I am having a couple of issues with my 1992 s83p. Only had it a few weeks but have been going through this forum and threads to solve issues, but so far haven't had much luck on this issue (lots others have been fixed). Figured since I have hit about 50 hours and a couple cases of beer worth of maintenance and trouble shooting that I can now post an original thread... The truck currently starts with just a single hit of the starter either hot or cold, idles smooth and low (I can get it to idle under 500 rpm smooth). Runs well, lacking power currently but gets up to 55 kph with some patience. My Problem(s) and Symptom(s): When I so much as touch the accelerator, the rpms spike and slowly drop down to idle. If idling at 1000, it will jump to ~3500 or better then hold for ~1-2 seconds then slow drop over ~2 seconds. Sometimes it will jump to a point it seems that it may harm the motor. The throttle springs back quickly, easily, and smoothly while engine is off, so I suspect it is a vacuum return or other vac system holding it open. Exhaust smells fuely/rich, particularly while rpms spike While running it around, the exhaust pipes get very hot - smoked a 400 F rated wrap I used to cover some small holes in the tailpipe behind the muffler (should have bought a higher temp rated one but i'm being cheap) Side note - the coolant was replaced improperly, will need to use the water can trick when I change it - heater core is currently dry but we are not overheating What I have completed: Replaced all vac lines (one at a time to maintain routing) Replaced all fuel lines Installed a fuel regulator after fuel pump before carb Fuel pump works, return line works Drained fuel, rinsed tank, non-ethanol fuel with Seafoam (2oz per gal) New fuel filter Oil change with filter Bypass charcoal canisters and installed one way valve to relieve tank pressure Seafoam and soak carb 12hrs (while mounted, did not remove) Checked idle stop solenoid, functions correctly Replaced a broken TVSV (suspicious this is incorrectly routed Likely some things I have missed My thoughts: Vacuum throttle return not working - not sure where or how to test this Choke sticking while throttle is actuated Accelerator pump sticking while throttle actuated - or is over zealous Some load - detecting system that applies throttle under load (such as dump pto activation) is getting triggered by throttle actuation (is this a thing on these?) Other carb issues from likely being set around with ethanol fuel for unknown time At this point I am at a loss for why the throttle spikes and stays high - hopeful for any hints or leads (or one of those magic wands that I have heard of). Currently using a spare carb spring to pull the throttle back so it doesn't hurt itself - makes the pedal stiff though. This will always be an off-road rig, so emissions are not a concern if it matters for a fix.
I had the same issue with my S110P, after rebuilding carb, new carb. As the hijet will be used by both my wife and I (ranch hay truck), a little more reliability was needed. I purchased a motorcycle carb kit online (no electrical, no vacuum lines) and after 2 hrs installing, it fired right up and runs like a dream. Here is the kit if you are interested: https://www.ebay.com/itm/305198321123
What did you end up doing with all the vacuum lines? Just plug them all off or is there a better route to take? Sounds like an easy fix if it is just plugging lines. Do you experience any issues with performance/latency? Also was there any need to adjust the timing? I am hesitant to replace the carb without vac lines as it seems like there would be some adverse performance... But I am pretty new to this game.
I left the vacuum lines to "necessary" sensors, but yanked just about everything else. The only downside that I potentially see is cold starting during winter. Timing has not been adjusted, or found a need to rejet the carb. I have adjust idle and that is about it. Response is snappy and it does much better with the hills than the old carb did
