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Truck takes forever to start cold

76k5blazerr

76k5blazerr

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So my 76 blazer with an edelbrock 1406 takes a good 15-20 seconds to fire up when cold, even with the choke on. Why is this, hot starts it fires right up but if it sits overnight or for a few days it takes so long to fire up. Any help is appreciated. Thanks guys.
 
76k5blazerr said:
So my 76 blazer with an edelbrock 1406 takes a good 15-20 seconds to fire up when cold, even with the choke on. Why is this, hot starts it fires right up but if it sits overnight or for a few days it takes so long to fire up. Any help is appreciated. Thanks guys.
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There are a lot of potential reasons for your problem. Hot starts are very easy because so little fuel is required, the bowl is full, and gas hasn't had time to drain back. Evaporation of fuel from the bowl can happen, but usually takes a lot longer than overnight. Possible problems:

-Your choke is not operating or is not properly adjusted. The engine requires a significantly richer mixture when cold starting. This was my problem when I first bought the truck. Choke didn't work, every cold start would take about 10 seconds of cranking.

-You have a leak in the fuel system that is causing fuel to leave the lines. You may also have a bad diaphragm (mechanical pump) that is allowing fuel to leak into the engine, or a weak electrical pump that doesn't hold pressure.

-Your fuel bowl may be leaking. I'm not sure about Edelbrocks, but this problem is common on old Quadrajets, where fuel will leak into the intake.

Ignition/Engine issues--ignition problems, particularly those involving bad connections, can be temperature dependent. You may be getting poor or inconsistent spark when the engine is cold. Bad coils or ignition modules are common issues. Incorrect ignition timing/vacuum leaks can make a vehicle harder to start. Fouled or incorrectly gapped spark plugs can hinder starting, as can poor compression, weak battery, or any number of mechanical factors. Probably not your problem but may be a contributing factor.

-You may be flooding the engine. Generally with a properly functioning carburetor, a couple pushes on the pedal before starting is plenty. If the motor floods it can take some cranking before the excess fuel clears out. This can also occur if you're in a cold climate and icing on the throttle blades occurs.

That's all I have for now, I'm sure others will chime in. Just start with the easy stuff to check first and work your way down. Carburetors are pretty simple.
 
Start with the choke adjustment. Dead cold, snap the throttle once and check the choke plate...should be closed. If it is closed, good. If it's not it'll need adjusting. Don't try to start it yet.

Open the choke plate with your finger, and while looking down the carb snap the throttle again. Watch for a spray of fuel. If there is fuel in the bowl and the accelerator pump works you'll see a healthy spray of fuel. No fuel spray and you have some sort of drain back issue, or a problem with the accel pump.
 
^Yep. The choke is easy to check and the most likely cause of the problem. If by using tRusty's steps your carb/choke checks out, then your problem is elsewhere.
 
I went to a manual choke because of this and I can control the amount of choke and idle speed. my engine doesn't like the choke too much so its a fine line.
 
Ok thanks guys, I'll try Trustys steps in a little while and I'll let yall know what the results are.
 
Ok so I did what Trusty said to do and found that something is not working quite right on the choke, the fast idle arm thing on the driver side of the carb is not engaging on a cold start and the choke is not fully closing, even when I held the choke fully closed and pumped the gas twice, (there was a healthy spray of fuel) the truck still took its usuall 20 seconds to crank. Keep in mind this is after sitting in my 65 degree garage for only 48 hours. What next guys? Preciate the advice. Keep it comin!
 
Electric choke? Can you snap a pic of the carb from the passenger side?

A healthy shot of fuel takes care of a few things. You fuel bowl is not dry and the accel pump is working.

If this is an electric choke there is a round black deal on the side of the carb held on with three screws. Inside that black thing is a bi-metal spring that expands and rotates the the linkage when 12 volts is applied. What you need to do with a cold engine is snap the throttle, then loosen the screws a little.

If you look carefully you'll see some hash marks on the plastic housing. there should be one raised line on the aluminum housing it's screwed to. Make a note of which line is at the reference line, then rotate the black part one or two lines one direction. Snap the throttle again...if the choke is even more open rotate it back the other way. Don't make big adjustments. Try two lines, blip the throttle and see where the choke plate is at. Ideally it should just barely close. when you get it so that the choke plate just barely closes, tighten the screws and if you have a paint pen makr the line on the black housing with the paint pen for future reference.

When you get the choke set that way, pump the gas twice and turn the key. It should start almost immediately.

Gotta ask how the rest of the tune up items are? Spark plugs, wires, cap, rotor, timing...recent? a little worn? unknown? Has this cold start problem been recent or always or now getting worse?
 
Ok I'll try what your talking about with the choke adjustments, it is an electric choke. Also the spark plugs are new, I replaced them probably 2 months ago, the plug wires, cap and rotar all came on the motor I dropped in the truck and the PO said the plug wires weren't that old, I don't know about the cap and rotar. As for the timing, I timed it when I got it and set it at the factory spec. Which I think is like 8-12 BTDC. One more question for you, when you say snap/blip the throttle you mean to floor it once quickly right? If not, what do you mean? And the cold start problem seems to be since I have had the motor, didn't seem bad when it was in the other guys truck. Thoughts?
 
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76k5blazerr said:
Ok I'll try what your talking about with the choke adjustments, it is an electric choke. Also the spark plugs are new, I replaced them probably 2 months ago, the plug wires, cap and rotar all came on the motor I dropped in the truck and the PO said the plug wires weren't that old, I don't know about the cap and rotar. As for the timing, I timed it when I got it and set it at the factory spec. Which I think is like 8-12 BTDC. One more question for you, when you say snap/blip the throttle you mean to floor it once quickly right? If not, what do you mean? And the cold start problem seems to be since I have had the motor, didn't seem bad when it was in the other guys truck. Thoughts?
Click to expand...

Yes thats what he means.


Ive fought the choke opening seemingly normal but the fast idle not operating properly too. They can be a pain in the ass some times.
 
When I say snap/blip the throttle I mean give it a quick snap which you can do by hand. This takes pressure off all the linkages and sets the choke, and should land the throttle stop on the high idle cam.

Another good thing to try is a bit of carb cleaner on the linkages in case any are a bit gummy and sticking...
 
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