88 merc 60 (2 carb, 3 cylinder)

[Asnarby]

Having a tough time with an 88 mercury 60, 3 cylinder, 2 carb engine.

Engine starts fast, but dies and will not hold revs. Sometimes I can almost get up on plane and then it bogs out and stalls.

New spark plugs
New diaphragm gasket kit installed
New fuel tank and hose
New inline filter on engine.

-Engine acts no different when I try to pump the prime bulb when taking off or trying to hold rpms in neutral.
- I have taken the cover off so I could see the carb inlets. Pumped the primer ball until it was stiff, no sign of leak and primer ball stayed stiff.

After running I took the plugs out and they all had fuel on them. The bottom one may have been slightly dirtier.

Any suggestions on where to look next would be greatly appreciated!

Thanks,
Andreas

 

[Asnarby]

Does anyone have any suggestions on where to go next?

 

[racerone]

As always post the actual compression values on your motor.

 

[Asnarby]

Shocked I left that out!

From top to bottom;
130, 128, 125

As always post the actual compression values on your motor.

 

[racerone]

Does spark jump a gap of 3/8" on each lead ?

 

[Asnarby]

Does spark jump a gap of 3/8" on each lead ?

When testing, I had consistent spark at 1/4”, intermittent between 1/4” and 3/8”, and I didn’t see any at all at 3/8”.

 

[Asnarby]

When testing, I had consistent spark at 1/4”, intermittent between 1/4” and 3/8”, and I didn’t see any at all at 3/8”.

It also seems to run slightly better cold, but still has issues.

 

[jimmbo]

Check all connections in the Ignition System for Tightness, and Corrosion. Spark needs to be Consistent, at 3/8"
You might have Dirt/Gum/Varnish in the Fuel Circuits in the Carb(s). While you replaced the Tank and Hose, the Hoses, between the Connector and the Carbs, might have Problems restricting Fuel Volume.

 

[Asnarby]

Check all connections in the Ignition System for Tightness, and Corrosion. Spark needs to be Consistent, at 3/8"
You might have Dirt/Gum/Varnish in the Fuel Circuits in the Carb(s). While you replaced the Tank and Hose, the Hoses, between the Connector and the Carbs, might have Problems restricting Fuel Volume.

Thanks for the advise! I haven’t changed any of the fuel lines that are right on the power head (only the main from the tank), I’ll see if I can change all of those.

I tried cranking the engine and noticed a bit of a fuel spitting forward.

Also, when I prime the bulb, it pumps up hard and holds pressure, no visible leaks.

Thanks!
Andreas

 

[Asnarby]

Does spark jump a gap of 3/8" on each lead ?

While home this time I had a week before I’d get a chance to run it so I decided to pull the two carbs and attempt to clean them. Gasket was damaged on 1 and I did notice some small debris when draining the fuel.

Where do people get repair kits for these? My local mercury dealer quoted me $210 for a single carb repair kit!

 

[racerone]

Clean the carburetors.----Make a new gasket.

 

[Asnarby]

Check all connections in the Ignition System for Tightness, and Corrosion. Spark needs to be Consistent, at 3/8"
You might have Dirt/Gum/Varnish in the Fuel Circuits in the Carb(s). While you replaced the Tank and Hose, the Hoses, between the Connector and the Carbs, might have Problems restricting Fuel Volume.

Update;

I changed all fuel lines on the power head, I put a new gasket kit in the fuel pump, I put one brand new coil in and also borrowed some used ones to try ( found two cracked badly).

Had carbs out and ultrasonically cleaned.

Put the boat in, fired right up. Let it idle to warm up a bit, gauge came up around 100f . When I took off, the boat stumbled a bit (likely need to adjust carbs more) and then planed off, I’d get some hesitation and it would start to die, back off throttle and it cleaned up, ran well at around 1/4-1/2 throttle. Did that a few times and a couple stalls. Fired right back up. Had the boat plane off, ran around half a mile over 4,000 rpms, sounded great, and then died. Couldn’t get it to start after. So disappointing!

 

[Asnarby]

how can I upload a video from my phone? It’s saying too large.

 

[Asnarby]

I figured out how to use a timing light today after the motor died. When cranking, very intermittent spark (top plug is on the brand new coil). An hour later I tried the middle plug. Perfect spark, tried the bottom, perfect, top now was fine too. I think when it starts to get warm it really acts up.

Staror? Trigger? Anything else to check? The cdi box is new last year.

Thanks,
andreas