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I am playing with a 79 k5 Blazer. It has a quadrajet on it and now it does not want to start without priming the carb. It sat for a year and never had this problem prior to being parked. Fuel pump is working ok, and once it runs for about 30 seconds, it starts fine, but if it sits for a day or more, I can only seem to get it running by again priming the carb. Any suggestions as to why this is and what I can look at.
Thanks
Chris
 

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The biggest problem you are probably having is that during the long sitting time the components inside the carburator dried out and may have cracked. Mainly the needle and possible the accel pump. It may also have left a heavy residue in the float bowl as well. About the only fix is to clean carb thoughly and install new parts. Q jets can be difficult if you are not use to working on them. About anytime you leave a vehicle sit for long periods of time problems can happen better to start them occactionally to keep them running properly. In this case not using it did more damage then using it.
 

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cdiedrick said:
I am playing with a 79 k5 Blazer. It has a quadrajet on it and now it does not want to start without priming the carb. It sat for a year and never had this problem prior to being parked. Fuel pump is working ok, and once it runs for about 30 seconds, it starts fine, but if it sits for a day or more, I can only seem to get it running by again priming the carb. Any suggestions as to why this is and what I can look at.
Thanks
Chris

Quads are simple to work on. :mwink:

Today's gas gets pretty NON-vaporous after about 3-6 months.

First I would do this = Drain the old gas out first and then put 4 bottles of carb/FI cleaner in about 5 gallons of fresh gas in the tank. And run it through to cut the sludge. Drive it around the block 40 times. (You don't want to walk far...LOL) Don't add more fuel until you are afraid of running out. Give the stuff time to work.

If it runs fairly well after starting, and you continue to have the problem, I would look toward the fuel pump.
 

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Sounds like the gas is syphoning back out. There is a check valve in the filter that has probably dried out.....Cleaning the carb wont hurt either if it sat quite a while.
 

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Check for a blocked charcoal canister - I know it's cold there right now and these things mostly play up hot, but it can cause the symptoms you describe. BTW it was 41.5c here today with a heavy cloud of smoke from the bushfires.
 

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Qaudrajet

Yeah I have too Go with cdiedrick on this . Throttle pump is weak . Not givin her enough of a squirt , after sittin for awhile . As too fuel additives ? I dont use them ! Here In Peoples communist republic of Calif . We have oxygenated fuel . Use Alcohol too Oxygenate gasoline . This stuff dry's out and eat's Rubber real fast ! Im bettin it's throttle Pump, weak , leaky not holdin a prime or pickin it up from the bowl . Sean
 
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