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View Full Version : 95 Maristar 200 starting problem


ahhudgins
07-02-2009, 10:30 PM
Thought I would throw this out to everyone before taking it to the dealership. It's a 350 with fuel injection (looks like a carb with 2 injectors). Since I bought it 4 years ago, it has always cranked for about 4 or 5 seconds on the ramp before firing up, and I just assumed this was normal. The last two weekends it has been cranking and not starting at different times during the day. The motor could be hot, warm, or cold and it would do it at different times. My electric fuel pump runs at the first key click and I replaced the fuel filter today. I'm an electronics technician so I hooked a scope to the injector wires. When the motor doesn't start there are no firing pulses to the injectors. If the motor hesitates or shudders when it starts up, the pulse width on the injectors will vary so it appears to be an electronic problem. Anyone ever have this problem before? I'm going to try and get a service manual from my dealer with schematics to see what sensors are involved, I just don't want a mechanic to start swapping things out at random and costing me a fortune. When I called the dealer he said "sounds like the fuel pump, I'd replace it..." I'd rather check things before replacing them, and I also don't want to get towed by an Ski Nautique.

JimN
07-02-2009, 11:49 PM
The distributor sends tach info to the ECM and without this, it won't latch the fuel pump relay, won't trigger the injectors, won't tell the IC module to cause spark, etc. Look for the purple/white wire in the four wire plug to the distributor and, using a stick pin slid past the green silicone rubber seal, make contact with the terminal on that wire. Use a digital multi-meter set to DC volts and crank it- you should see 1-2VDC on this wire. If you need another person to crank it while you make sure the pin is in contact, do that.

If you want to check for codes, you can do it easily enough but there aren't many sensor issues that will cause a crank/no fire situation.

Remove the flame arrestor and watch for the fuel spray cone from the injectors- it should be a complete cone with no voids. While you're at it- when did you clean the arrestor last? How old is your impeller?

BTW- any GM mechanic should know how to troubleshoot this.

dummy
07-02-2009, 11:49 PM
Nautiques are fine. It's the Chaparral you won't live down.

JimN or somebody else should chime in with some good tech advise. He's all about checking for the problem before throwing replacement parts at something, so you're on the right track.

FYI - It's Throttle Body Injection (TBI) you're dealing with. Probably the Crank Position Sensor(s) but I wouldn't know for sure. Good luck.

JimN
07-03-2009, 12:35 AM
TBI of that vintage didn't have crank position sensors- it used the distributor to tell the ECM where the motor was, based on the assumption that the motor was assembled correctly.

ahhudgins
07-03-2009, 11:23 AM
The impeller is new, put a new one in every spring whether it needs it or not. The boat started almost perfectly every day this week on the trailer. Went out this morning before taking it back to the lake and had to crank it for about 30 seconds before it would fire up. When this problem occurs, I might get one or two spits from the injectors but usually nothing at all (No firing pulses to the injectors). When the motor does start, I’ve always thought it would idle a little ruff, and it’s that way all day long. Mastercraft told me that it’s just the nature of that system. The spray from the injectors is cone shaped but it’s pulsing on and off several times a second. I am going to check and make sure the fuel pump has voltage all the time (should have done that first), spark at the plugs, and check the signal from the distributor.

Is it normal for this system to crank for a few seconds when it’s cold, or should it just fire right up when the key is turned? Taking it back to the lake for the weekend and keeping my fingers crossed. Out numbered by Nautiques 2/1 so I will get a hard time if I get towed.
Thanks for everyone’s help.

JimN
07-03-2009, 12:29 PM
The impeller is new, put a new one in every spring whether it needs it or not. The boat started almost perfectly every day this week on the trailer. Went out this morning before taking it back to the lake and had to crank it for about 30 seconds before it would fire up. When this problem occurs, I might get one or two spits from the injectors but usually nothing at all (No firing pulses to the injectors). When the motor does start, Iíve always thought it would idle a little ruff, and itís that way all day long. Mastercraft told me that itís just the nature of that system. The spray from the injectors is cone shaped but itís pulsing on and off several times a second. I am going to check and make sure the fuel pump has voltage all the time (should have done that first), spark at the plugs, and check the signal from the distributor.

Is it normal for this system to crank for a few seconds when itís cold, or should it just fire right up when the key is turned? Taking it back to the lake for the weekend and keeping my fingers crossed. Out numbered by Nautiques 2/1 so I will get a hard time if I get towed.
Thanks for everyoneís help.

Rough? My truck is velvet smooth and that goes for the vast majority of the TBI motors I worked on, Usually, the cap/plugs/rotor/wires are to blame when it's rough. If it runs smooth on the trailer and not after it goes for a ride on the trailer, it would seem like something is loose and isn't making good contact, which brings us back to my recommendation to look at the grounds, do a wiggle test (something I often mention in other threads dealing with the same issues) and the easiest thing to do- look at the wires and connections. A lot of problems are solved by just looking for loose or corroded terminals and wires. Plugs wiggle loose, even when they have a retainer clip.

chico
07-05-2009, 09:11 PM
Pull the distributor cap off and put a flashlight on the reluctor wheel on top of the distributor shaft and look for small cracks in the magnet.

ahhudgins
07-06-2009, 09:00 PM
The boat started fine most of the weekend except for 2 times it cranked a little longer than normal or shuddered a little bit before smoothing out. When the engine DIDN'T fire up, there was no voltage to the fuel pump, no voltage to the injectors, but I DID have the tach signal out on the purple/white wire on the distributor (0 to 6V square wave). The problem is very intermittent so I know it's going to be hard to find. I already did the "wiggle test" on my wire harnesses when it was running and it made no difference. Once it starts, it's good to go. I'm calling MC tomorrow to see if I can get a service manual for that ECM system. If I can get a wiring diagram I think I can figure it out on my own. For example, I had no idea that I needed the tach signal in order for the fuel pump to come on, and I don't know if 6V signal is OK, or shoud it be 12V? I will keep trying everyone's suggestions, they have already saved me from buying fuel pump as MC suggested. Thanks again.

JimN
07-06-2009, 09:18 PM
The boat started fine most of the weekend except for 2 times it cranked a little longer than normal or shuddered a little bit before smoothing out. When the engine DIDN'T fire up, there was no voltage to the fuel pump, no voltage to the injectors, but I DID have the tach signal out on the purple/white wire on the distributor (0 to 6V square wave). The problem is very intermittent so I know it's going to be hard to find. I already did the "wiggle test" on my wire harnesses when it was running and it made no difference. Once it starts, it's good to go. I'm calling MC tomorrow to see if I can get a service manual for that ECM system. If I can get a wiring diagram I think I can figure it out on my own. For example, I had no idea that I needed the tach signal in order for the fuel pump to come on, and I don't know if 6V signal is OK, or should it be 12V? I will keep trying everyone's suggestions, they have already saved me from buying fuel pump as MC suggested. Thanks again.

The tach voltage should be 1V-2V, using the DC scale. That's close enough for checking the tach signal in a crank/no fire situation. 6V is high but if you were using a scope, it will read higher, anyway. Next time it fails to fire, check the green wire at the fuel pump relay for signal. This will be grounding if the relay's pin 85 is red and positive if there's no red wire at either pin 85 or 86.

I seriously doubt they'll sell a manual for this but everything I posted so far is in the one we got a training.

ahhudgins
07-08-2009, 05:53 PM
JimN,
Thanks for you help, and everyone else as well. I ordered the manual from Discount Inboard Marine and I should have it in a few days. The problem is VERY intermittent but if it won’t fire I’m sure that I can find the problem once I have the manual. I’ve been repairing industrial electronics (CNC machines and PLC systems) for 25 years and I know how hard it is to diagnose a problem via phone, email, or message board. I’m going to check all of my relays and connections this week. I’m guessing it’s going to be a connection problem as you suggested or a bad relay. It may not fire up less than 10% of the time, but I know it won’t do it when I’m ready to test it. It will wait until I’m changing skiers in the middle of the lake!!
Thanks again.

JimN
07-08-2009, 10:12 PM
JimN,
Thanks for you help, and everyone else as well. I ordered the manual from Discount Inboard Marine and I should have it in a few days. The problem is VERY intermittent but if it wonít fire Iím sure that I can find the problem once I have the manual. Iíve been repairing industrial electronics (CNC machines and PLC systems) for 25 years and I know how hard it is to diagnose a problem via phone, email, or message board. Iím going to check all of my relays and connections this week. Iím guessing itís going to be a connection problem as you suggested or a bad relay. It may not fire up less than 10% of the time, but I know it wonít do it when Iím ready to test it. It will wait until Iím changing skiers in the middle of the lake!!
Thanks again.

Another thing you should check is the Ignition Control Module's ground inside the distributor. If that's corroded or the screws are a little loose, it'll do some weird things.