Accelerator Pump Replacement (Q-jet)

[ajkolar]

Is the replacment of the accelerator pump straight forward on a 4 bbl rochester quadrajet? Could anyone give me a quick description of what it takes or direct me to the appropriate documentation? Thanks!

 

[HT32BSX115]

Re: Accelerator Pump Replacement (Q-jet)

I'm assuming that this is a marine carb on a Mercruiser?

You need to get a carb rebuild kit. It will have instruction for rebuilding it in the box. Napa Autoparts sells Sierra Marine carb rebuild kits as do others.

Your other choice might be to buy a rebuilt carb from Flying Fish.

http://www.marinecarburetor.com/index.html


Cheers,


Rick

Is the replacment of the accelerator pump straight forward on a 4 bbl rochester quadrajet? Could anyone give me a quick description of what it takes or direct me to the appropriate documentation? Thanks!

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

I have the rebuild kit and really at this point just interested in replacing the accelerator pump. I haven't had time to look really close at the directions, just wandering if accelerator pump swap was pretty straight forward and what was involved?

 

[HT32BSX115]

Re: Accelerator Pump Replacement (Q-jet)

Well you can either follow someones (off the cuff) directions here or read them on your own.

I would trust the directions that came with the carb.

 

[Coors]

Re: Accelerator Pump Replacement (Q-jet)

Why not rebuild it while you have it apart.
If it failed, might be some more problems lurking in there.

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

To be honest, I'm just not comfortable rebuilding the whole carb. I am pretty handy and pick things up quick, but carbs are something I just have little to no expierence with and as Q-jets sound to be a little finicky / complicated, and with quality of the rebuild directs not being up to par (at least in my eyes) more than I want to tackle. Symptoms point to the accelerator pump as indicated by many other posts on this site and I would like to just swap it out to see if that remedies the problem. If not, I am thinking about just upgrading to a simpler Edlebrock 1409. Is there much more to swapping the acc. pump than taking off the top bowl cover assembly, and swapping the old one out for the new one?

 

[Coors]

Re: Accelerator Pump Replacement (Q-jet)

You'll probably have to buy the whole kit to get it (and instructions, more are on the net).

 

[Maclin]

Re: Accelerator Pump Replacement (Q-jet)

Maybe the passages are just gunked up, putting in a new plunger won't help that much. If you are really thinking about buying a new carb anyway why not take the chance on rebuilding this one yourself to gain experience. Then if you muck it up you have the perfect reason/excuse to get a new carb...but there is always the chance that you save the QJ (and some chump change) during the rebuild process and go on to enjoying the boat with no carb refit worries.

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

Well as long as I have the whole kit I decided to attempt a rebuild. I took the whole thing apart tonight trying to keep good notes and photos so it will go back together (using all pieces ;-) As far as cleaning goes it just says to soak non plastic parts in carb cleaner or lacquer thinner.... Anything I should pay particular attention to. Any other helpful advice. I.E. Should I use a tooth brush to scrub the small areas, etc....? Any advice on common mistakes when re-assembling the unit?

To be honest, as took things apart it really didn't appear to be to dirty or gummed up.... Or is the buildup rarely visible as it is in small passages, etc...?

Thanks for the help and encouragement!

 

[JustJason]

Re: Accelerator Pump Replacement (Q-jet)

Mail it to me and i'll do it for 100 bucks + the carb kit + return shipping...
I can probably knock it out over the weekend.

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

Thanks CaptJason, but at this point if things don't go well with the re-assembly I think I would rather stick my $100 into a new edlebrock now that I found out my cast iron intake will accept it with no adapter.

Any friendly advice is still appreciated!

 

[Coors]

Re: Accelerator Pump Replacement (Q-jet)

Gunk carb cleaner, overnite soak, blow out passages.
No plastic in the Gunk.

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

Gunk is a brand of carb cleaner I assume? Can that be bought in large volumes? What is the best container to use to soak the carb parts in? I would assume I need to stay away from plastics of any kind????? Thanks!

 

[rodbolt]

Re: Accelerator Pump Replacement (Q-jet)

after cleaning flip the body assy upside down and carefully epoxy the main well plugs, they tend to leak causing a hard restart after sitting for a few days and can cause a rich idle.
common mistakes are failing to remove the accelerator check ball,forgetting to reinstall it.
biggest two mistakes are bending the power valve/primary metering rods and forcing the cover on without making sure the secondary rods are aligned with the jets causing the jets to be shoved into the mainwell plugs.
other than that its an incredibly simple carb with no real issues and is probably the longest running vacum secondary 4bbl carb in production.
its been around since about 1965.

 

[JustJason]

Re: Accelerator Pump Replacement (Q-jet)

rodbolts correct. upon reassambly the bowl cover should go on nice and easy, if it doesn't fall into place then something is not aligned.

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

Rodbolt, Could you advise me a little more precisely as to what I should epoxy to prevent leakage. I have the carb completly dissasembled and am looking at the Bowl Assembly and the Throttle body assebly and not sure exactly what you were describing. I have attached two pictures below hoping you can identify what needs to be epoxied in the pictures:

 

[jonsquatch]

Re: Accelerator Pump Replacement (Q-jet)

I haven't seen one with a problem (although I have only ever looked at a handfull) but I believe these are the areas of interest. It is typically supposed to be the tops of the castings. I have seen them goobered over with epoxy.

 

[ajkolar]

Re: Accelerator Pump Replacement (Q-jet)

Well, the carb has been REBUILT! Directions made it look scarier than it really was. It is all back together and ran good in the driveway. Now I just need to find time to get to the lake and give it a test run. Wish me luck (and some free time)! Thanks again to everyone for their advice, help, and encouragement!