Stalling and Starting problems

[amplay]

I have a 1998 Mercruiser 5.0 Alpha 1 Gen 2 engine. Last fall I replaced the fuel pump and filter due to stalling issues. This spring I find I am having more stalling issues. As a test, I put in a can of Sea Foam and run in my slip 30 minutes at 1800 RPM, and then 20 minutes at 800 idle. No stalling at all.

Last week I idled out of the Marina (about 15 minutes), went full power up to 4000 RPM, and it ran great. When I powered down quickly to idle, it stalled. I then had continual starting and stalling problems, barely limping back to my slip.

Does anybody have any suggestions?

 

[alldodge]

I have a 1998 Mercruiser 5.0 Alpha 1 Gen 2 engine. Last fall I replaced the fuel pump and filter due to stalling issues. This spring I find I am having more stalling issues. As a test, I put in a can of Sea Foam and run in my slip 30 minutes at 1800 RPM, and then 20 minutes at 800 idle. No stalling at all.

Last week I idled out of the Marina (about 15 minutes), went full power up to 4000 RPM, and it ran great. When I powered down quickly to idle, it stalled. I then had continual starting and stalling problems, barely limping back to my slip.

Does anybody have any suggestions?

Need more info about the motor, have a serial number?
Being a 98 I'm thinking it might be a TKS carb

 

[Merccoper]

Hey amplay. I had the same sort of problem last year. Would idle ok, troll speed ok but when I go wide open it would stall out then hard to start. Once I got it started again, the same thing would happen all over again.
Im almost positive it was water in the gas. I put a full can seafoam in the tank. It took about 20 minutes of running it (stalling, starting, running) before it finally ran ok. I can’t say for certain it was water, but that was my best guess.
(turns out I had a bad o-ring on the gas cap and rain was getting in)

good luck in your search.

 

[amplay]

Need more info about the motor, have a serial number?
Being a 98 I'm thinking it might be a TKS carb

The S/N is OL045552. Old school Carb

 

[amplay]

Carburator

 

[nola mike]

Fuel issue until proven otherwise. Did you change/check the fuel filter?

 

[amplay]

Fuel filter and pump replaced last September

 

[nola mike]

Fuel filter and pump replaced last September

Time to check the filter again

 

[airshot]

Had a similiar issue a few years back on my I/O. Run great at speed and choppy water, but slow speed and idle along with starting was an issue. Minevturned out to be water in the fuel, check your water seperator, if you dont have one, get one. As it turned out the water was comming in thru the vent!! Previous owner replaced the rubber hose but failed to create an upper loop to prevent water cooming in the vent from running into the tank. Once I added that loop, no more water in the tank. Can't say this is your issue, but it sure sounds familiar......

 

[QBhoy]

2 things.
1 it’s almost odds on to be a fuel thing
2 full throttle shouldn’t be 4000 rpm. It should be usually 4400-4800 on a carb motor like this. Generally anyway. Only getting 4000 rpm at full throttle would indicate a very harsh strain on the engine. Not good for her at all.

 

[amplay]

You are being more precise than I intended, I just meant that I was running at a high RPM and was doing fine.

 

[amplay]

What is the best additive if its water in the gas?

 

[QBhoy]

What is the best additive if its water in the gas?

Ok. No worries. Apologies for that. To be honest, the truthful and absolute answer is to get rid of the fuel you have really. Known it far too often to cause issues if it’s just treated or diluted with fresh fuel. Especially with carb engines. The carb often needs to be dealt with just after or sometime along the way after such a thing. Sometimes get lucky though.

 

[amplay]

thanks for the advice

 

[airshot]

Do you have a water separator filter? This will show you if you have water in your fuel.

 

[dubs283]

Does anybody have any suggestions?

When was the last full tune up?

FYI there is no fuel additive that can alter the quality of present fuel in a positive way i.e. make fuel fresh/good again. Best practice is to stabilize fresh fuel in the system especially if it's known to be unused for longer periods

 

[alldodge]

Have you looked down the throat of the carb when its stalling to see if its flooding?
If not flooding pump the throttle to see if fuel is squirting
Choke full open?

 

[amplay]

thanks guys. I'll go out there today and see what I can see

 

[Scott06]

thanks guys. I'll go out there today and see what I can see

It looks like the carb was replaced or at least stripped and rebuilt as an OEM mercarb would be painted black.

Was this replaced to correct this condition or for another reason?

Would agree you likely have a fuel supply issue. Would check down carb as mentioned take fuel filter off and dump contents into container to see what it looks like

 

[amplay]

It looks like the carb was replaced or at least stripped and rebuilt as an OEM mercarb would be painted black.

Was this replaced to correct this condition or for another reason?

Would agree you likely have a fuel supply issue. Would check down carb as mentioned take fuel filter off and dump contents into container to see what it looks like

Took the filter off and gas was clean, but there was a little dirt at the bottom of the jar I poured it into. Started the engine, goosed it until it died, and looked into the carburetor and saw a puddle of gas. What causes this?