Quick question regarding checking the timing.

[estame6]

1988 Sea Ray Weekender 300. Twin 5.7L 260 hp MIE Mercruisers. Not much room in front of the port engine to check the timing marks. I notice at the rear of the engine above the flywheel a large rubber cover and when removed shows top of the flywheel and starter teeth. Are there any markings that show TDC? I'm at home mulling my options over and I thought I would ask the question. Thanks...

 

[alldodge]

Are there any markings that show TDC?

Unless the prior owner added them, then No

The cover is there so a starter can be installed there instead of the engine block. This is only done on inboards, and depending on where the hole is determines if a standard or reverse rotation starter is used

 

[estame6]

Ha! Go figure, be too easy. I checked my timing and it advances nicely. I will be making some timing marks on flywheel or what can be seen easy, maybe a TDC, the inital setting and maybe a 18o. I'll have to check what the exact numbers are. Today I checked both my engines and they both moved the same on increased rpm's. I wanted to proof my Thunderbolt Electronic Module before I went further. My issue is not being able to get over approx 1400 rpm under load, at dockside rpm's increase nicely. C/O carb's between engines, replace dist cap and rotors, wires are in great shape but did check carefully that they go to the correct plug. The only thing I can think of now is the HT coil, thinking that plug resistance goes down under load maybe could be the culprit. I'll swap them over on the weekend. Any other suggestions would be appreciated.

 

[Bondo]

Any other suggestions would be appreciated.

Ayuh,.... Examine the Contents of the fuel filter for crud, 'n water, then pop on a new one,....

Most common cause of yer issue is poor fuel delivery,....

 

[estame6]

Ayuh,... Took your advice and purchased 2 Fuel/Water filters and fitting them today, will let you know.

I have often suspected condensation in the fuel tanks especially the last couple of years where I haven't topped them up.

2x 100 gallon tanks probably less than half so your post rang home..... Thanks,

 

[estame6]

Replaced fuel/water filers with same result, engine under load will not go over 1400 rpm. Cut open filters and were very clean with no sediment.

I have a large well and have tied off the bow and added extra spring lines and can apply reverse power in bursts quite effectively to check this problem.

Stbd engine at temp increasing the throttle in reverse fairly quickly will power up to 2500rpm for a brief second and then back to idle. This is the way it's always responded and this engine runs well. The port engine in the same situation, when it reaches 1400 just bogs down and as I increasing the throttle to full just sounds throaty with no more rpm's.

Everything on the top of the engine has been swapped over with the other including the q'jet. Timing checked and in spec's. I agree with Bondo and feel it is a fuel problem.

Yesterday I borrowed a fuel pressure tester kit and on starting the engine the 0-100 psi gauge didn't move. How accurate are these gauges at the 5 psi level? Due to the port engine starting and running up to temp perfectly I at least expected to see a few psi if the pump is the problem. Maybe the gauge wouldn't show just a trickle if this is what I'm getting.

Any thoughts on this would be appreciated...

 

[Bondo]

Ayuh,.... Ya need a zero to 15 psi or zero to 30 psi gauge to measure carb fuel pressure which oughta be 4 to 6 psi,....

 

[estame6]

I'm sure everyone getting tired of this problem. Ran engine this morning sucking fresh gas out of a gas can and same problem, not much over 1100rpm under light load, so it seems it's not a contaminated gas problem. I noticed while warming up the engine and then running it at 900rpm for 5 mins that it was slightly smoking which I hadn't noticed before. I have ordered a 0-15psi fuel gauge, will be here end of week but if the pressure is on the high side would this cause a rich mixture situation. What would cause high fuel pressure?

 

[alldodge]

Don't see it being to high of a pressure, if anything not enough pressure or a carb problem. The smoke your getting, if its rich then you should smell gas, if its oil not so much. But again if it was running rich it should rev up, it would be idling which would cause it to spit a spudder.

 

[NHGuy]

1400 rpm is where the primary fuel circuit is really coming on. When you test again stick a pen or a screwdriver in the choke of the bad motor to hold it open. If it's electric it might have not power. If it's heat actuated by intake manifold contact it could be bad.
Usually low fuel supply causes popping, you have a bog.
Did you really change the carbs? Sounds like a primary fuel circuit problem. But if the carb works on the other motor it's not.

 

[Pete104]

Yea, that cover is in the center of the flywheel hsg. Nothing to do starter location. Back then engines actually ran both ways! Right hand & Left hand. That was the end for Mercury with counter rotation (righty) because Bravo could go either way as well as any tranny they used. The marks, if any would be on the "flex plate". There should be a stainless pointer in there also. Up kind of high in bell looking flywheel hsg.
Being that old, it's gonna be a battle against rust that has built up!

 

[estame6]

Thanks Pete, If I had have looked closer there is a pointer and when I fired up the timing gun it pointed to the mark on the flywheel perfectly. I am assuming it is a tdc mark, so I'm going to have to adjust the timing as it seems to be retarded approx 5 degrees.

 

[estame6]

I timed both engines and the marks were both 8 degrees BTDC. Perfect way to set timing without having to hang over the front of the engine while running.
All problems solved, both engines run up to just over 4k at a nice plane.