4.3 Merc Idle Issues after Impeller Replacement

[Steamin Seaman]

i recently replaced my impeller and changed my lower unit gear oil. i put the muffs on her and she fired up no big deal. i let her idle for about a half an hour, then decided to open the throttle a little to push some gas through, as she sat a long time. when i opened the throttle just a little, she died... i repeated the process three times and decided to ask for advice... what gives? she is a 2008 Tahoe Q7i with a 4.3 mercruiser turn key start. serial number is not on exhaust plate. the intake manifold has 6M 125522422 on it and the out drive has serial 1A222219. Any Ideas???

 

[alldodge]

The TKS carbs have been an issue over the years. So the engine starts and idles fine, and it will go in and out of gear without issue, correct?

The issue is when the boat is in the water and you give it more then an idle it dies. Has the fuel filter been changed? Also there is a screen (item 29) at the carb entrance which also needs to be cleaned.

http://www.mercruiserparts.com/bam/subassembly/31493/12833/80

 

[Steamin Seaman]

When I check that, there is no or little back pressure when I pull that?

 

[Steamin Seaman]

I assume it goes into gear relatively easy. I only had it on the water once. It ran great for a few minutes then crapped out on me. That's when it all began.

 

[alldodge]

When I check that, there is no or little back pressure when I pull that?

If you mean there was little or no pressure when the filter was pulled, this is as it should be. If you meant that the filter was not full, then this is an issue. I'm also assuming you do have a spin-on fuel filter which looks like an oil filter.

I assume it goes into gear relatively easy. I only had it on the water once. It ran great for a few minutes then crapped out on me. That's when it all began.

If the motor dies when it is shifted into gear then it may be the shift interrupter, but if it does go into gear but won't run then there is a lack of fuel issue.

 

[Steamin Seaman]

there didnt seem to be any fuel in the filter (#29) when i pulled it off and cleaned it. it also seemed fairly clean, but i ran Carb/Choke cleaner through it for about 5 seconds on each side, then reinstalled it. started right up and idled fine for a while.

 

[Steamin Seaman]

i am going to take it to water today to do some checks. will repost when i am on the water...

 

[alldodge]

Not having any on #29 is ok, but wonder if the fuel filter (canister type) was full

 

[Steamin Seaman]

Got everything put back together. Fuel leaked from the brass fitting into #12 at a fast drip pace. Tightened several times to get to stop. Was there a grommet between the two, or is it a metal to metal flare? I ended up stripping the brass, it is such a soft bolt.

 

[alldodge]

The gas line is flared and mates with the one on the carb. There is another gasket on the nut which covers the screen. If its leaking at the fuel line fitting, it needs to be removed and see if it can be repaired. Look for burrs

 

[Steamin Seaman]

As of last night, the drop is about 1 drip every 5 minutes or so. Super slow. Thanks for all your help.

 

[fredcollett]

Had the same issues. With a 2008. 4.3. TKS. Carb
Replace carb with a new carb. With a electric choke. Fixed all my fuel problems. Boat runs great
About 300.00. On. eBay.

 

[Rick Stephens]

As of last night, the drop is about 1 drip every 5 minutes or so. Super slow. Thanks for all your help.

No leaks can be tolerated in a boat. No where for the fumes to go since they are heavier than air and the bilge is basically a bucket. Doesn't take all that much to build up a possible explosion hazard.

 

[alldodge]

No leaks can be tolerated in a boat. No where for the fumes to go since they are heavier than air and the bilge is basically a bucket. Doesn't take all that much to build up a possible explosion hazard.

Agree the leak needs to be stopped completely

 

[Jmunk]

Enclosed bilges are no place for a leak of any kind.

 

[Fed]

With flared pipes alignment is everything and I also flatly refuse to go near any pipe fitting without a proper pipe spanner.