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92 190 PS 04-27-2013 04:32 PM

92 Prostar 190 with 351 running rough question
92 Prostar with a 351 HO that I'm getting out for the first time this spring. Worked on it yesterday changing fluids and running in driveway and everything was great. Ran it for 15 minutes or so to get it up to temperature and again when I was done and everything worked well.

Today before changing plugs and doing a couple more finishing touches it is not running well. Starts quickly and runs as long as you give it gas. If you try to hold any RPM or idle it won't stay running. Pulled the fuel filter in the tank (On the end of the fuel line) and cleaned it. Changed the plugs and still no progress.

Looking for the next things I should check?

93Prostar190 04-27-2013 06:28 PM

Still running the original mechanical fuel pump?

Maybe the diaphragm let go ...... Any exhaust details? Whitish smoke?

92 190 PS 04-27-2013 09:44 PM

Yes still the original fuel pump. Any simple way to check the diaphragm?

As for smoke, don't notice anything out of the ordinary.

thatsmrmastercraft 04-27-2013 11:15 PM

Start with the basics:

New plugs are good....gapped correctly?
Points or electronic ignition?
What is the age and condition of the distributor cap and rotor?
Same goes for the spark plug wires.
What is the idle speed set at?
Is your electric choke fully open after about a minute?
How much old fuel in the tank and was it treated when you winterized?
Is timing correct?
Has the carb ever been rebuilt? Is it a 4160 or a 4010?

Once you get through that, I would look for a vacuum leak. Spray carb cleaner around the base of the carb with the engine running (use caution here as it's flammable). If your engine speeds up with the carb cleaner, you found your leak.

That should keep you busy for a while:rolleyes:

Kyle 04-28-2013 12:03 PM


92 190 PS 04-29-2013 08:49 AM

Just an update for anyone that has similar issues in the future.

Pulled the fuel filter out of the bowl on the fuel pump and replaced it. Pulled the two inlet tubes off the carb and flushed them. Sprayed some carb cleaner in through the carb a couple of times.

Re installed everything and now the boat runs great again. Guessing there was some dirt in the lines somewhere. Hoping to run the fuel I have in the boat ASAP and start with a fresh tank for spring.

92Prostar190 05-27-2014 03:14 PM

Realize I am responding to an old post but having the same issue on my 92. Got it out for first run after winter and ran great all weekend, that is until the last run of the day. At that point the boat started to lose speed and RPM and forced me to come to a stop. It never died and when I would accelerate again, all was good and it would run but then randomly lose all speed and come to a stop. Initial start-up was fine and idle was fine, though admittedly as the day went out, I noticed cold start each time we went out would require me to give it some gas in order to stay running.

I have read on here about spark plug changes, fuel pumps, etc. I did winterize it and treated the gas. Tried to run most of that old gas out before refueling. Did not do a tune-up this spring as I had done that last year.

Any thoughts based on this? I know there are many things to begin analyzing and I am not mechanically inclined. Boat does have perfect pass and therefore has the dial to set the right tension for the throttle cable. I did loosen that prior to last outing because I was noticing that unless I keep my hand on the throttle, I progressively lose speed as the throttle comes back toward idle. So I did wonder if that adjustment had anything to do with it.

93Prostar190 05-27-2014 03:23 PM

My quick thought is that the mechanical fuel pump is starting to go ... they lose pressure at high rpms and don't seem to affect idle at all ... I had one that was going bad and the kids could kneeboard (20 mph) .... but I could not slalom because the engine would starve for fuel ....

Mechanical fuel pump easy to get ( and my best guess ....

zekedog 05-27-2014 07:59 PM

Um...fuel filter out of the bowl on the fuel pump? Gonna have to go look at mine. Fuel filter in the tank? Man, I gotta start spending more time back on this forum.

92Prostar190 05-28-2014 11:51 PM

I wonder if given it is the first run of the season and I had some old gas with stabil in it and then I added new gas if I might be dealing with some issues there. Thoughts on adding the Startron product to the tank to reduce the phase separation I might be experiencing which in turn could be causing the issue>

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