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Kdmann64 07-02-2014 09:28 PM

01 xstar started running rough and hard to start.
I just bought an 01 xstar has 470 hours. Ran fine on test drive. Today filled it up with 93 octane, sea foam and blue stabil, went to lake today and pulled youth group from church around on a tube. Half way through the day the boat cut off while idling, then was hard to start. It did this the rest if the day, sometimes idle was fine other times it cut off and didn't want to crank back with out giving it a lot if throttle.
Where do I start? Fuel? Carb? Plugs?
I think I want to put new plugs in what the parts store plug number ?

MC25 07-02-2014 09:57 PM

Your 01 doesn't have a carb. lol Why did you put all those fuel additives in there?

mikeg205 07-02-2014 10:06 PM

Which engine do you have?

Simple first

Bad gas? Check engine light turn on?

When was fuel filter changed last? if good...

Check TPS (throttle position sensor) - connection may be loose or TPS bad.
Check MAP (Map sensor) make sure tube connected

Moving on -
Check fuel pressure - no carb either TBI or MPI fuel injection
In tank Fuel pump? pump could be failing.

Kdmann64 07-02-2014 10:27 PM

No check engine light. I thought it had a carb, don't know why. Just looked it and appears to be EFI. Now you guys see what you set working with. Speak slow and use small words. 5.7L TBI V-DR Y2K-MC PIT/N
Model 957214
I guess it could be bad gas from the station. But it's a pretty good station. Should I run regular. Pi always put ethanol treatment in everything and when ever I buy a new boat I usually run a can of seas foam though it.
I looked around and found a vent line in the valve cover get came loose. And a plug on the I guess the main harness plugged into. Itching but can't find where it does.
I see a fuel line on top with a black cap and fitting I assume where I can check pressure. I can do they tomorrow. No idea on fuel filter.

mikeg205 07-02-2014 10:37 PM

Okay let's rule out bad gas... no biggy on 93 plus additives.

TPS Sensor is on the TBI housing where fuel injectors - google GM TPS and look at images. Do the same for MAP.

If your not familiar with these components you could be chasing a lot of things down and spending $$$ for nothing.

If your not mechanically inclined get reading...

BG1772 07-03-2014 07:41 AM

If it is mainly ruining rough at idle, I would check the IAC (idle air control). If it is dirty it can stick causing the engine to run rough at idle.

Is this an LTR 330? If so the TPS and IAC are right next to each other by the air filter.

dcphoto 07-03-2014 09:03 AM

Common mistake which would be the easiest possible fix - make sure the kill switch key is firmly in place and putting good pressure on the actual switch. Amateur hour for sure on that one but happens!

Kdmann64 07-04-2014 12:26 PM

Checked the kill switch it seems fine, I replaced plugs yeasterday And cranked it in the driveway. I let it run for a few minutes and it seemed to idle fine but it didn't start the other day until we had been on the lake for a few hours. I'll try to take it Sunday and try it out.

CantRepeat 07-04-2014 03:27 PM

Kill switch is either work or no work. It won't make hard start or poor running.

swatguy 07-04-2014 08:52 PM

I am surprised no one said fuel pump yet. Another place to check.

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