C30 hard start

[rmotoman]

I would check if the choke is closing all the way for cold start. Press your accelerator to the floor once then take off the air cleaner lid to see if the choke is all the way closed. If not then check if linkage is gummed up or the bi metal is not closing the choke.

Rick

 

[olyman]

I would check if the choke is closing all the way for cold start. Press your accelerator to the floor once then take off the air cleaner lid to see if the choke is all the way closed. If not then check if linkage is gummed up or the bi metal is not closing the choke.

Rick

x's many--like said--hit the pedal, then pull the air filter, and check the plate is closed, just may need to readjust the choke plate--esp since you said runs fine when warm---

 

[Streblerm]

You didn't say whether it was a heat or electric choke. It does sound like it isn't closing all the way. It may just need adjusted. From the factory the element and cover is riveted in. the replacements usually have screws.

if you turn the cover i believe clockwise, it should tighten the choke spring. You need to turn it until there is just enough tension to close the choke, if it isn't already. Then if the choke doesn't come all the way off when warm, you need to replace the bi-metallic spring. I don't think they are too expensive.

Usually the cover is indexed so you can tell where it was/needs to go. You will probably have to drill the rivets to adjust it.

 

[RON58]

Pick up a manual choke cable kit for a few bucks. Slam it on and be done messing with it. I'm jealous,wish I had a truck like that.

 

[Ash wacker]

After you get the choke adjusted so it closes you should make sure the vacuum choke puller is working and adjusted properly.

 

[fishercat]

you can have one!

Pick up a manual choke cable kit for a few bucks. Slam it on and be done messing with it. I'm jealous,wish I had a truck like that.

i have one i'll sell you!

 

[mini14]

id do a compression check on a cylinder from each side, if its choking ok and strong spark, the only thing left cauzing a hard start on a cold engine is leaky head gaskets, valve seats and rings.

 

[ShoerFast]

Hello,
The choke plate appears to be closing all the way when the accelerator is pressed. Any other possibilities? Thanks again.

Just my $0.02 cents worth, but if you have a few different drivers for this truck, your better off keeping the auto-choke, as there the same start every time when their working right. If you have other carb issues and you put a manual-choke in it, you will still have cold start problems.

Bet I done a thousand overhauls to Q-Jets, good carbs, if it has not had a kit in awhile, OH it just cause, air-leaks in the base-center is one reason, a weak acc-pump is another reason both will give you cold start issues.

Chokes that lose there adjustment over time, if you roll the housing to give it more choke, it may not come-off as soon as you want, or might not come all the way off,,,, replace the choke bi-spring and your life will be easier.

If you adjust a weak choke just to close on a room-temp carb the vacuum of the engine may pull the choke open while cranking and not give you enough cold-start fuel.

Fix the real problem, and also give er a good tune up, the money you spend making it run right will not cost the amount of problems it could cost.

 

[RON58]

Didnt you say it runs very well after ya get her going? Seems like a simple fix to me. Making it much more difficult than ya need too.Choke cable. hey fishercat, what do ya got?PM me buddy

 

[Ash wacker]

If the choke spring is weak the downdraft of the engine turning over could pull the choke open. If the accelarator pump is working right a couple pumps on the gas pedal would be like putting gas down the front two barrels. You have to watch it cold and have someone turn it over and see what is going on with the front butterfly.

 

[ShoerFast]

After time, all Q-jets welsh plugs (well-plugs) leak, dumping all the fuel from the carb right down the intake.

Cold starting an engine with an empty carb needs a lot of cranking just to fill the carb, hard on starters , batteries and alternators, as well as washes some of the oil off the cylinder walls and saturates the oil.

In a good carb kit (NAPA Echland) will have a plug that fits into the base-socket where the welsh-plugs fit, that plug slows/stops the leak, for another reason to overhaul.

Fallowing every adjustment to a 'T' in the kit's instruction is a must for a place to start. Getting everything clean and well blown out is easy, a good spray-can of carb kleener with a straw will do a fair job in a pinch.

There are a couple tricks, like just pushing the acc-pump level pin 'in' just enough to get the lever out is a good way to slip the top off,,,, and helps putting it back together.

Q-Jets are a lot of fun, can produce a lot of power and are extremely reliably as carbs go.

There is no way I would put in choke cable, the choke it's self is not always the problem with a cold start problem.

Tap the net for some pointers, and have fun!

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[ShoerFast]

Hello,
I would like to try priming the carb, but to be honest, I'm not sure where the bowl vent is, in order to put a few drops of fuel in. Is it the "pipe" rising out of the bowl cover just in front of the choke plate? Thanks.

The need to prime the carb will be fixed by putting in a choke cable, I mean a good carb kit.

But if you dump about half a soda-can full of gas right down the hole where the secondary metering rods are you will fill the bowl.

 

[Kansas]

Just my $0.02 cents worth, but if you have a few different drivers for this truck, your better off keeping the auto-choke, as there the same start every time when their working right. If you have other carb issues and you put a manual-choke in it, you will still have cold start problems.

Bet I done a thousand overhauls to Q-Jets, good carbs, if it has not had a kit in awhile, OH it just cause, air-leaks in the base-center is one reason, a weak acc-pump is another reason both will give you cold start issues.

Chokes that lose there adjustment over time, if you roll the housing to give it more choke, it may not come-off as soon as you want, or might not come all the way off,,,, replace the choke bi-spring and your life will be easier.

If you adjust a weak choke just to close on a room-temp carb the vacuum of the engine may pull the choke open while cranking and not give you enough cold-start fuel.

Fix the real problem, and also give er a good tune up, the money you spend making it run right will not cost the amount of problems it could cost.

Best answer so far by far!

Q-Jet is argueably one of the best carbs made for production imo its the best and as shoe said its more than likely a bad base gasket or gummed up linkage or a plain old tune-up parts problem.

My advice is check the front 2 mounting bolts they are ALWAYS too tight since johnny local garage usually thinks since its a 5/16 bolt it needs 20 ftlbs of torque and it warps the pizz out of the carb top where the primary idle transfer ports and accel pump passages are sealed with the gasket/carb top and causes all kinds of driveabillity problems.

Since fuel cant be metered properly with a gasket air leak (with the top warped) the accel pump slots are not closed to the venturi very well either, it usually just dribbles down the bore if you look inside when moving the throttle. The tops can be straightened over a vice with a strainght edge and a mallet very carefully!

Spray carb cleaner is good to clean plates and linkage but always use air to remove all traces of it and the varnish or it will just re-congeal and make it worse. also dont spray any in the pull-off its just a rubber diaphram and will get ate up by the spray, actually just replace it since its the most important part of that carb in the first place you want a good one going into winter even if it is working right now it could be original equipment and will fail sooner or later and cause major driveabillity issues on moderate to heavy acceleration.

Definately stay away from any add on choke kit you will hate yourself a properly set and adjusted carb auto choke and good ignition parts thats the best. hth



Kansas

 

[ShoerFast]

Hello,
Is that the "larger" hole that protrudes up, just in front of the choke plate? Thanks for all of your help. Everyone else as well.

The gas would get there from that hole, but you would be a better pourer then i am, that hole is what, a 1/4" ?

You see the area just behind the air-filter stud-hole? (just ahead of the center of the secondary air-vain?)

 

[ShoerFast]

Right behind the choke plate?

Yep.

To say right down the center would be close, but just behind the air-filter stud, between those two cast air-walls , right down over the tops of the of the secondary metering rods.

 

[Kansas]

One more thing I just remembered about hard starts cold is if its got an early fuel filter w/o the check valve or someone has pulled the one out that supposed to be there it will loose its prime overnight and may struggle right off to run because of the return on the fuel pump the fuel will run right back to the tank when the engine is shut off the carb can be short of fuel.

Sorry about the carb school explaination I posted earlier just keep in mind to not over do the front bolts if you pull it off to check the base gasket or replace the pull off.

Kansas

 

[ShoerFast]

Thanks. I'll try pouring some gas in next time, just to see if it helps. Is changing the choke spring tricky, or is it pretty straight-forward. Thanks again.

Very straight-forward.

Index the spring between the forks if it has them (as opposed to the spring riding on just one side the choke linkage)

If the original is riveted on, just drill out the rivet and use the hardware with the new choke.

If you have a different/better cold start after priming it look for the numbers on the side the carb to get the right kit (and choke).

If you do happen to OH the carb, about 90% of all Q-Jets in bow-tie engines gain a little from stretching the primary metering spring a little (just like you would do for a click ball-point that had a soggy 'click') and give it a little more timing then what the book says.

Here is another vid, good as it shows really how eazy they are to work on.

*The 'fuel well' should not have fuel in it, part included in a kit. :48 (1:30 of the vid, use a kit from NAPA and be done with that.)

* At 4:00 he points out the secondary adjustment point, some read the kit instructions and lose-it when they read it, once you see it you will understand it. Nailing this adjustment is the nuts of a gooood running Q-Jet if you like power.

*4:50, forget that check ball and you get to 'do it again' , as the acc-pump will not work.

*5:15 He calls it a power-valve, or the main metering rods and spring, vacuum pulls the needle jets down/closed lean, the spring fights the vacuum up/open rich. Give the spring a little pull, if it's an 1 1/4 - 1 1/2" long, stretch it to about 1 3/4 - 2" long (like a click ball-point pen) It won't cost you gas mileage as the vacuum always wins, but you will get a lot more throttle response and a crisper acceleration, If this adjustment is perfect, it's hard to tell if the acc-pump fails.

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His guy has done this before....

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There are a lot of people that like the Q-jet, just a few that don't understand it, tons of info in the web.

 

[Kansas]

After time, all Q-jets welsh plugs (well-plugs) leak, dumping all the fuel from the carb right down the intake.

Sorry but only the early carbs had exposed welch plugs and even the enclosed ones that happen to seep dont cause any problem because there isnt any where for the fuel to go. The later carbs like this truck would have are enclosed, GM fixed it late 70s ish.

Kansas

 

[ShoerFast]

Sorry but only the early carbs had exposed welch plugs and even the enclosed ones that happen to seep dont cause any problem because there isnt any where for the fuel to go. The later carbs like this truck would have are enclosed, GM fixed it late 70s ish.

Kansas

Maybe? Guess Catfish will find out.

GM had a ton of problems using what ever came out of the warehouse, the 80's were the worst. These carbs were even made by Carter when Rochester could not keep up. Carter only made the welsh plug version that I knew of.

When the first Dodges that used Q-Jets (360+ engines) in the 80's , they all had problems, mostly air-leakages, but you never knew what Q-Jet you were going to get.

 

[streeter]

Sorry but only the early carbs had exposed welch plugs and even the enclosed ones that happen to seep dont cause any problem because there isnt any where for the fuel to go. The later carbs like this truck would have are enclosed, GM fixed it late 70s ish.

Kansas

True, BUT, the damn things leak fuel out over time and cause hard starts. The problem with them is you have to crank the vehicle over to refill the carb @a minute or 2, then pump the pedal to give it some gas and set the choke, then it will start.

To me (25 year mechanic), the carb needs overhaul and the trick is to use JB weld on the plugs so they do not leak. You can also just crank it for a minute or 2, then hit the peddle, leave the starter cool (@ 2 minutes) then try to start it. It should start.