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Worthing skier
05-23-2010, 03:28 AM
I have a 1993 prostar 190 with a 285 hp inmar (carb), starts and idles fine ,revs up fine stactic at the dock , hole shot is good , but at 2500 rpm plus it has no pull , there is just lots on induction noise, it does not feel like any ht brake down or misfire , also on a coupe of occasions the power has instantly come bach while driving at 2500 rpm .
Plugs, carb rebuild were done 30 hrs ago .
Just pulled the carb off , all looks good , not dirt etc.
I am have a few thoughts on which way to go but dont want to flod it with parts to fine the fault ,
Does the distrubtor have and mechinical advance , could the vac secendaries or secondary side of the carb cause this , also coil .

Help

Philip
05-23-2010, 12:07 PM
Hello!

The problem is that the engine got to little gas. Just change the fuel filter and the engine should work just fine. For example you can use Sierra 18-7983-1, nice price with water separator.
(http://www.sierramarine.com/filtration-fuelfilters.html)

God luck and regards
/Philip

glassmaster
05-23-2010, 04:28 PM
Definitely sounds like the engine is starving for gas to me could be the filter but if it has a Holley I would check out the accelerator "squirter" needle valve it might be sticking. As long as you don't run the engine over 5000-5500 rpm you really don't need it in there and it can be removed.
I don't think it would be your distributor or timing or you would not have any power at hole shot. You can always check it with a timing light. After the timing is set lock down the distributor and keep your light on and rev it up the timing marks should advance but no more than 32-34 degrees
Or you can send Jimn a Pm and I'm sure he can help you out.

oldairboater
05-23-2010, 06:37 PM
Had a similar problem last week with my 93 Prostar. Mine was either needle valve and float level or secondaries. Messed with float needle valve and lubed/ worked secondaries on bench. Carb working fine now. Boat does 43 mph at 4200 rpm. WOT.

thatsmrmastercraft
05-23-2010, 10:03 PM
Definitely sounds like the engine is starving for gas to me could be the filter but if it has a Holley I would check out the accelerator "squirter" needle valve it might be sticking. As long as you don't run the engine over 5000-5500 rpm you really don't need it in there and it can be removed.
I don't think it would be your distributor or timing or you would not have any power at hole shot. You can always check it with a timing light. After the timing is set lock down the distributor and keep your light on and rev it up the timing marks should advance but no more than 32-34 degrees
Or you can send Jimn a Pm and I'm sure he can help you out.

Wow, where do I start with this. Likely to fuel supply issue. Replacing the fuel filter would be a good choice.

It isn't the accelerator pump (accelerator "squirter"?) as hole shot would be terrible.

It isn't the power valve (accelerator "squirter" needle valve?) as when they blow out they go to full rich and it would run like crap.

Incidentally, the power valve opens based on reaching a predetermined level of vacuum - not RPM, and you do need it when the engine is under load even at low RPM (think pulling a fat chick on a toob)

Checking mechanical advance would be a good idea.

Ruptured secondary diaphragm?

So would ensuring good battery connections.

The condition of spark plugs, dist. cap & rotor, plug wires and coil are all possibilities.

If the spark arrestor were thoroughly gunked up it could have this effect.

How did it work during the last 30 hours since the carb work?

Worthing skier
05-24-2010, 06:47 PM
Hi All

Thanks for all the ideas, have just put a rebuild kit in it , not had a chance to go back to the lake to fit it and test it.
However the old power valve did seam as if the diaphram was not holding so thats as a maybe ,accelerator squirters have always worked realy well .
Fuel filter was replaced 30 hrs previous , did not find any dirt in the carb .
Will take a timing light to check the mech advance as thats a strong possablity , checked the secondary diaphram , thats fine .
Plugs (ngk) have done 30 hrs , unsure as to the work the rest of the Ht system has done but it appears okay (no corrision on plug lead ends and dis cap) , it does not feel like an ht misfire .
Boat ran fine for the last 30 hrs after the last rebuild.
Battery terminals all been cleaned with wire brush and carefully greased , as have engine earth starter terminals etc .

Will post the outcome of the carb and what i find with the mech advance .

Kevin

thatsmrmastercraft
05-24-2010, 07:31 PM
You can check the power valve by holding the body and trying to turn the small end. If it turns - it is bad. Good luck sorting this out. Keep eliminating stuff and you have to eventually find what is wrong.

Worthing skier
05-25-2010, 05:37 PM
Just got back from the lake , carb fitted and runs fine .
I think it was down to the power valve or something going on the secondary side float bowl , however when I overhalled the carb I did find the secondary throttle stop siezed I did try a little heat but would not move so I could not adjust it so although it is okay now I feel I may have another issue later on , however butterflys do not appear to lock in the bore .
Checked the mech advance all free however was very dry so gave it a lube ,also did notice that the lighter gauge return spring was very rusty , does anyone know were these can be bought from ?.
Flashed the timing light on it , did see 20 advance but I am unsure if i had the probe on no 1 cylinder (had it on drivers side frt), it that no 1 .

Thanks again to you all

Kevin

Worthing skier
05-25-2010, 05:48 PM
Pic of my m/c p/s 190

Jorski
05-25-2010, 10:27 PM
(think pulling a fat chick on a toob)


I will not !:cool: