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DuaneS
08-30-2004, 05:55 PM
I have a 1998 200 Maristar with the 5.7 TBI. Lately the engine stalls when pulling a skier out of the water. I have found that when it happens and I stop and put the engine in neutral and rev to around 3000 rpm after 30 seconds or so the engine "clears its throat" and you can hear the rpm get smooth again. I've changed both filters several times this summer but it comes back after a couple hours operation. The nearest authorized shop is 4 hours away so I really need help from you pros. :confused:

MarkP
08-30-2004, 06:34 PM
Duane


You say changing “filters” helps out for a few hrs.. Did you look for water in the gas tank? Just a thought

MarkP
08-30-2004, 06:35 PM
Oh,

And welcome aboard....:toast:

JimN
08-30-2004, 08:59 PM
Any time you have a problem like this, look at the fuel system. Next, clean your flame arrestor. Carb cleaner works fine for this. I happen to like the NAPA cleaner that evaporates really fast.

Take a fuel sample and check the pressure. The easiest way I have found to take a sample is by using a fuel pressure gauge with a purge valve, pressing the button and letting some gas go into a clean, clear bottle. If you have a timing light, verify spark on all cylinders. If you have run out of gas more than once, your pump may have problems since the gas actually cools the impeller in the pump.

If you do a search for fuel related problems here or at the old site, you'll see a lot of people talking about the screen at the inlet of the pump. Remove the line from the tank after turning the anti-siphon valve closed(look at this first, just in case it turned a bit and is restricting the fuel flow from the tank). If you have a hose crimping tool, put that on the fuel line so the gas doesn't run into the bilge. There is a fitting on the pump where the screen is. You may find it easier to remove the pump to remove this. Most likely, there is some garbage in the screen. Get this out of the way and it should run great again.

Diesel
08-31-2004, 10:14 AM
Like Jim said check you fuel system first. If it continues to have issues I would look at the ignition system.

How many hours on your boat?
Has the SES light come on during one of these episodes?

The ignition system the TBI uses is notorious for having problems. The distributor shaft magnetic pickup loses its ability to send a signal to the module and it cuts out like you are describing. It is compounded when the engine is under load. Also a no load rev of the engine has been known to somehow "excite" or repolarize the pickup on the shaft to temporaraly fix the issue.

It is a headache to diagnose because in most cases it will not trip the SES or set a code until complete failure. Also the only way to fix it is rebuild the distributor shaft or replace the entire unit. If your boat has a lot of hours it is probably getting close anyway. Also I have seen many boats that have very few hours and are not run on a regular basis that need a distributor rebuild. I think the lack of use causes the shaft to loose its polarity faster than a boat that is used on a regular basis.

Hope it helps and good luck................ ;)

JimN
08-31-2004, 02:52 PM
Deisel- you mean notorious for problems in boats, or generally?

I wasn't aware of a code or indication for a distributor malfunction. On the other hand, the waveform from the pickup coil could be looked at on a 'scope to see if it's adequate. The pickup coil senses the gaps in the pole piece when they pass the coil and send a voltage spike to the IC module. The IC module then sends a square wave to the ECM to tell it the RPM. Also, the pickup coil isn't dealing with enough current to produce a high strength magnetic field in order to remagnetize the pole piece.

I still think it's fuel related, but not having seen the boat and not knowing the service history, it's hard to guess. How old are the cap and rotor, plugs and wires? Do the fuel pressure test and take a sample, then look at the other things.

Diesel
08-31-2004, 03:19 PM
Deisel- you mean notorious for problems in boats, or generally?

Generally, boat or truck.

I cannot tell you how many of these shafts I have replaced over the years. When I had my shop I kept a couple on the shelf ready to go. Some would last forever some would go at 40K :confused: .

I am sure you have seen this with your 90 model truck with 200K+.

I wasn't aware of a code or indication for a distributor malfunction.

This was my point. Without a code the problem is very hard to diagnose. IIRC once it would not run anymore it would usually trip a 42 or 43 DTC code identifying the ignition system as the source. It's been a while since I replaced one though (retired) :)

JimN
08-31-2004, 03:25 PM
What was the actual symptom on the trucks? Idle OK, then start getting lumpy, rev it up a bit and problem goes away? Mine does this occasionally, but there's never a problem with accceleration.

I would chalk it up to having a permanent magnet on a steel shaft, immersed in a magnetic field with a shield around it. Sounds like a recipe for eventual failure to me.

Diesel
08-31-2004, 03:40 PM
What was the actual symptom on the trucks? Idle OK, then start getting lumpy, rev it up a bit and problem goes away? Mine does this occasionally, but there's never a problem with accceleration.

I would chalk it up to having a permanent magnet on a steel shaft, immersed in a magnetic field with a shield around it. Sounds like a recipe for eventual failure to me.

Actually most people misdiagnosed as drivetrain. Going along the highway and it begins to mis or cut out like the trany was slipping. That was usually how the truck ended up in my shop; we specialized in drivetrain.

This usually occured in OD converter locked with a load (up hill usually). Most the time they idled fine and accelerated fairly well unless they were towing or in a low rpm load as described above.

Today most mechanics can't or won't do anything unless the scanner tells them the exact problem. :(

JimN
08-31-2004, 05:21 PM
Tell me if I'm wrong, it happens in OD, no load other than what's in the bed(not very much) at about 37 MPH? I thought it was bad to tow in OD.

Diesel
08-31-2004, 06:08 PM
Tell me if I'm wrong, it happens in OD, no load other than what's in the bed(not very much) at about 37 MPH? I thought it was bad to tow in OD.

What thread are your reading :confused: :D

Two Cases:

1. Highway speeds, OD converter locked, starting up hill creating a slight load, wham it starts cutting out. (not towing)

2. Towing, from a stop it begins bucking or cutting out. It will also do it when the engine has to work harder towing up hill on the hwy.

Sorry if I wasn't clear before but I don't know where you got the 37mph??

Yes, never tow in OD with a early generation 4L60; it generates too much heat if the converter slips and/or is busy between 3 and 4.

JimN
08-31-2004, 08:52 PM
I mentioned 37 MPH because mine occasionally bucks going uphill at 37. Not 35 or just under 40, 37 on the speedo. Haven't noticed any problem towing, just driving and it does it whether I'm in OD or not. Tranny was rebuilt last year and it happened before that.

DuaneS
08-31-2004, 10:12 PM
Some additional info: I have 369 hrs with about 50 so far this summer. I don't know if this helps but the last time it bogged down was when I was being pulled up. Being still in the water I had a different perspective on the sound. There was what looked like white smoke coming from the exhaust and it sounded very rough as my wife revved it. After about 20-30 seconds the RPM smoothed out and the smoke went away. I've not had the chance to check the tank/pickup/pump screen yet but it sure looks that if its not one of these items I've got to drag it to the shop. Thanks for the replies.

JimN
08-31-2004, 10:43 PM
Now it does sound like there is water in the tank. Take your fuel sample and lit it sit for awhile. You'll probably see water droplets settling to the bottom of the bottle or it may be cloudy. Hopefully, there isn't too much gas in the tank so it will be easier to drain it. If there is a lot of gas in it, you might want to call some auto shops to see what they do with water-contaminated gas.

jimmer2880
09-01-2004, 06:04 AM
Diesel - that's great info! Amazing the kind of people on this board. I'm looking at buying an older chevy (88-94ish) with 100k & basically drive it until the wheels fall off (40k a year). I'm sure I'll eventually end up with that problem. Nice to know.

THANKS!:dance:

Diesel
09-01-2004, 02:44 PM
I mentioned 37 MPH because mine occasionally bucks going uphill at 37. Not 35 or just under 40, 37 on the speedo. Haven't noticed any problem towing, just driving and it does it whether I'm in OD or not. Tranny was rebuilt last year and it happened before that.

Sounds like a distributor to me.

It is hard for me to say without driving but from experience I would look at the distributor shaft first. In my experience 9 times out of 10 on 87 to 95 model GM trucks bucking and cutting out was associated with the distributor shaft. Most trucks had issues in the scenerios described above but every now and then we had one that exhibited some off the wall symptoms. I always started with the distributor.

IIRC my cost on a new AC Delco unit was around $100 including module; add a cap and rotor and you are done. If yours has not been replaced it mgiht be time to look into it. It could save you from a side of the highway break down on your way to lake.

Hope it helps.

lakes Rick
09-01-2004, 05:52 PM
Now it does sound like there is water in the tank. Take your fuel sample and lit it sit for awhile. You'll probably see water droplets settling to the bottom of the bottle or it may be cloudy. Hopefully, there isn't too much gas in the tank so it will be easier to drain it. If there is a lot of gas in it, you might want to call some auto shops to see what they do with water-contaminated gas.

You might want to check your gas vent.. If the black guard on it breaks, you will get gas in your tank... Some threads on the old site about this....