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sk8salomon
08-27-2012, 09:27 PM
The craziest thing happend yesterday. I took a group of people out on the boat, picked them up at the dock, then took off down the lake only to find the boat would't go over 21 mph! speed control was off, no vibrations, felt normal rpm @ idle and starting. i pushed the throttle all the way down and nothing. i ran it down the lake for about 10 minutes, shut it off, floated around for a while, then retarted and same thing. floated around and idled some more, then took off and everything was back to normal. speed control works fine, throttle max rpm works as it should, etc etc. i had the dual fuel pump replaced about 3 years ago.

mikeg205
08-27-2012, 10:29 PM
I bet fuel pump again... :(

sk8salomon
08-27-2012, 11:30 PM
damn, that sucks. well, this time instead of buying the $500 unit, i'm going to replace the pump itself with the auto brand. did it to my buddy's X7 a few years ago and it's still running strong...maybe $95 for the pump.

skijwr
09-12-2012, 12:47 AM
sk8, Any update on the fuel pump issue ? any progress to find a fuel pump from auto parts store for around 100 bucks ? Thanks.

sk8salomon
09-12-2012, 06:07 AM
i went out last weekend, tooled around for about 3 hours and no problems. then on the way back to the dock it did it again. shut the key off, sat for about 2 minutes, started back up and had full throttle. i guess i just need to pull the pumps, put 12v to them and see which one f-s up. i'll post up the model number when i pull them out. thanks for checkin in.

zok14841
12-15-2013, 05:11 AM
Hello,

I had a similar problem last weekend. Went wakeboarding with my 1996 Prostar 190 and suddenly engine didn't want go over 2500rpm and sounded weird. I turned off the engine and started immediately again and everything back to normal, however a minute or so later again. So I had to shut down and restart the engine several times all the way back to the dock.

Changed fuel filter and spark plugs but no result. Can it be the optispark system or something with the computer?

Cheers
Roland

blackcreek
12-15-2013, 09:25 AM
Roland, I would check the inlet screen at the fuel pump. What sort of noise is the engine making? If it is a high pitched whine I would guess your fuel pump is clogged or going bad. There is no optispark on an indmar LT-1, it is a northstar system. Overheating will cause the motor to go into limp mode so check for that also.

JimN
12-15-2013, 09:36 AM
Roland, I would check the inlet screen at the fuel pump. What sort of noise is the engine making? If it is a high pitched whine I would guess your fuel pump is clogged or going bad. There is no optispark on an indmar LT-1, it is a northstar system. Overheating will cause the motor to go into limp mode so check for that also.

But RPM Reduction (the real name for what people call 'limp mode') limits the engine speed to 2000 RPM and it toggles the injector banks, so it won't run smoothly.

JimN
12-15-2013, 09:37 AM
To the OP- check the plug for the harness on the fuel pump. Also, check the ground wires at the rear of the engine.

blackcreek
12-15-2013, 10:35 AM
But RPM Reduction (the real name for what people call 'limp mode') limits the engine speed to 2000 RPM and it toggles the injector banks, so it won't run smoothly.

And you just wrote a long explanation of it a while ago. Did not catch the RPM diff.

zok14841
12-17-2013, 06:39 AM
Thanks for the reply. I checked all the cables bu couldn't find any fault s far. Still have to do the ground cables at rear. I also took off the fuel pump connector and cleaned it up. Had problems in the past but then engine did and didn't start at all until I wiggled the fuel pump connector.

Noticed that there is no optispark - so that cant be the problem

I tried to run the engine on the trailer again and it runs fine for about 5 min and then again suddenly when I pushed the throttle down it didn't go over 2800 and some white smoke came out of the exhaust. Engine makes a grumbling noise or so and feels like some cylinders are not firing. When I changed the spark plugs two on one side looked a bit black.

Again when I switch off the engine and restart everything back to normal engine sounds ok and rpm go over 3000 rpm until a few minutes later it loses power again. Temperature seems ok an I am running water from a hose through the engine when on the trailer.

I thought to get a mobile mechanic to have a look at it an connect a computer to maybe find a fault code, however not sure if car mechanic has the knowledge.??

JimN
12-17-2013, 07:09 AM
Thanks for the reply. I checked all the cables bu couldn't find any fault s far. Still have to do the ground cables at rear. I also took off the fuel pump connector and cleaned it up. Had problems in the past but then engine did and didn't start at all until I wiggled the fuel pump connector.

Noticed that there is no optispark - so that cant be the problem

I tried to run the engine on the trailer again and it runs fine for about 5 min and then again suddenly when I pushed the throttle down it didn't go over 2800 and some white smoke came out of the exhaust. Engine makes a grumbling noise or so and feels like some cylinders are not firing. When I changed the spark plugs two on one side looked a bit black.

Again when I switch off the engine and restart everything back to normal engine sounds ok and rpm go over 3000 rpm until a few minutes later it loses power again. Temperature seems ok an I am running water from a hose through the engine when on the trailer.

I thought to get a mobile mechanic to have a look at it an connect a computer to maybe find a fault code, however not sure if car mechanic has the knowledge.??

Black spark plugs isn't necessarily bad- marine engines tend to run richer than cars.

If power drops, ALWAYS check the fuel pressure first. Yours should be around 30 pounds, with negligible drops on hard acceleration. The problem with diagnosing this in Winter is that checking it on the trailer isn't valid- it's not under load, but if it drops when on the trailer, you know there's a problem. Look for blockage at the inlet screen and make sure the filter(s) are new. Also, check the anti-siphon valve at the tank and, since it's a '96, check the fuel pickup tube for blockage. The weird sound, rough run and white exhaust concern me- do a compression test.

The white exhaust- dense & white, or less dense? Dense, white exhaust may mean gasket failure or overheat. Do you run it in salt or brackish water?

zok14841
12-17-2013, 04:04 PM
Yes it runs in salt water here in Sydney and I had to replace the aluminium heads about 2 years ago as they were corroded and oil and water mixed. Since then no problem. No milky grease in the oil.

Here it is summer now and hot, just have it on a trailer when not in use. I guess I nd a fuel pressure gauge to test it? What is the inlet screen?

And as I said the weird thing is that it runs completely normal again for a few minutes when I turn off and restart the engine.

Can it be the fuel pump pums additiona fuel when you turn the key before starting the engine?

JimN
12-17-2013, 05:22 PM
Yes it runs in salt water here in Sydney and I had to replace the aluminium heads about 2 years ago as they were corroded and oil and water mixed. Since then no problem. No milky grease in the oil.

Here it is summer now and hot, just have it on a trailer when not in use. I guess I nd a fuel pressure gauge to test it? What is the inlet screen?

And as I said the weird thing is that it runs completely normal again for a few minutes when I turn off and restart the engine.

Can it be the fuel pump pums additiona fuel when you turn the key before starting the engine?

Do you flush the engine with fresh water when you pull it out? If you still have aluminum heads, it's strongly recommended.

The MAP, Throttle Position and Engine Coolant Temperature (ECT) sensors determine how much fuel is delivered while cranking- the MAP not only tells the ECM the vacuum, it also indicates barometric pressure in the brief time between turning the key to ON, then to Crank. The Baro reading is how the ECM compensates for altitude. The TPS will allow fuel delivery as long as it's not at WOT but if it fails, it will cause the ECM to default to 12% throttle position. If you always have hard start problems whne the temperature is high, open the throttle a little- if it starts immediately, the ECT may be faulty. If the resistance is measured, a reading of more than 900 Ohms at 70F/21C means it's out of range. If it reads a lot more, it's definitely bad.

Does the exhaust smell strongly of gasoline? If so, I would recommend checking into the MAP and ECT sensors.

zok14841
12-17-2013, 09:49 PM
Thanks again for the quick reply.

Yes , I am always flushing the engine with fresh water after use, however even though the heads went 2 years ago.

I will try to clean the whole fuel system and check the sensors. Because it goes straight back to normal after restarting the engine I think it might be something electrical or sensor related.

Do you think a car mechanic could help with a diagnostic computer which can be connected I guess?

blackcreek
12-17-2013, 09:59 PM
http://www.mastercraft.com/teamtalk/showthread.php?t=30935&highlight=fuel+pump&page=2 Hook up a fuel pressure tester to the test port on the top of the motor. When you turn the key on with the engine(LT-1) not running you should see around 43 PSI when the pump cycles on. With the engine running at idle you will see around 38 to 39. Wide open throttle will be 43 to 45 or so. Check your pump inlet and power supply if you get low readings. My fuel pump was clogged at the inlet screen as seen in the link. My 97 prostar did not have a pre pump fuel filter so I added one. My ECT sensor went out last year and would only read the same resistance at any temperature. The ect is very easy to check with the motor cold then hot. The fuel pressure is even easier to check with a fuel pressure tester. The fuel inlet screen is a bit tough to get at but the pump comes off with simple hand tools.

JimN
12-17-2013, 11:16 PM
Thanks again for the quick reply.

Yes , I am always flushing the engine with fresh water after use, however even though the heads went 2 years ago.

I will try to clean the whole fuel system and check the sensors. Because it goes straight back to normal after restarting the engine I think it might be something electrical or sensor related.

Do you think a car mechanic could help with a diagnostic computer which can be connected I guess?

They may be able to use their diagnostic computer, but the V-Tronics Tech 1 had a separate Marine cartridge. If they use Diacomp, they can probably get an adapter for the cable.

Do a wiggle test- start it and wiggle the fuel pump connector, the grounds at the rear of the engine, etc. If you hear anything change when you wiggle the wires, look at the terminals.

zok14841
12-19-2013, 06:43 PM
I had a car mechanic look at the engine yesterday as all marine mechanic were booked until mid Jan as it is our summer in in Australia.

He found that I had missing sparks from the 4 double coils, one wasn't sparking at all. So he recons its the core pack and module.

I tried to get one but that seems to be very hard as its not the car corvette part but I think an Indmar part, correct?

I try to track down Indmar and Mastercraft in Australia for help, no luck so far.

JimN
12-19-2013, 07:30 PM
I had a car mechanic look at the engine yesterday as all marine mechanic were booked until mid Jan as it is our summer in in Australia.

He found that I had missing sparks from the 4 double coils, one wasn't sparking at all. So he recons its the core pack and module.

I tried to get one but that seems to be very hard as its not the car corvette part but I think an Indmar part, correct?

I try to track down Indmar and Mastercraft in Australia for help, no luck so far.

Should be the same as any Northstar coil, like in a Buick LeSabre. Google the part number to verify.

1redTA
12-19-2013, 09:13 PM
Next time you put on heads have them hard anodized first for corrosion resistance

Jerseydave
12-19-2013, 09:22 PM
Just my $.02 but if the coil packs are suspect, look for carbon tracking near the coil terminals where each plug wire goes on. (carbon tracks look like black lines almost like human hair)

You could also run the engine at night and look for any spark jumping or arcing but that's a long shot.

mikeg205
12-19-2013, 10:34 PM
Also check module which coil packs are bolted to. Corrosion or loose connections to module could cause issue. Rockman here had issues and was traced to a connection on module. Other people had issues due to corrosion on on connections on coil packs etc.

All these parts are available from GM aftermarket sources.