Still have port engine problems!

[piperca]

Okay, I did a ton of work on the engines and I'm still having a problem with the port, not as bad, but still there.

I replaced all fuel lines, fuel pump on starboard, fuel/water separators, carb filters, removed all fittings from the tank to the carbs and cleaned everything ... even the pickups.

The problem now is that if I push the boat over 1500rpm, the port engine dies. At 1500, she'll last about 15-20 minutes then die. At harbor speed, 1100rpm, she might last all day.

When out of gear, I can bring the engine up to 2500-3000rpm and leave it there without a problem. As soon as I place it under load at that speed, she dies.

Carb rebuild?

I also have a weak alternator on that engine, would that cause any problems?

[californiadiver]

Only you know your boat and its prior history. I can tell you a few things to check but am no expert. Coils have done this to me before, yup a coil....More than once I have experienced a loss of power because of a failing coil. At low rpms i was fine. Cheap fix if thats the issue. How bout the secondary barrell in the carb, i think thats what it is called. Is the carb flooding, needle getting stuck? Its hard to tell sometimes because marine carbs flood into themselves, not onto the ground where you can smell it. Doesnt sound like water in the fuel, the seperator should have isloated that, and the new lines should have isolated the ping hole. Like I said, you know your boat, that is why I suggessted these things and let you think on it. good luck

[piperca]

As far as coils are concerned, I swapped the port with the starboard (one of the benefits of having twins), but the problem persisted. I am leaning towards the carb, but I'm not familiar enough with the operation of the carb to know what's going on ... wish I did! Hopefully someone who does will chime in and give me some advice.

[piperca]

I tracked down a place in La Habra, I-5 Automotive, that specialize in carbs. They have a rebuilt for $260, how does this sound. Here's a link to their site: http://www.i-5automotive.com/

Please let me know what you think.

Anyone used the Carb Shop in Costa Mesa?

[drippyskippy24]

do you have points? as for carb shop been there once the guy has a test motor he tunes your carb on, an seemed to be the king of q jet rebuilding. I .used to have a problem with points that would give me nightmares . had my distributor rebuilt with pretronics an recurved an never looked back!

[Saluki]

We had the same problem.
It's a timing issue.
She will run great without a load.
Put a load on her and she'd stahl out.

Put her in the water
Get up to 1200-1300 rpm
Loosen distributer clamp & slowly rotate one direction until it runs worse.
Then rotate back the other direction.
You'll hear the engine picking up speed and be able to set the timing dead nuts while under load.

Much more acurate than sitting on the driveway.

After timing is set, back it down to idle and reset the low idle throttle linkage to 750 rpm.

That should do it.

http://www.thecarbshop.com/
Yep, that's where we took Hanna's carb.
Damn good shop and well worth the big bucks you'll pay there.
But It'll get done right and turn around time is 24 hrs.

[piperca]

My distributors are Prestolite electronic upgrades too, no points to blame here. The caps and rotors were replaced about 10-15 hours ago, so all should be fine with that.

Brandon, I dropped you a PM.

[25 FB Skippy]

Sorry to hear you are still having problems.
Like some of the people above I have had issues with points or a bad Cap or rotor doing weird things.
Do you have points or are you electronic ignition??
How did the filters look when you changed them??
Have you replaced the spark plugs or wires lately??
Does the engine backfire or just have no power?
Do you have (1) fuel tank or (2) ? If you have (2) try switching fuel lines or buy a small outboard tank and run it off of that.
I have a extra complete marine distributor and a marine carb. if you want to try before throwing more money at parts hoping to fix the problem. The carb is 750 cfm Carter AFB, so it would be a little rich but would tell you if it was the carb or not.
If you would like some help you can call me @ (951) 315-5048 Robert

[25 FB Skippy]

After you changed the cap and rotor how did it run? I had a missed boxed rotor once and the engine would run fine for about 20 min. and then loose power and backfire. I tried all kinds off things and finally noticed the cap wasn't firing in the right spot.
Pull the cap and check to see were the carbon marks are on the cap and on the rotor. It should be centered on the firing pins ( or what ever you call them) for each cylinder in the cap.
Good luck!

[piperca]

Robert, thanks for the offer.

One tank and the filters looked fine, a little grime, but nothing major.

The distributors are upgraded to the Prestolite electronic style. When I changed the caps and rotors, I did so as regular maintenance. As far as I can remember the old ones looked fine.

Just curious; why would the engine run under load at lower rpm's than when at higher rpm's? I thought a timing issue would affect the entire powerband ... not questioning, just interested in the reason it's doing what it's doing.

I can run the engine at 3K rpm for as long as I want, but when a load is applied, that's when I have the problem.

[25 FB Skippy]

Not sure if this is all correct, but I will try to explain it the best I can. When the engine is under a load it changes the resistance the plugs have to spark against, so if your coil, cap, rotor, plugs or wires are weak they start having problems under load.
By what you have explained so far I think your problem is in the carb also but you should also check the complete ignition system.

[25 FB Skippy]

Check the new cap and rotor that is now on the motor.
Not the old one.