holley 4150 on marine power 5.7 electric choke plate wont fully open

[Billnet]

I have a holley 4150 double pumper with electric choke. I noticed that with the engine running and fully warmed up, the choke plate is only open 2/3 of the way. The electric choke has a vacuum line coming from the baseplate of the carb to a port under the choke housing. Also has a clean flowing intake port by the housing thats part of the choke assembly.

I'll list what I have checked out so far.

checked the voltage. verified 12.2 volts with the engine off and 14 volts with the engine running.

energized the choke but did not starting the engine. choke plate fully open after 3 minutes


I let the choke cool down and started engine. choke plate only goes open 2/3 of the way

I have repeated step 3 after changing the tension on the spring by rotating the choke for minimum tension but same 2/3 open.


I have checked all linkage and verified it all moves freely.


Wondering why it opens fully when not running but only 2/3 when running.


Do you think the vacuum line attached to the choke is preventing the plate from opening fully when running? It’s the only thing different than when I tested it and it fully opened when the engine was not running?

 

[Scott Danforth]

the double pumper may be too big of a carb for a 5.7

however there is no vacuum ports on marine carbs. there may be a heat riser choke tube.

Post a pic of the carb.

 

[jimmbo]

You checked the voltage at the choke, connected with engine running?


Marine carbs do have vacuum ports

 

[Billnet]

No Title

Here is the carb. It was stock on the engine. Its a 600cfm. Yes I checked the voltage while running to be 14 volts. 12.2 not running. The ports on this carb pull manifold vacuum. It has a PCV manifold vacuum port on the rear base plate and a vacuum port on the front base plate that pulls manifold vacuum and connects to the choke housing for air flow to prevent overheating

 

[jimmbo]

The air flow thru the choke housing is to operate the choke pull off so the engine can get enough air to run. Is there supposed to be a gasket under the black choke housing? If too much air is getting in the housing it will cool the bimetal. You might have to contact Holley for advice.

 

[HT32BSX115]

Wondering why it opens fully when not running but only 2/3 when running.

Howdy,


Did you adjust the choke a little more the "OPEN" direction to see if it will open further after fully warming up?

Try energizing the choke heating element (engine OFF) and after that 3 min, start the engine and see what it does. If it closes part way with the engine running adjust it a little more "OPEN".

Now having said that, I too have an electrically heated auto-choke on my Mercruiser 454. But since I only boat in warm weather, I disconnected it altogether and adjusted it fully OPEN permanently. It takes a couple of extra pumps on the accel pump initially starting but after warmup and running it's fine for the rest of the day.

My auto-choke has been disconnected since 2006. If I start the engine for the first time of the Season after sitting all winter, I usually pour a "splash" of gasoline into the carb so I don't have to crank a lot to fill the carb which is sometimes a little dry after sitting for 9 months.......After that, it's good for the entire Summer.

ymmv.....

Rick

 

[Billnet]

Thanks. The holley tech said to block the intake tube to the choke a little and that seemed to help.