'88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

[achilles555]

Hello all. For the past several months, I've been restoring a 1985 Charger Foxfire with a 1988 Mercury 150 XR4 on it. I finally had a chance to get it out on the water today (for the first time), and ran into some problems. I have done the following to this motor to date:

? Replaced water pump.
? Rebuilt fuel pump.
? Replaced the oil lines.
? Replaced 1 switch box.
? Drained and replaced lower unit oil.

When I got her out on the water, I ran into some trouble. The motor starts fine, and idles beautifully. The boat comes out of the hole quickly, and rides great. The problem begins when I get her going past about 1/4 throttle. Once on plane, and at about 1/4 throttle, it runs perfectly and purrs like a kitten.

Once I push it to about 1/2 throttle, the throttle control/housing starts intermittently beeping beep - beep - beeeeep - beep, and the motor begins to run rough. There is no pattern to the beeping, but it doesn't stop. The motor itself stops running smoothly at about 1/2 throttle, and the prop in the water starts to make a "garble" sound, like the prop is not running in clean water. The further I push the throttle, the higher the RPM's go, but the boat does not pick-up any speed. It just runs really rough, and won't go any faster.

I tried giving it gas around a corner to see if cavitation was the problem, but it didn't change anything. I'm really at a loss as to what the problem might be. Can anyone out there help me figure this out? Thanks so much ac.

 

[achilles555]

Update: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

Update: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

UPDATE: I have posted this question on a few different forums that I frequent, and I wanted to share a short list of some of the suggestions. Here goes:

1. The beeping is probably an indication that your oil pump is failing.

2. The running rough sounds like you've spun the hub on your prop.

3. Never replace only one switch box. If one was malfunctioning, it could have cross fired and perhaps damaged the other. Sometimes those switch boxes work perfect at the lower rpm ranges but then start doing really strange stuff at higher rpms.

4. If one of the switch boxes is still malfunctioning it could fire a cylinder out of order and detonate a piston.

5. The high speed side of your stator could be shot.

6. Sounds like a slipping prop-bush.

7. I'd check the ignition switch, oil level sender (blue wires) or overheat ClixOn switch (one tan wire, other side runs to ground). If you can, isolate (disconnect) the YEL/BLK wire under the hood from said unit. If problem persists, check control box and ignition switch for irregularities.

8. A sticky thermostat.

9. A bad oil injection sensor.

10. Check the Thermostat and Pittot Valves.

11.You have an overheating problem.

So this is the list that I have to work from so far this weekend. Is there anything here that I can knock-out quickly? Is there anything here that is obviosly incorrect? Let me know what you guys think about the solutions.

 

[hkeiner]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

You may have several independent problems going on at the same time. If I had your mix of possible problems, I would first confirm/elimate/fix the "spun prop" condition before tackling the other possible conditions. After that I would perform some basic troubleshooting tests to see if anything appears abnormal. If you simply "fix" all the possible causes in the list you have accumulated, you may spend a lot of time and money fixing the wrong things. Just my opinion...


In additon to a compression test, following are the two troubleshooting guides I use most often.

Ignition: http://dolphinmarineservice.homestead.com/ign5.html

Fuel: http://www.marinepartsman.com/Mercury-Marine-service-bulletins/Mercury-Mariner/2001/EN_17.PDF

 

[j_martin]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

There are only 2 alarms on that engine, oil injection failure, and overheat. Both are serious conditions.

Your description of pushing it hard while it's both failing and alarming make me think you've already done serious harm to your motor.

That engine's a screamer, but if you ignore alarms and faults, it will be a boat anchor quickly.

Get the manual, do some research, check it out and if you haven't wrecked it by now fix the problems before you run it.

I wish you well
John

 

[achilles555]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

j_martin, i'm glad to see you replied. i was hoping you would get a chance to read my post. I pre-mixed my fuel and oil 50:1 from the beginning. I figured this old motor could use the extra lubrication anyway. so, i don't think i've really messed anything up. like i said in my earlier posts, it sounds and runs GREAT in the lower rpm's. it's only when i get into the higher rpm's that the trouble starts.

what would you do in my situation? where would you start? also, could the problem be cavitation? could it be something as simple as that. does this motor have a "safe mode"? could an oil injection problem cause it to go into safe mode? thanks so much for your help.

one last thing. when i had this motor looked over by a mercury tech when i first got it, he said that the oil sending unit was bad (of the many other things that i have now fixed). i bought a new sending unit, but haven't installed it yet. could this be the sole source of these problems?

i've got the boat looking really nice...i'm just trying to get it to run right at this point. thanks again for all your help throughout this process. ac.

 

[achilles555]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

OK - I took the prop off, and it doesn't look like anything has been spun, unless I am missing something. I have posted some pics of the prop here:

http://www.flickr.com/photos/24479981@N03/

As for the beeping, I have a new oil sending unit. I am going to replace over the weekend, and see if that helps.

One other thing, when I left the cap off of the reserve tank on the front of the motor, I accidentally forgot to close it back before running it again. It lost some oil, but not much. I looked at that tank again tonight. It is full, but not to the brim. Maybe if I fill it all the way up, that will alleviate the alarm.

I am leaning toward the stator being bad as the cause of the poor performance past 1/4 throttle. I think that might be the problem. I would sure hate to drop $200 on a stator if it's not the real problem, though.

Any other advice out there would be greatly appreciated. AC

 

[j_martin]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

That motor ain't got no brains. It'll alarm, and you have to shut it down.

The oil pump has a sending unit on it. If it's bad, the alarm will sound.
The oil in the engine tank is supposed to be full to the top tight. If it isn't, the alarm will sound.

You fill it by loosening the cap while running and letting the oil system fill it from the boat tank till it leaks, then tighten the cap. don't overtighten it. They are cheep plastic like yer weed wacker and will split. only they are damned expensive.

The high speed miss could be either ignition or fuel. Both are common on this engine. First the ignition. Most common fault is either a defective switchbox, or a defective stator. (assuming multiple cylinder cutout at high speed.) The best thing is to do the dva (peak reading voltmeter) tests at the switchbox. That should isolate which one it is. If it proves to be switchboxes, it's better to replace with 2 used ones than one new one. They also are pretty pricey. Same thing with the stator. don't mix up 9 or 16 amp stators. They have similar part numbers, and don't put a 9 or 16 under a 40 amp flywheel. They'll toast in a heartbeat. (seen it) Stock on that engine is a 16, but it's possible to convert it to a 40. (I've done it.)

Usually if it's a fuel problem, pumping the bulb will make it run. Faults could be fuel pump, air leak anywhere in the suction side, from the pickup tube to the fuel pump. Aftermarket bayonet (plastic) fitting, aftermarket primer bulb and hose. (both inadequate for the needs of an XR4) There's a little finger sized fuel filter on that engine. If you have a bit of water in modern fuel, it'll form an almost invisible gel like chit that hangs in that filter. Symptoms will be it'll run like a raped ape for a minute or two after you change the filter, then revert to mis-behaving. You might have to rig a fuel pressure gauge to track it down.

Trying to run it if it's leaning out is a sure way to stick a piston, I don't care how much oil you're running.

BTW, I mix my tank fuel at 125:1 as insurance for VRO failure. I carry an extra quart of oil that'll go into the fuel I I alarm a ways from the dock. Both just common sense insurance, probably never be needed.

That 88 XR4 be one screamin' motor for a stocker. It's probably about 165 HP right out of the crate, and that little lower is slippery as an eel. I love mine. Take good care of it. Use Mercury High performance lube in it. If anything is out of adjustment or under lubed, it'll put the pinion out the side in short order. If it's well maintained, it'll run forever.

I'm fixin the transom so I don't twist that monster off. See it at the fiberglass forum of Screamandfly.com. Mine's mounted on a 88 Tracker 1800FS

hope it helps, good luck to ya
John

 

[j_martin]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

Just looked at your first post.

Do you have a water pressure gauge on that thing?. It sounds like your engine might be a little high. If it's high enough to pierce the surface with the prop, it's probably not getting enough cooling water. A gauge tells all.

BTW, that lower will run forever and throw a 100 foot rooster tail all day, but it don't like surface piercing. It just isn't heavy enough for the torsional vibration encountered in that application.

hope it helps
John

 

[achilles555]

Re: '88 Mercury 150 XR4 Beeping and Cutting Out - Need Help!

hi j_martin. Thanks for replying. I knew you would know better than anyone about my XR4. You've helped me a lot in the past. I do have a water pressure gauge, but it ain't working. I'm going to work on getting those gauges up and running this weekend.

I've replaced one of the switchboxes, and I just ordered another. The one that I already replaced is the outer switchbox. I hope the old one hasn't already fried the new one. I am also looking to buy a new stator, but this things are frickin' expensive. I might try to do some testing over the weekend before I sink $200 into a new stator without knowing it's the problem.

I'm going to print your response out and try a few things out this weekend. I'll report back monday or tuesday. Again, thanks for the help. AC.