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pkskier
03-24-2012, 11:37 PM
My '87 TriStar has a problem that I'm not sure what is causing it. Under load I am experiencing a loss of power and rpms. It is like it is fuel starved, could this be the fuel pump going bad? I replaced the distributor cap and rotor this weekend and I am still having the same problem. All suggestion are welcome.

sleeporbutter
03-25-2012, 01:31 AM
If you think it's fuel starved, have you checked the fuel filter. I'm not familiar with your specific model, but that's where I would start... If you have a mechanical fuel pump it has been my experience they either work or they don't, no in between.

oldairboater
03-25-2012, 07:32 AM
Don't waste money just changing parts. Trouble shoot it. Check and see if you are getting enough fuel. If it isn't a fuel pump problem or fuel filter. Could be something as simple as a plugged tank vent to a carburetor not opening up. Check your carburetor. I see that you changed out your distributor cap and rotor but why? Timing?

Kyle
03-25-2012, 10:10 AM
Your secondaries may not be opening and fuel may not be getting dumped in. I would find a way to watch the fuel spray into the carb while someone drives the boat at wot. It may be a simple float sticking. If you take a can of starter fluid and spray it when you have your power loss then you can start with finding the problem without spending a whole lot of cash.

I seriously doubt it is a fuel pump

How old is fuel water separator?

How old is the carb and has it ever been rebuilt.

If you are just starting your season I would be willing to bet the carb has a problem and the fuel sitting in it for months did not help the issue. It probably caused the issue.


Did these problems happen on the old cap and rotor. If not make sure the cap does not have a hair line crack in it. Also if you don't have electronic ignition check your points with a file or Emory cloth

pkskier
03-25-2012, 02:05 PM
Okay I need to give more info, I was trying to not be long winded. I replaced the cap and rotor this weekend because there was pitting on the rotor and distributor cap contacts. Yes the problem was happening with the old rotor and cap. I also replaced the water/fuel separator this weekend. When we put the boat in the water yesterday I took off up to 35-36 MPH and came back with no problem. Then I pick my wife up and we drove to where we normally ski at about 30 MPH took 5 minutes. Still no problems. I get ready to ski we take off and after about 6 cuts the boat bogs down. I get back in the boat, accelerate out of the hole, no problems, after about 2 minutes of running hard it bogs down again. You can back off the throttle and it catches back up. Idles fine no problem. Did this a couple more times same problem and it died once but started right back up. Idled around for a while and then decided to run some more. Ran at 2100 RPM with no problems until about 20 minutes of running at 2100.

The carburetor is 2 years old and has not been rebuilt. When I de-winterized I had a fuel leak and the front fuel bowl bolts were loose, tightened up and the leak stop. Don't know what the bolts were loose, no leaks the last time out last year or when I winterized it.

I do not think it is the fuel pump it is too inconsistent and my experience with a mechanical pump is it is either good or bad as mentioned before.

It definitely feels like a fuel starvation problem. I was wondering if the anti-siphon valve in the tank could be causing the problem, but I don't know why it doesn't do from the start.

Any suggestions.

Sorry to be so long winded.

D3skier
03-25-2012, 02:17 PM
almost wonder if it could be a loose/bad ground. Just had same issue with my Audi and spent 2 weeks troubleshooting and found a corroded ground wire

Kyle
03-25-2012, 10:06 PM
That sounds like an electrical problem. Make sure the alternator wires are tight and not corroded. Check connections at the starter too. Check coil connections.

Make sure the battery is fully charged too.


My boat does the same thing when I've been hard on the stereo all day and my batteries are drained the boat will run exactly how you described.

pkskier
03-25-2012, 10:58 PM
Thanks D3skier and Kyle you could be very right. The first time we went out I had not charged the battery over the winter like I normally do and it could not start the boat. I charged it but not fully and then yesterday I had no battery because I left my depth finder on for 3 weeks and had to charge it again. Neither time did I get the battery fully charged. I will go up to PK one night this week and bring it home and charge and then next weekend check all the necessary connections and clean them. Once again thanks.