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flya750
09-09-2009, 11:41 PM
Hello All,

Well after 12 years with my beloved PS190 w/LT1 740 hrs..... I had my first issue on the water tonight?

It wasn't a major issue..but after skiing and a ride around the lake. We were coming back to load the boat back on the trailer and the boat wouldn't go over 3k RPM? The throttle was doing weird things? If you power up to 3k RPM and let go of the throttle .... the RPM would climb ever so slowly? Like 50-100 RPM increase? It was weird.

The engine seemed to run fine... no sputtering at lower RPM so I made it back in okay.


My fuel gauge is not working (recent sending unit failure) but I had a full tank of gas when I started out the evening ski ride?

I'm wondering if some thing in the cruise control or the throttle linkage is causing the problem? The cruise was turned off @ the time. Maybe a clogged fuel filter? The boat ran fine as long as you didn't want to go over 3k RPM...no over heating indication either?

I used the boat a lot this past weekend and it performed flawlessly... I was even thinking how 12 years of care free boating was too good to be true....(Maybe I shouldn't have jinks myself ? ;) ;)

Any ideas?

Prostar19
09-10-2009, 10:05 AM
not sure if this is it but my 1996 190 with the LT1. There was a small inline filter behind the center cushion on the back seat just on top of the fuel tank. It was clogged and the boat would not run well at all. It would idle fine but would not stay at higher RPM's

87MCProstar
09-10-2009, 10:19 AM
Does the marine LT1 have a 'normal' style distriubtor? I had an auto 94 LT1 with their weird optispark distributor, and I had an issue like this one and that was the culprit.

Ski-me
09-10-2009, 10:28 AM
I'd start with new thermostats (160 and 142) and then fuel filters. Be sure to clean the screen at the inlet (bottom) of your fuel pump. I found all kinds of stuff in there. Mine was bogging down around those rpms......as soon as I got the correct t-stats in there, I was fixed.

Good starting point anyways.

Ski-me
09-10-2009, 10:36 AM
Here is what I found at my fuel pump inlet screen....:o

flya750
09-10-2009, 10:39 AM
It's an LT1 with the northstar ignition system if that helps..

Yeah.. it sure does seem like a fuel issue....

Thanks guys...

flya750
09-10-2009, 10:56 AM
Curious? How would a thermostat effect the lack of acceleration past 3k RPM?


I'd start with new thermostats (160 and 142) and then fuel filters. Be sure to clean the screen at the inlet (bottom) of your fuel pump. I found all kinds of stuff in there. Mine was bogging down around those rpms......as soon as I got the correct t-stats in there, I was fixed.

Good starting point anyways.

flya750
09-10-2009, 10:57 AM
Really... Hmm... I've never changed that filter in 12 years.. Didn't know it was there? Thanks.


not sure if this is it but my 1996 190 with the LT1. There was a small inline filter behind the center cushion on the back seat just on top of the fuel tank. It was clogged and the boat would not run well at all. It would idle fine but would not stay at higher RPM's

Ski-me
09-10-2009, 11:16 AM
Curious? How would a thermostat effect the lack of acceleration past 3k RPM?

Here is some good reading with the thermostat.

http://www.mastercraft.com/teamtalk/showthread.php?t=32390

If the t-stat gets stuck or malfunctions, it really messes with the engine performance. However, my temp guage was moving around and yours sounds like it is not. May or may not be the problem but good insurance if you haven't changed it in awhile.......

flya750
09-16-2009, 01:30 AM
Hey Ski-Me...

I think you get the blue ribbon for proper diagnosis of my RPM reduction issue. I have basically deduced that my problem is a clogged fuel pump inlet screen just like you posted.

Recently, I noticed a high pitch whine and I didn't know what it was?.... well the whine is most likely due to the fuel pump not getting enough fuel. I guess the pumps make a racket when they are starved?

So tomorrow I hope to remove the pump and clean any debris out. I'll post back with an update.

flya750
09-24-2009, 11:44 PM
Anyone know where I can find the presta valve on my PS190 '97 w/lt1?

I need to remove the fuel pump for cleaning and possible replacement.. I was told I had to first release the pressure by using the presta valve under a red cap? I can see no red cap?

Will I find it on the pump?

Thrall
09-25-2009, 09:27 AM
There's a shrader valve on the fuel rail (tire valve). Just release the fuel pressure there.

JimN
09-25-2009, 09:30 AM
Anyone know where I can find the presta valve on my PS190 '97 w/lt1?

I need to remove the fuel pump for cleaning and possible replacement.. I was told I had to first release the pressure by using the presta valve under a red cap? I can see no red cap?

Will I find it on the pump?

It's a black cap and it's a Shrader valve. A Presta valve is like the skinny one on a bicycle tire.

When you pull the pump, look at the screen on hte intake end and remove any fibers or other stuff before replacement. That alone can fix your problem.

JimN
09-25-2009, 09:36 AM
Curious? How would a thermostat effect the lack of acceleration past 3k RPM?

If the thermostat maintains an operating temperature that's far too high, the ECT (Engine Coolant Temperature) sensor will go out of normal range and the ECM will only alternately trigger the injector banks, and lower RPM makes the motor run cooler.

NOTE- THIS SHOULD NEVER BE SEEN AS "LIMP-HOME MODE" IN A BOAT!!!!!!!!. If it happens with a boat that uses raw water cooling, it should be shut off immediately, the trouble found and repaired and the motor should be allowed to cool to a normal range before starting, in order to avoid thermal shock to the castings. If the cause of the overheat can't be repaired quickly, the boat should be towed in, especially with an LT-1, which has aluminum heads and they don't tolerate overheats well.

flya750
09-25-2009, 12:54 PM
It's a black cap and it's a Shrader valve. A Presta valve is like the skinny one on a bicycle tire.

When you pull the pump, look at the screen on hte intake end and remove any fibers or other stuff before replacement. That alone can fix your problem.

Alright.. Thanks.. I remember seeing something like that last night when I was looking and lining the tools that I will need for the project.

I will clean the Pump and see if my high pitch WHINE goes away. But I've had this hi pitch whine for a few seasons so I may have damaged my pump?

I have no problem changing out the pump and giving me the piece of mind that a day on the water will not be sacraficed for being cheap.

JimN
09-25-2009, 03:14 PM
Alright.. Thanks.. I remember seeing something like that last night when I was looking and lining the tools that I will need for the project.

I will clean the Pump and see if my high pitch WHINE goes away. But I've had this hi pitch whine for a few seasons so I may have damaged my pump?

I have no problem changing out the pump and giving me the piece of mind that a day on the water will not be sacraficed for being cheap.

It's a pretty durable pump- check the pressure at Key On/Engine Off, idle, 2000 RPM and WOT to be sure. If it stays at 30 lbs without dipping more than a pound or so at all of these, I'd leave it in. We have had several threads about fuel pressure gauges here, too but if you need one that won't break the bank, Sears and Autozone sell one that has a purge valve and a clear line that you can use to collect some gas for taking a sample. O'Reilly sells the same one, I think and all of them sell it for about $35.