how to disconnect the ground on the shift interrupt switch to disable the switch. So with a cheapo spark tester I checked spark on each cylinder in neutral, when she is in drive and at full throttle - it appears I am getting spark at all times. Tomorrow I will swap out all of the plugs and see what I get.
 
I put another set of new plugs in and that didn't change a thing, I disconnected the shift interruption switch and still no change. When I swapped out the plugs it's evident that 3 of the pugs are blacker than the other three so I'm thinking something is throwing her into 'slow-mode"?
 
I have the software and the cable but for some reason its not seeing the engine. Either my cable has gone bad or a windows update has interfered with the drivers. The software used to work just fine, I'm willing to buy the software again but I can't find a source in North America.
 
Boobie said:
Check the throttle position sensor.
Click to expand...
This is a quick electrical check without needing the software. I can't remember if this is a 2-wire or 3-wire sensor. If it's 2-wire, simply unplug it from the harness, set your multimeter to ohms, place you probes on the connectors, then manually move the linkage and see if you get a smooth change of resistance through the entire range. If it's choppy or doesn't change then you likely have a bad TPS.

If it's 3-wire you'll need to back probe the ground and signal wires and with the key in the run position look for voltage when closed and watch for a change of voltage through the entire range. Again, if it's smooth then the TPS is good and if not it's time to replace.

KJ
 
A lot of software quit on the last Win10 update. My laptop with dongle to change water mixing valves quit and now have to up date driver boards in mixer to WiFi ($8K)
 
I was able to get my hands on the software and a cable, no faults thrown even when I ran the engine. The mechanic is 4-6 weeks out from looking at it and the season is slipping away. What to do next?
 
xyourobob12 said:
I was able to get my hands on the software and a cable, no faults thrown even when I ran the engine. The mechanic is 4-6 weeks out from looking at it and the season is slipping away. What to do next?
Click to expand...
As Boobie and I both said, Check the TPS. Often the TPS can be failed but not reporting errors to the EMM. If this sensor doesn't send proper signal to the EMM you won't get spark advance and fuel to match the increased air flow of the throttle body. The result is a bogging, bucking engine.

KJ
 
I was able to get over to the boat today again and continue the hunt. I put the engine in service mode by taking the TPS off the fly wheel but not disconnecting the harness, I secured the spring loaded arm to it's maximum position, turning the key to the on position and counting the lights. 1 code - TPS faulty (maybe this is normal because I have the TPS in full throttle mode?)
I put the ohm meter on the TPS and the numbers appear to move steadily upward until the arm is turned about 3/4 of the way and after that I lose all reading ( I think the highest number was about 3600 before it loses the reading.)
Based on this do you think I have a faulty TPS?
 
My new TPS arrived today, it behaves the same as the old one with the ohm meter test. I'll put it on the engine later this afternoon and post the results.
 
Unfortunately the new TPS did not correct the problem, I also put on a new Fuel/Water separator but I still have the same problem. I put the boat on a trailer in hopes that might trigger the mechanics to look at it sooner but I'm probably still 3 - 4 away from them looking at it. I'm ready to to move to the next stage of due diligence in identifying the problem.
 
I decided to check that I had put the spark plug wires on the correct spark plugs, I should have done that 3 weeks ago because I had #'s 3 & 5 swapped. It appears the problem is solved, thank you to every one contributed. My 1998 Johnson 175 Ficht with 1200 hours soldiers on.
 
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