Suzuki DF60 2004 Won't go above 3000 rpms No error codes

[go2ski]

I definitely think something with the electronics is wrong given the symptoms. I don’t hear anything wrong with the engine and it doesn’t die. Something is limiting its rpm’s

[go2ski]

redlowrey I just tested the neutral switch it works doesn’t go over 3000 rpms out of water and the electrodes were fine the engine doesn’t sound like it’s misfiring just won’t go over 3000 rpm.

[redlowrey]

It's on the bottom of the third page, neutral switch on. Run the engine on the muffs with the cowling off put it in to gear, be careful, and give it a squirt and see if it goes over three thousand rpm, that will test if it has a restriction in the cowl or exhaust gas is leaking out of the engine holder, also take the cover off the intake and make sure there is no restriction on the flame arrester at the throttle body, and pull the plugs to see whether the electrodes are black very important that you do that.

[go2ski]

redlowrey the engine was sitting in a yard for years and then we bought it with the boat for 1500. It was tooken to a mechanic and was completely re done and ran fine. The engine has only had problems the past year but we’ve had it for about 5 years. I’m gonna test the neutral switch tomorrow if I can’t see it on the SDS I’ll use a multimeter.

[redlowrey]

Mate the iac valve has got absolutely nothing to do with the engine not running over 3000 RPM, something else is wrong, on the first page of the sds manifold absolute pressure is very low 12in, hg with the engine running, does the engine idle smooth or rough, on a good running engine there would be around 16 to 18 in, hg, that would make the signal voltage on the map sensor high and I see that the injection pulse width is around 4 ms that is what a four litre engine would run at idle.
Need more history on the engine, did it used to run good or did you buy it like this. With the neutral switch your sds will tell you on or off depending on the shifter, you would know if the neutral switch off in neutral the engine would have a distinct hunt in the rpm ounce you were over 2.500 rpm. pull the plugs and have a look at the colour of the porcelin near the electrodes.

[go2ski]

Thanks for the advice I saw some other post say something about the neutral switch and was gonna try that next. I’m not sure if the sds shows it on and off I’ll look when I can and will post when I do.

[Murray]

To test Moonlighter’s theory you should be able, with the SDS hooked up, engine running in neutral change the gear to forward and the “Neutral Switch” should go from On to Off. Full disclosure: I’ve never used the SDS program so I could be wrong.

[Moonlighter]

May be the neutral throttle switch on the engine - on the starboard side gear linkages.

This switch tells the ecu if the engine is in gear or not. If the switch is broken or misaligned the ecu wont see the “in gear” signal and will electronically limit revs to about 3000rpm.

[go2ski]

The IAC valve recently broke and I replaced it. When it broke it only let me run the engine about 2000-3000 rpms at first and then finally stopped running (I had to get to the dock) and would die when switching into gears (it would run out of water above 3000rpms but in water, it would die when switching into gear in water). When I installed the new IAC valve I messed with the bypass air-screw too and the error for the IAC valve went away. It now will go into gear but will only run at 2000-3000 rpms with no errors showing in water. I have replaced the oil pressure switch thinking that could be a culprit but nothing changed. Any help? I have a service data attached with it running out of water. Service Data.pdf (The errors shown in the service data are there from before I haven't gotten any more errors since I installed the IAC valve