All of a sudden can't take load

[TurboFan]

I did a search on this but didn't find a problem very similar to mine.

I had my 91XP out all weekend running great, then came back in for 5 mins and headed back out and would bog right out under load. Machine would start great consistently but can't go over 2000 RPM. Plugs look great, nice chocolate brown. Plugs and wires have ~4 hrs on them (BR7ES @ 0.020 and Taylor wires). I was quite low on fuel, but changed my valve to reserve and there was no change in performance. When I would slowly increase throttle it would gradually run up to 3000 RPM, and at one point it ran somewhat ok then after I shut it off for 3 mins it was back to not running under load. 3 hours later it was the same way, however gladly started right up and took me across the bay to get to the launch.

I wanted to get your thoughts on this before I go scratching my head with a wrench in my hand. I want to stress that the machine was running great all weekend, up to right before it was turned off.

Thanks guys.

[Y2GREY]

Your high speed coil on your stator may be showing it's age, I had several fail on the 91 2-pole ignitions, and just replaced one in my race boat. Engine suddenly acts very rich even though you never touched the carbs. You may try unloading the pump while riding the boat to see if she'll reach top end and then slow down as she loads up with fuel.

[Bill O'Neal]

My guess would be something has clogged up either the on-off-reserve switch or the carbs. Try cleaning everything, especially the carbs.
You may have some water in the bottom of your gas tank.

Make sure the little vent is not blocked where the hood covers it. If so, re-align the rubber pad and the vent hole.

[TurboFan]

Thanks guys, I will get on that tonight and report back.

[TurboFan]

Sorry for the book guys but this is what I did tonight:

I drained all the gas I could and found no signs of water.
Removed hose at inlet to fuel pump and was very easily able to suck gas through in Res and On positions.
Checked and cleaned the already clean filter in the fuel pump.
Filled up with fresh gas (I was about empty anyway)
Took it out on the lake with 2 set of plugs that didn't make a difference, both BR7ES @ 0.020

Starts up right away. With some throttle the RPM would bounce from 1500-2500, then ~20 seconds later from 2300-3500, then after another while once it could reach 4000 it would take off really well. As long as I didn't let it idle at all it would run like a champ. Once it was allowed to idle it would be another minute long process.

While on the water I turned both low speed jets +/- 3/8 turn from it's last known good setting and it seemed to make no difference. The change of plugs no difference either. If I pull the choke on the water it does go to die after a few seconds.

I started it up when I got home (started right away as always) and out of the water it revs real high no problem at all.

I appologize for the novel but I am sure it's better than not knowing what I have done. I have confidence that this is relatively common cause I remember even my old lawn trimmer was sort of like this. The part that boggles me is how it happened all of a sudden.

Thanks ever so much.

Wes

[Bill O'Neal]

If it feels like an electrical problem, known things that go wrong are the rectifier and the rev limiter in those old 580's.
Both cause erratic running above idle rpms.
Is the motor white or yellow?

[ July 08, 2003, 09:15 AM: Message edited by: Bill O'Neal ]

[TurboFan]

Bill, it's a yellow motor. I personally thought it felt like fuel stavation but it could be electical because I don't see both carbs messing up at once and there is great fuel flow right to the pump. It revs great out of the water.

[ July 08, 2003, 09:19 AM: Message edited by: TurboFan ]

[Bill O'Neal]

I had an 1988 Yellow motor SP too.
I'm not saying this is definately your problem, but I had one once that started fine everytime, even ran fine on the water for a few hundred yards at a time, then would lose power and bog badly, causing me to have to idle back to shore.
I changed eveything, cleaned everything and did all of the stuff that normally solves this type of problem.
I cleaned the fuel filter.
I changed the rectifier.
I changed the rev limiter.
I made sure the fuel tank vent hose outlet under the hood was not blocked.
I did a bunch of other things that didn't work.
After a couple of frustrating weeks, I removed the front cover and did not see anything wrong. But I removed the coil and CDI anyway. I found a broken wire in the wire loom between the CDI and the coil, right where the connector is at the coil. The connector was not broken. The wire inside of the plastic sheath was broken. I repaired it and it ran fine for the next couple of years until I sold it.

White motors have their electrical parts in the grey box where they do not viberate, so this only applies to yellow motors.

I would at least try to swap the rectifier and rev limiter before I pulled the front cover. That only takes a few minutes. They are located in the grey box. You can eliminate the rev limiter by disconnecting the brown wire. But, be advised, pulling the lanyard will not kill the motor if you disconnect it, so just do it for testing to see if it is your problem.

The symptoms of a bad rectifier is that the motor willl start fine, and may even run good (not always) on the trailer, but once in the water, it will not rev up and it will run very erratically, maybe even backfire. A non working rectifier causes dead batteries if bad long enough because it is what converts the ac power from the stator to dc power and charges your battery. The motor runs erratically with a bad rectifier because of the electrical noise it produces around the CDI. Very similiar to running non-restrictor sparkplugs, only worse.

[ July 08, 2003, 09:45 AM: Message edited by: Bill O'Neal ]

[TurboFan]

Thanks for the prompt replies, Bill. Come to think of it I did check the vent tube as you mentioned as well and it was fine.

Since I do not have spare parts for this machine I will try to bypass the revlimiter (disconnecting the brown wire as you mentioned) and check for broken wires where you mentioned. I have had the front cover off before when I made my new plug wires and I did have the coil loose although I wasn't too hard on the 3 wires going to the coil although they didn't look like they were in the best of shape. Therefore the only part I can't test real easy is the rectifier (unless it's generic??, a power diode even?)

It sounds like the CDI comes out easy anyway.

I'll be on this again this evening and report back. [img]smile.gif[/img]

[TurboFan]

Ok well typically I don't accept the immaculate conception when it comes to fixing things but I suppose this time I have to just believe it.

I found the rectifier and brown wire Bill was talking about. I took out the CDI and Coil and found no problems. I cleaned up a few contacts that weren't that bad then tossed it in the lake and all was well. I was sure it wasn't ignition but hey... Thanks for all the help. We'll see how long it goes good for.

Wes

[Stincee]

Bill,
this is the exact problem i'm having with the hx I bought from Roger. I've got the boat running great out of water, as soon as I put it in the water it falls on its face, never reaching rpm above 3200. When I got the hx, the idel screw was removed for some reason. I put a new one in and have it ideling around 3050 out of water. I have it running a little rich due to the new top end but nothing that should make that much of a difference in performance. Before I take it to the docks of puddingstone this week, is there anything in that grey electrical box that I should pay some attention too that may help out? Thanks

Would 87 octain have this kind of affect on a motor that has always used 107? Never really understood how it could. By the way compression is at 150 on both cylinders.

[ July 09, 2003, 12:09 AM: Message edited by: Stincee ]