Cold Start Trouble

[dgopetactical]

installed new carb, plugs wires , cap rotor, etc. stated last week vacumed tuned thecarb to directions, set electric choke to almost closed pos.(Cold)

when you let the engine sit for a day or 2 I have a hard time getting it to fire. it might try a time or 2 but mosly cranks. if I throtle it up it fires right up most of the time. any sugestions will help. I have been moving the choke adjustment around and see no difference. once it starts it runs fine and restarts instantly from then out. This is all on the driveway on muff taking to lake this weekend.
Denny

 

[imported_TheMan]

Re: Cold Start Trouble

Are you priming it with gas right after letting it sit for a day or two? A shot of fuel or two is pretty normal for it to start right up.. Its a carb not FI, so a little extra effort is often needed.

 

[Maclin]

Re: Cold Start Trouble

For I/O automotive-based carb engines......

The throttle needs to be moved forward past halfway and back to idle position at least once before starting in order to set the choke and squirt some fuel into the engine via the accelerator pump in the carb.

Even though the term "electric choke" or "automatic choke" sounds like it works with the key it still is a mechanical device that must be set manually via throttle action. The electric choke is called that because it uses an electric heating element to warm the choke and slowly pull the choke open during the engine's warmup cycle as the choke is needed less and less. The term automatic choke refers to the fact that the mechanical linkages are designed to set the choke via the throttle with no separate choke cable.

 

[Silvertip]

Re: Cold Start Trouble

The choke also needs to fully close on a stone cold engine. When the engine starts it will be pulled partially open and the choke heater opens it from there. If the choke doesn't close fully and you are not using the neutral throttle disconnect feature and pumping the throttle a couple times, you need to. Have someone show you how that works if you don't know how. Continue what you are doing (or not doing) and you will be spending money on a starter.

 

[180shabah]

Re: Cold Start Trouble

The choke does not need to be "set" by throttle action, however pumping the throttle does squirt a dose of raw gas into the intake. You need to verify that your are getting this squirt before turning the key. After a day or two it is possible that you don't have enough gas in the fuel bowl to start the engine, and you have to keep cranking until enough fuel is pumped to fill the carb.

Do this:
Before touching the key, remove the flame arestor and have an assistant pump the throttle while you look down the carb - is there a string stream of gas or just a trickle or nothing?

If there is not a strong stream - crank the engine for 3-4 seconds and pump it again - got gas, close it up and try to start normally. still no gas, crank for another 3-4 seconds and recheck. There definately should be gas in there now.

Also - if this gets more in depth we will need to know exactly what carb you have.

 

[Maclin]

Re: Cold Start Trouble

You are correct 180shabah, the choke plate will close without the throttle being moved, nothing to set manually by throttle movement. The "setting the choke" wording I had was describing the automotive thing with the fast idle, the fast idle won't set until the throttle is moved. I can take my brain out of the car but hard to get the car out of my brain sometimes. There should be no fast idle on the marine setup but as you mentioned the throttle movement is still needed to get the fuel shot into the intake from the accelerator pump circuit in the carb.

 

[Fishermark]

Re: Cold Start Trouble

I see from your signature line that you have an 87 Mercruiser 5.7 liter engine. the chances are good you have a quadrajet. If so, where did you get this "new carb?" A common problem with quadrajets is the fuel bowl leaking. The plug at the bottom of the fuel bowl should be epoxied closed.

You also need to do the above mentioned items as well.

 

[Lakester]

Re: Cold Start Trouble

installed new carb, plugs wires , cap rotor, etc. stated last week vacumed tuned thecarb to directions, set electric choke to almost closed pos.(Cold)

Denny

hello,

this does not make sense to me:

stated last week vacumed tuned thecarb to directions,

do u mean, started last week?

and used a vacuum guage per carb install instructions?

why did u change the carb? wondering.

why did u not change the fuel pump? is it elec or manual?

regards
lakester

 

[GaBoy]

Re: Cold Start Trouble

I had the same problem but after some time I found that if I pump the throttle 3 or 4 times then hold the throttle open and then turn the key and as soon as she fires back off the throttle immediately to neutral. She does just fine. And I have to do this hot or cold. I have 85' Merc GM 350/260hp.

 

[dgopetactical]

Re: Cold Start Trouble

I see from your signature line that you have an 87 Mercruiser 5.7 liter engine. the chances are good you have a quadrajet. If so, where did you get this "new carb?" A common problem with quadrajets is the fuel bowl leaking. The plug at the bottom of the fuel bowl should be epoxied closed.

You also need to do the above mentioned items as well.

This had a holley on from the original owner (street carb), It ran great but it was a street carb. I contacted holley and bought a marine match. The street carb always started instantly without pumping the throtle. with your help I figured out this carb does require pumping. So far so good.
thank you

 

[180shabah]

Re: Cold Start Trouble

I can take my brain out of the car but hard to get the car out of my brain sometimes.

Been there a time or two