Rochester Quadrajet Help

[twoskies]

1972 C10, 350/4 bolt
had a new fuel pump and new filter at the carburetor installed
original fuel pump would cut out /spring was broken
seemed to fix that issue
mechanical fuel pump

now having another issue, truck starts ok, runs ok most of the time, does try to idle down, it will die if you let it, but after it warms up and you shut it off, you have to push pedal all the way to floor to start , like its flooded

used to start up barely spin when warm

was checking today and in the picture, the black rubber cap with yellow marks, when i changed it, fuel was coming out, is this normal ?

might just go with a new edelbrock 1406 if i need a new carburetor

Thanks

[Getter-Done]

Sounds like the float is stuck open.
That is the first thing I would check.













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[mr.mud1]

hi,sounds like it is flooding?did the carb come apart?float set to high,possibly some crap stuck in the needle and seat if you were changing filters?is the filter installed in the correct direction?that isn't the correct carb for a 72 engine,it's a later carb,the 5th digit in the numbers on the drivers side of the carb back by the secondaries will tell you what year engine it was originally on.i always have better luck with the old quadrajets but that one you have should run well too.

[lil hoodlum]

I bought a remanufactured Quadrajet from National Carburetors a month ago. It was only $229.95 + 100.00 core charge. Installed it on the motor and after a little "tweaking" was running fine. Carburetor was Rochester 4MV.

I also bought remanufactured quadrajet from Summit racing but it would not run correctly out of the box. It was also around the $350 price range.

[Rich72C10]

one thing to check, if you haven't already, to see if you have contaminants in your fuel. Say like crap in your tank.

I only bring this up as this was my problem. After I bought my truck, my brother rebuilt the engine / transmission, including rebuilding the carb. After I went to go get it, it started do so a lot of what you are talking about. He pulled the carb (which is a Rochester Quadrajet like yours) and it was full of sediment. The tank was pulled, cleaned and lined at a radiator shop. Fixed that problem 100%.


Oh, the PO put on a 78 QJet Carter. I got a matching number Qjet Rochester off ebay for my 72 Truck and I have sent that off to https://quadrajetpower.com/ to be fully worked on and tweaking it. Though I am not expecting it before the end of April or sometime in May. The guy is crazy backed up

[twoskies]

Thanks

Sorry, the motor is not the same as the truck
motor is a 1979 ElCamino motor
the carb has never been adjusted, the covers for the air/fuel are still there

the fuel filter was changed with the fuel pump

ill pull the carb off tomorrow and check for junk or float

[BigBird05]

You replaced the fuel pump? I have read a lot of threads on here about replacement fuel pumps putting out to much fuel pressure.

[mr.mud1]

hi,no need to be sorry,if the adjustment plugs are there in place,the carb has likely never been apart and the float is probably set correctly but it could also be pretty dirty in there.as Richard said,his tank was full of trash so in order to keep the carb clean,the tank has to be clean.if you don't know what kind of shape your tank is in that might be a place to look.a trick i've used on the road when i had a flooding problem and nothing to work with for tools,go buy a can of fuel system cleaner,dump it in the gas,get the engine running with a moderate RPM and tap with a dead blow or rubber hammer on the front of the carb,right around that big 1 inch nut where the fuel line goes in,sometimes you get lucky and whatever is holding the needle open,will pass through.temporary fix but it would be worth a try to see if you make any progress.good luck.we'll be waiting for an update.Greg

[Rich72C10]

My brother and I kicked ourselves in the butt over the fuel tank - we did a lot of things, like replacing the fuel pump, before figuring out it was a nasty tank. The sad part is we had a good sign the tank needed at least checking when we had to replace the sending unit because the float was 1/3 (if not more) rusted away causing the fuel gauge not to work.

Hind sight is sooo 20/20 on my thread from last year. After reading it over again we were also fighting a bad carb I got off eBay - which is one of the main reason when I finally got what I think is is good replacement I sent it off to Quadjet Power. Everything I have read is nothing beats a properly turned Qjet!

You very well may be dealing with a Carb that needs to be rebuilt but insuring your tank is in good shape, IMO, is a good thing to check out and to eliminate as an issue.

[Davidf]

Rebuild the carb. Good place for a kit is Quadrajetparts.com. Flooding can be caused by needle valve not seating or well plugs leaking. 1705xxxxx carbs usually don’t have the leaking well plug problem. Quadrajet are super simple and easy to rebuild. Choke/pull down are most fiddle bits. Probably should pull the idle tubes before cleaning. If you careful, you can get out originals and still be able to reuse.

Edit: Just noticed, you have a 1708 carb which is post 1976, so probably the well plugs are not the cause for flooding

[HO455]

As folks have said your float level is incorrect. One very common cause of that issue is for the float to have sunk.
On a brass float it can get a small hole in it allowing fuel inside. This is easy to determine by shaking the float. You can feel/hear liquid inside.
A composite float will absorb fuel overtime and become heavy, and won't float as high as they should causing flooding. You can compare the weight of a new float to yours to confirm it has become fuel soaked.
Both versions can have the float level reset to temporarily repair the issue, (and to help troubleshoot the issue) but a new float is recommended.

[twoskies]

Thanks for all the Help
might of fixed it, the new filter came with a shorter spring, swapped it with another one from another quadrajet and seems ok now


Again appreciate all the help

[Davidf]

Filter has nothing to do with flooding. If the carb inlet filter has the wrong spring, it could cause the filter to unseat and be ineffective.

[twoskies]

Took the truck for a spin to the local Menard's, runs good, but still seems like it was flooded on startup, had to push pedal to floor to start
same when i got back home, shut off and wouldnt start till i pushed pedal to floor

ill get it pulled sometime this week

Thank's