Can't reach WOT on a calm day.

[AshleysRevenge]

This boat has almost been totally repowered.

Sunday was very calm no wind. So I tried running the boat up to it's WOT. Correct me if I am wrong but I believe it should be 4200-4600rpms. The boat would only run up to 4000 and then no more. RPMS do not stay steady ether. I wonder if that could be the friction in the throttle shifter?

The boat is 25ft cuddly cabin. Merc 260 alpha 1. 1.47gears 20hrs on motor and stern drive. Full 85gal gas tank full 35gal water tank. Two people Two coolers and one of those shade things 90 lbs. I'm only listing this stuff for a weight reference. Prop is 14.75"x15" 4 blade.

The boat use to have a 15"x17" 3 blade and I went to get it cleaned up and they said it would be better, given the application to go with a new 4 blade. They are both aluminum.

Also I don't know, but the boat seems to run rich. We were dining 25mph and just out of the blue the boat just died. Almost like I bumped the kill switch and wouldn't start for awhile. It seemed like it flooded it self out. We slightly closed the 1/4 fuel valve and didn't seem to have that problem again.

The carb is a brand new rebuild QJ 4 barrel. Could I be over-propped? Or just have to much weight? Maybe I need to tune something some where?

 

[AshleysRevenge]

The camshaft in this First Mate Marine. Is said to be a "upgrade" FMM told me on the phone that meant the cam was the type they put in RV's and it should make the HP around 275 v.s. 260. FMM directions say Readjust Valves after bringing engine to operating temperature the first time.

I didn't do that because I don't know how to do that properly. I know how to adjust the valves, but I don't have the specs on how.

 

[alldodge]

This boat has almost been totally repowered.

Sunday was very calm no wind. So I tried running the boat up to it's WOT. Correct me if I am wrong but I believe it should be 4200-4600rpms. The boat would only run up to 4000 and then no more. RPMS do not stay steady ether. I wonder if that could be the friction in the throttle shifter?

The boat is 25ft cuddly cabin. Merc 260 alpha 1. 1.47gears 20hrs on motor and stern drive. Full 85gal gas tank full 35gal water tank. Two people Two coolers and one of those shade things 90 lbs. I'm only listing this stuff for a weight reference. Prop is 14.75"x15" 4 blade.

The boat use to have a 15"x17" 3 blade and I went to get it cleaned up and they said it would be better, given the application to go with a new 4 blade. They are both aluminum.

I think your over propped, I would suggest putting your old props back on and see what happens.
WOT RPM 4200-4800 per manual 3
Dwell at 28 to 31 degrees
Timing 8 degrees BTDC

Also I don't know, but the boat seems to run rich. We were dining 25mph and just out of the blue the boat just died. Almost like I bumped the kill switch and wouldn't start for awhile. It seemed like it flooded it self out. We slightly closed the 1/4 fuel valve and didn't seem to have that problem again.

The carb is a brand new rebuild QJ 4 barrel. Could I be over-propped? Or just have to much weight? Maybe I need to tune something some where?

You closed down the fuel shut off valve, or something else? Even new carbs can start flooding do to something getting caught in the needle seat. Need to look down the throat of the carb while running to see if it is flooding, or pull some plugs and see if they are black or a good tan color. If you run your engine lean it will destroe it self. So cutting down the fuel is not something you want to do unless it is a must to get home

The camshaft in this First Mate Marine. Is said to be a "upgrade" FMM told me on the phone that meant the cam was the type they put in RV's and it should make the HP around 275 v.s. 260. FMM directions say Readjust Valves after bringing engine to operating temperature the first time.

I didn't do that because I don't know how to do that properly. I know how to adjust the valves, but I don't have the specs on how.

The First Mate is starting to sound like Gilligan. The cam that goes in your year engine is a truck cam, which is what it came with and also would be once which are used in other trucks like RV's. The engine should make a bit more HP because it was bored out.

You also have a hydraulic cam, and "IF" it was adjusted correctly it will not need to be re-adjusted. That said, the engine should have been run for timing to be set and testing. If any re-adjustment was needed FFM should have done it at that time.

 

[AshleysRevenge]

I forgot to mention I have 9-10 psi from the mechanical fuel pump. She is timed correctly.

We would never have know this (being overpriced) with the old motor seeing we could only get 2600rpm max. The guy who sold us the boat just said thats how she ran. LOL yeah right. The old prop is junk I really want a 4 blade 13"pitch if I can find one. For now I will get a 15x15 and a 15x17 and see how things go. Someone suggested getting them from overtone since they can be returned if resell able.

 

[Bondo]

I forgot to mention I have 9-10 psi from the mechanical fuel pump. She is timed correctly.

Ayuh,..... Ya oughta be seein' 4 to 6 psi,..... Put in a thicker gasket,.....

 

[AshleysRevenge]

Do you mean to get the pump away from the motor?

 

[Bondo]

Do you mean to get the pump away from the motor?

Ayuh,.... Thicker gasket, shorter stroke,...

 

[alldodge]

Could also do it with a pressure regulator. My question is there are not many "regular" pumps which will put out that much pressure, which one do you have?

 

[AshleysRevenge]

I don't know it came with the previous motor, maybe it is getting too much stroke. I have the gauge on it for now, until the kinks are worked out and then I am going to hard pipe/plumb the fuel line's. I would rather not change the pump if I don't have to but at this point I could care less, I've done every thing else I want it to be as close to being right as possible.

I have had someone else say a pressure regulator would help too. Someone that was on the boat while being tested.

How do I know what pump I have? All I know is what it is putting out psi wise.

 

[Fun Times]

How do I know what pump I have? All I know is what it is putting out psi wise.

Does the pump look like this, (take note of the gaskets) http://www.mercruiserparts.com/Show...=1077&bnbr=80&bdesc=FUEL+PUMP+AND+FUEL+FILTER

This your engine?
http://www.mercruiserparts.com/selectSerailRange.asp?doc_nbr=260++++GM+350+V-8+1982-1986

 

[AshleysRevenge]

Well that definitely looks like the fuel pump that I have. It would be a lot easier to put a regulator on there than to add gaskets hoping to get the pressure right.

Just to be clear here does the high psi mean that the carburetor is getting too much gas?

If I am over propped with a 15 pitch 4 blade prop which is the same thing as a three blade 17 pitch then shouldn't I be trying for A three blade 15 pitch in order to compensate for being over propped?

 

[alldodge]

Well that definitely looks like the fuel pump that I have. It would be a lot easier to put a regulator on there than to add gaskets hoping to get the pressure right.

Just to be clear here does the high psi mean that the carburetor is getting too much gas?

From your symptoms yes your getting to much gas. The needle valve in the carb is designed to handle up to about 7 to 8 psi. The pump is putting out so much pressure it is blowing pass the valve. Good thing with a regulator, if your pump starts to weaken later the regulator will keep it at what you set it at (suggest 6 psi).

If I am over propped with a 15 pitch 4 blade prop which is the same thing as a three blade 17 pitch then shouldn't I be trying for A three blade 15 pitch in order to compensate for being over propped?

No, a 15-4 blade is about the same as a 17-3 blade, but these are approximations. Every boat is different and two engines are different then one when it comes to prop calculations. My thought is either try a 14-4 blade (if you can find it) or 13-4 blade, or 17-3 blade for test

 

[AshleysRevenge]

I picked up a 16"x13p 3 blade, also a 15"x15p 3 blade. I'm going to try out the 13p first and see where my WOT is at this weekend.

I tried google for a pressure regulator and was unsuccessful. Can someone point me in the right direction on that?

 

[AshleysRevenge]

Yes I see some here on Iboats, not sure what I am looking at or exactly for...

 

[alldodge]

Yes I see some here on Iboats, not sure what I am looking at or exactly for...

Your looking for a 4 tp 9 psi regulator. I didn't find any on iboats which would work. Here are a couple links
http://www.jegs.com/p/JEGS-Performa...table-Fuel-Pressure-Regulator/989186/10002/-1
http://www.summitracing.com/parts/qft-30-803?seid=srese1&gclid=CMar7oKwlcYCFQ6OaQod-oIA8w
Hollet part number 12-803
https://www.holley.com/products/fue...regulators/carbureted_regulators/parts/12-803

 

[AshleysRevenge]

I got the Holley. Thanks AllDodge. I'll let you all know how it goes this weekend.

 

[AshleysRevenge]

Terrible that's how it went. Put the holly regulator on and got so frustrate with it not regulating, took it off. Some times it would hold at 4.5 psi and then back up to 9psi. It would seem that every time the pressure was high it would kill the engine. Since it remains around 9psi the motor seems like it is flooded all the time and flooded motors don't seem to like to run.

When the motor does start it, at it's own choosing cuts out completely and instantly, just like you hit the kill switch. It will run for different length of times and RPMS.

We sat at the dock for 3hrs until dark trying to figure this out.

I am going to try a few things tomorrow. I have a brand new extra carb laying around I am going to swap out, to rule out the carb. I am also going to run the carb currently in the boat straight off a can of gas. The current carb was just rebuilt, so I am wondering if all the fuel issues have fouled up the carb some how.

If the carb is fine I will probably go after the fuel pump with a thicker gasket, which was suggested earlier in this thread.

One other thing we tried to do a donut out from the dock and back and were half way successful. Half meaning we made it out under power until the motor quit and would not start again. Melissa ended up swimming the boat back in. Thank goodness there was no wind and very little current.

Anyway, when the motor quit in Fwd gear It sounded like there was something spinning in the out drive until shifted back to neutral. This happened twice. Any ideas on what that rotating noise might be the the motor is not running???

 

[Bondo]

Anyway, when the motor quit in Fwd gear It sounded like there was something spinning in the out drive until shifted back to neutral. This happened twice. Any ideas on what that rotating noise might be the the motor is not running???

Ayuh,.... That's the water pressure pushin' the prop, turnin' the prop shaft over the clutch dogs,.....

Completely normal,...

 

[alldodge]

Terrible that's how it went. Put the holly regulator on and got so frustrate with it not regulating, took it off. Some times it would hold at 4.5 psi and then back up to 9psi. It would seem that every time the pressure was high it would kill the engine. Since it remains around 9psi the motor seems like it is flooded all the time and flooded motors don't seem to like to run.

This doesn't make since, the regulator should not do that. The 9psi mechanical fuel pump is outside the range of normal. The flooding carb is not outside the norm. I'm leaning toward the carb float level is incorrect, or the seat/needle valve is defective. I would find another fuel pressure gauge

 

[AshleysRevenge]

I woke up Saturday morning and went out to work on the boat. I was going to try to start it so I could run freshwater through it. Once again noticed that the choke wasn't opening. Which I noticed the night before but I didn't have my voltmeter with me so I couldn't check it. To make a long story short I trace the wire not working all the way back up to the ignition switch which the screw on the ignition switch to the kill switch was loose. I tighten that up and she fired right up. Thank you AllDodge by telling me that it couldn't make sense that the regulator was not working. In the end we just couldn't run the boat long enough to actually get the regulator tuned in right. Now the regulator is in and keeping the PSI at 5.5 load or no load. Thank you for your advice I have a happy running boat. I'll have to do some more test drives to check the prop I can only get up to 4100 RPM this weekend.