PDA

View Full Version : Engine Issues


russfortin
10-11-2007, 01:24 AM
I have a '87 prostar 190 that doesnt seem to want to run correctly. It starts fine and idles great but as soon as you put it in gear, it tries to quit on you. pumping the throttle keeps is going but still isnt right. After its in gear and "pumped" it runs just fine. A couple other things is that even though i have tuned the mixture correctly, at full speed there's white smoke coming out of the exhaust as if its too rich. also it may just be my lack of optimism but it seems like i dont have as much power as i had at the beginning of the season. Top speed 39-40:(

probably seems like a lot but theres a good chance its all related and any help would be appreciated.

Chicago190
10-11-2007, 01:29 AM
Sorry I can't help but white smoke is usually not associated with running rich. Black smoke = fuel, white = water, blue = oil.

bigmac
10-11-2007, 08:27 AM
White smoke might be water in the fuel (steam). A cracked water jacket might cause such thing, or some other abnormal connection between cylinders and combustion chamber.

russfortin
10-11-2007, 10:00 PM
my flame arrestor is pretty dirty (pieces of old belt and such in it) which could be the cause. maybe the engine isnt getting enough air in the mixture? i've ordered a new one, hope that fixes it but im also changing the fuel filter and inspecting the lines for debris

russfortin
10-11-2007, 10:01 PM
on the topic of the white smoke thing too, it smells heavily of gas so thats what lead me to belive its running a little rich. it doesnt do it at idle or cruise speeds, just at WOT where would be the best location to check for water? thanks

rektek
10-11-2007, 10:07 PM
sounds like a carb power valve issue, what's the history of the carb ?
any misfiring ? overheating ? or water in the fuel tank ?

russfortin
10-11-2007, 10:15 PM
i bought the carb bebuilt from a shop that specializes in that. the boat doesnt misfire. i havent been able to check for water in the tank yet but i'll get on that asap. doesnt seem like the issue though. with no load on the engine it goes in gear with no issues, in the water it sputters unless you pump the throttle everyother throttle setting works without any sputtering.

what would i have to do to correct a power valve issue?

WTRSK1R
10-11-2007, 11:30 PM
on the topic of the white smoke thing too, it smells heavily of gas so thats what lead me to belive its running a little rich. it doesnt do it at idle or cruise speeds, just at WOT where would be the best location to check for water? thanks

If you suspect a crack in the water jacket, the head, or a leaky head gasket a compression test would be the easiest way to detect it. If all cylinders are within about 10% of each other, then you are probably ok. I am not certain what the expected value is, but around 120 psi seems to stick in my head.

Steve

Laurel_Lake_Skier
10-11-2007, 11:34 PM
You may have a bad head gasket or crack in a head or block that is letting water into a cylinder. It would be worth doing a compression test or if possible a cylinder leakdown test. As was mentioned, white smoke would be consistent with steam while an overly rich mixture would be black in color. One thing to note is that if you are running in cool temps, some steam coming out with the exhaust is pretty normal. As far as needing to pump the throttle, your choke may not be set correctly or your idle speed may be low. Idle should be 600-800 rpm in gear.

rektek
10-11-2007, 11:42 PM
see if the shop will loan you a different carb ?
faulty head gaskets, cracks etc. don't always show up in compression tests. Typically if I have concern about compression I'll do a cold compression test and cylinder leak down test. then try again with a warm engine.

the fact that your boat runs fine until you apply a load makes me think carb or ignition. what's the history of your ignition system ?