Chysler 115hp bogging/killing at WOT

[Scry0402]

Hi All,

Greetings from the land of 10,000 lakes. I hope someone might be able to offer some suggestions about possibly things I’ve overlooked in trying to solve an issue with my 115hp Chrysler (motor # 1159H8B).

The Brief History:
Two months ago, distributor rotor broke off distributor shaft while at WOT. Motor killed instantly. Found distributor off a running Chrysler 105hp 4 cylinder. Swapped entire distributors with broken to running one.
Now motor runs, idles well, can do ¼ throttle, maybe up to ½ throttle.
WOT throttle from a dead stop results in motor hitting on all 4 for a short period, quickly fades (bogs), then wants to kill. All in about 20 yards or less. Motor stays running if you bring the throttle back.

Items I’ve checked:
-Upon reassembly, set timing according to instructions outlined by the “mweverett” youtube channel.
TDC is correct, motor is timed to 32 degrees, arch on distributor pulley lines with curve of flywheel at TDC.
-First time out after repair noticed bottom carb was leaking gas heavily. Have since pulled both carbs. Found each needle stuck in the “up” position where it was not resting on fuel bowl tab. Corrected that. Needles are still in good condition (new a couple seasons ago).
-Blew carbs out with cleaner & compressed air, set floats to 13/32”.
-Changed plugs to NGK BUH’s.
-Changed fuel line to clear so we could see gas pumping
-Replaced primer bulb to eliminate that as a cause

Important observations:
-Squeezing primer bulb when bogging does not appear to help this issue.
-Volume of gas being sucked into motor when throttle is at WOT does not change from idle/trolling speed
-Gas does not seem to be pulled consistently. Some gets pulled up, then theres a break. Some more, and then a break, etc….

Things other folks have said to evaluate:
-Boat uses two portable red tanks. Could click on connector be bad? Symptoms of a bad connector?
-Some have said rebuild fuel pump and/or fuel pump diaphragm? If that was bad wouldn’t squeezing ball have noticeable impact?

Just baffling, seems like air is getting into the system and starving the engine. Motor ran fine at WOT prior to this distributor issue happening. Ever since, can’t seem to get it figured out.

Any additional guidance or suggestions is greatly appreciated.

Thanks,

Ryan

 

[Nordin]

Start with checking and change the fuel pump diaphragm.
A little rip or hole in the diaphrgam would flood the cylinder that runs the fuel pump.

 

[WinnerCougar74]

I solved a problem with my chrysler 135hp by changing the fuel pump diaphragm. It would idle ok and ran ok at WOT (not prefect) but stumbled badly starting at 2000rpms on up to 3500rpms then it would kick in. It's starting to do it again so I probably need to replace the fuel pump diaphragm again. It's been about a year. Very easy job. I always wonder about all the check valves in the fuel pump but the rebuild kits don't come with them. I think I paid $18

 

[The Force power]

I always wonder about all the check valves in the fuel pump but the rebuild kits don't come with them. I think I paid $18

What is in the kits you buy? that should be part of the kit

 

[WinnerCougar74]

https://www.wholesalemarine.com/mercury-fuel-pump-kit-by-sierra-15377.html

Sounds like there better ones? Cool.

 

[WinnerCougar74]

Oops, no links i guess. Here is a pic. Looks like these are available on iboats.com

 

[The Force power]

Sorry...Yes, I was thinking of the Square style

 

[jerryjerry05]

The older fuel pumps with the diaphragm shaped like
the figure 8
The check valves, they hardly EVER went bad.
In 35 years I saw one that had fallen apart and yet it
still worked?? Was changing the diaphragm as SOP
and the valve fell out in pieces, yet still worked???

You could have a bad fuel line connector(has a rubber seal)
The Ethanol and additives that get put in the fuel can melt
the old rubber??
Or a bad diaphragm in the pump??

Try running without the hood??