engine dying

[kilgorekb]

Engine cuts out at around 7000. After it cuts out the first time, it will only run for about 2 minutes at any rpm over 3000. I installed the high flow fuel pumps. It did not cure the problem. Sounds like the engine is clicking also. Put on a tiny tach and both plug wires are alive. Any ideas?

 

[kilgorekb]

Scouring the forum, I've found these things to try:

Clean the RAVEs (did that last year).
Clicking is either normal pump rattle or a loose screw in the PTO flywheel.
Disconnect the red wire on rectifier (not sure what that does).
New plugs.

I'm leaning toward electrical since I rebuilt the carbs last season and just installed the new fuel pumps. Ignition coil?

My plugs are all the same color gray. Not light gray or dark gray.. just gray... that includes the ceramic. All the same color gray.

The symptoms seem to be that of an overheating cutoff. I run it at WOT, it cuts off.. then keeps cutting off while I limp to the dock. But there's no beeping or anything. Would the beep for overheating come from the same speaker as the other beeps (DESS key, low fuel)?

I think I looked at 40 threads on engine dying and not 1 of them were reported as solved. If they were solved, it was totally irrelevant to my issue.

 

[dbracela]

Does it sputter and die, or is it a sudden cut off? Both engines or just one? Have you checked the compression? How hot does it get (can you place your hand in the engine)? My overheat alarm runs off the same beeper as the DESS key, low fuel, etc.

 

[kilgorekb]

When at WOT, it's sudden. When at 5000 or 6000, it'll go down to about 4000 over a few seconds and then cut off.

Just the starboard engine.

I checked compression at the first of last season.. all were between 140 and 160.

Haven't tried putting my hand on it. Where should I touch it? Head cover, bottom end?

Well my beeper works.. and it doesn't beep, so does that rule out overheating?

 

[dbracela]

There's a way to test the overheat sensors, hopefully someone will chime in on that. I'd check the compression again. You said you rebuilt the carbs, did you check pop off and all that jazz? What happened when you unplugged the rectifier?

 

[dbracela]

Did you also change the fuel filters while you changed the pumps? Any chance of something simple like an air leak somewhere?

 

[kilgorekb]

Yes, I checked the popoff when I rebuilt the carbs.

I haven't unplugged the rectifier. I was just saying that I read that on another thread. What does that do and what will it prove?

Yes I changed the fuel filters. New ones are metal.

I had this problem before changing the fuel pumps. I was hoping new fuel pumps would fix it. It didn't. Along with the new fuel pumps, I installed new fuel line. I triple checked every connection in the fuel system at the time of installation (last week). All connections are tight.

 

[kilgorekb]

My plan for the next 2 days:

1. Check compression.
2. Install new plugs.
3. Lube cylinders (Manual doesn't specify how much XPS Lube to spray. Is it 1 second? 30 seconds?)
4. Grease PTO.
5. Check for loose screws in PTO.
6. Check RAVEs.
7. Check pump inlet.
8. Disconnect red rectifier wire (IF someone can tell me what that will prove.)
9. See how long it will run at 5000. If engine doesn't shut off, then go to WOT.
10. If it dies, place hand on engine to see how hot.

If someone feels like I should add to my list, please chime in. I won't hold you responsible for follow-up advising.

 

[kicker]

If the rectifier is starting malfunction it will send mixed signals to your MPEM, causing random intermittent things to happen. The fail safes within the MPEM get triggered cutting rpms down, limiting power etc. Your battery will not charge when it is unplugged, but you can run it a while without it.

 

[kilgorekb]

Thanks kicker.

 

[kilgorekb]

Why disconnect just the red wire? Can I just unplug the whole connector? Or instead of digging out the red female terminal, can I just take out the 15A fuse from the ebox?

 

[kilgorekb]

Why disconnect just the red wire? Can I just unplug the whole connector? Or instead of digging out the red female terminal, can I just take out the 15A fuse from the ebox?

And wouldn't I have to pull both rectifiers since they're on the same circuit? In theory, it appears that a bad port-side rectifier could cause starboard-side engine problems... or vice-versa.

Assuming that a bad rectifier is the cause of my starboard engine problems:
1. It could be either rectifier that is bad.
2. The mixed signal that bad rectifier sends to the MPEM always results in the MPEM shutting off my starboard engine.... as opposed to the shutting off the port engine.
3. The mixed signal is actually either AC (assuming a bad rectifier will allow AC to "leak" into the circuit,) or DC that is not constant within tolerance.

That's what I get from the shop manual. But I'm not a scientist.

 

[Sportster-2001-951C-Stock]

If you want to eliminate one or both RR's you can disconnect them separately or both, to isolate the problem. And yes, I'd look for the RR fuse(s) first as it's possibly easiest to remove than disconnecting something else like the red or yellow wires. Pulling the entire connector going to the RR is fair game as well. I suppose you have only one cranking battery, so really the boat doesn't need two charging systems while both motors are underway, one operational RR/stator set is enough to keep the voltage up as long as it's not fuel injected or you have an thirsty electrical load such as a big honkin' stereo.

Measure the voltage, mine runs around 13.8v while running in water, last I measured. anything less than 12.8v isn't enough to charge(not charging) the battery and anything much more than ~14.2v is probably more than it should be(not regulating) and suspect.

The clicking sound in water underway description is disturbing, is this only under heavy load (like WOT), if so then could be detonation. Or maybe something's just vibrating (such as a metallic bracket?).

 

[Sportster-2001-951C-Stock]

If this is a 2-stroke, your plugs should level off to a cardboard brown color, gray is too lean or maybe not enough oil. Hopefully you confirmed your oil pump lever adjustment after installing and adjusting the carbs.

A fresh set of plugs in mine will be yellowish after the first 20 minutes or so, they eventually become brown after a few hours.

 

[Sportster-2001-951C-Stock]

My plan for the next 2 days:

1. Check compression.
*Early and often!
2. Install new plugs.
*Good to see fresh color of fuel film growth, not necessary if motor isn't missing or rough. Should start off yellow and eventually turn cardboard brown as the fuel film grows on the insulator.
3. Lube cylinders (Manual doesn't specify how much XPS Lube to spray. Is it 1 second? 30 seconds?)
*A couple of teaspoons, enough to coat the cylinders but not make puddles, crank electric starter before installing spark plugs to expel excess oil. This oil will only remain there for a short period of time, maybe up to a couple of minutes before it is diluted and expelled out the exhaust.
4. Grease PTO.
*Early and often, to feed hungry grease worms living in the splines. Just enough to see shaft move.
5. Check for loose screws in PTO.
*Also the torqued-off nut behind the wheel!
6. Check RAVEs.
Probably need this twice/season or when RPM's drop off.
7. Check pump inlet.
*No mangled soda bottles, river rock, truck tires or plastic shopping bags inside pump please!
8. Disconnect red rectifier wire (IF someone can tell me what that will prove.)
*If the rectifier isn't regulating voltage or if one of the internal diodes is shorted/leaky then AC passing through RR and floating in DC circuit will interfere with spark ignition much as the symptom you describe. Might not effect both engines, one will be more sensitive then the other. If one of the diodes is completely shorted, most likely the RR fuse will blow.
9. See how long it will run at 5000. If engine doesn't shut off, then go to WOT.
*Okay, if engines accelerate normally as they should, no symptoms of flat lean hesitation throttle response. The reason is, a lean air/fuel mixture will cause detonation and overheat your pistons. Detonation is defined as the fuel inside the cylinder during the compression stroke stops burning prematurely (as in not enough fuel). This is usually detected by flat throttle response, ie: you have to nurse the throttles to get engines up out of the hole, they lean die easily at no wake speeds. Could be lean condition is caused by an air leak down stream of carb in the intake tract (such as missing or torn carb base gasket, damaged crankshaft oil seal).
10. If it dies, place hand on engine to see how hot.
*Should be able to keep hand on engine without being burned, could be uncomfortably hot.

If someone feels like I should add to my list, please chime in. I won't hold you responsible for follow-up advising.

 

[jhjesse]

OK when did the problem start, before or after the fuel pump exchange?
If it was before then I would rule out the rectifiers. The rectifiers are probably 15 years old and probably should just replace them. Your boat is exactly like mine...so I am assuming your rectifiers are mounted on the front of the engine with easy access?

If the problem started when you changed the fuel pumps I would take a hard look at the filters if they are the cheap plastic kind. Are they 5/16 ports or 1/4."
With those plugs being gray there is a better that good chance your engine is starving for fuel. Good luck !

 

[kilgorekb]

The problem started b4 the new fuel pumps.

The oil pump was not aligned. It was about 10 degrees retarded. It is now dead on.

RAVEs slide easy.

The carb low speed mix screws were off about 1/4 turn. It is now dead on.

Idle was off. Its now dead on.

Compression is 160 and 165.

Lubed cylinders.

Installed new plugs.

Checked MPEM fuses.

Checked resistance at primary on ignition coils. Spec is 0.6. Starboard (problem side) tested at 0.8. Port tested at 2.0. Go figure.

Tried to check voltage at primary on ignition coil but got a really low reading. 0.7V. Spec is 20V. Does the engine need to be cranked for that test. Battery was on and key was in DESS.

Didnt see any screws on PTO. I guess theyre behind the flywheel.

Greased PTO.

Cranked on trailer. No clicking.

Will take to water tomorrow.

 

[jhjesse]

Sounds good. Hope everything goes well.

 

[kilgorekb]

Engine is running like a champ.

Disconnected starboard rectifier. Ran at 5000 for 15 minutes. Ran at 6000 for 5 minutes. Ran at WOT for 5 minutes. Connected starboard rectifier. Ran at WOT for 5 minutes. No problems.

So.... possible causes of previous problem:

1. Bad gas in bottom of tank.
2. Plugs were fouled bc of incorrect low speed screw setting.
3. Engine will cut off at WOT if engine is not warmed up.

Could not have been oil pump. Problem started before oil pump got misaligned.

Ill test possible cause #3 next time im out.

New problem: speedometer was bouncing all over the place. Stuck at 0 several times. When i blew the horn it came back to life everytime. Will browse threads b4 starting a new one.

 

[Sportster-2001-951C-Stock]

I don't think it's reasonable to WOT a cold motor unless you want it to partial seize, they need at least 3 minutes of warm up IMO.

I think your boat has both port and starboard RR but can't troubleshoot a problem there until after it begins to occur.

A too rich mixture will show up as fouling black soot or very dark brown fouling (ie: plug electrodes not getting hot enough to burn off fuel film.). Too rich will also drop your WOT RPM's. 7000 RPM is approaching your limiter cutout, I think.

 

[jhjesse]

Good to hear. Glad your boat is running better.

Have fun.

 

[kilgorekb]

I don't think it's reasonable to WOT a cold motor unless you want it to partial seize, they need at least 3 minutes of warm up IMO.

I think your boat has both port and starboard RR but can't troubleshoot a problem there until after it begins to occur.

A too rich mixture will show up as fouling black soot or very dark brown fouling (ie: plug electrodes not getting hot enough to burn off fuel film.). Too rich will also drop your WOT RPM's. 7000 RPM is approaching your limiter cutout, I think.

Correction: Old plugs were black and sooty. When i reported gray, that was incorrect. They looked gray at night. In daylight, they were black. Sorry for the bad info.

And it alaways idles for 10 minutes at the dock while we park the trailer. I was assuming that was enough to warm up the engine, but maybe not.