Shade tree mechanic! Whatcha workin on.

[Magicman]

Accelerator pump.  It should give a squirt of gas when the pedal is quickly depressed.

[doc henderson]

Thanks Lynn.  That is what started this.  the truck sits more than not.  when working on the brakes, it developed a big leak at that diaphragm and why I replaced the accelerator pump.  it seems to work with a big squirt.  I did add a washer to take slop out of a shaft, so I may remove that.  it allows for a manual throttle knob vs a foot feed to be used.  I cannot see how that would affect it.  but it has to be something simple I did, because even with the bad accelerator pump, it idled and throttled up normally.  This Holley has a governor.  state model under President Carter (no longer the worst president we ever had IMHO).  so, it tops out at 60 mph.  

[doc henderson]

https://www.youtube.com/watch?v=mE4LsFgPw2c

[Magicman]

Pumping the accelerator before cranking was a habit that we all had to break as carburetors were phased out.  I had to think a bit before remembering that squirt during a quick acceleration instance.

[doc henderson]

I got the whole carb kit with what seems like a thousand O rings and gaskets.  It is a little more complex with a vacuum assisted secondary to the 4 barrels.  I have been told it could be a bad power valve, but it is getting plenty of fuel.  also, may have damages something like the big diaphragm to the secondary barrels.  I do not know enough to test what is working and not.  I may try replacing some of these things, but it worked fine but for the leak.  It is possible that other rubber components are rotted but did not fail till I stressed it.  It did something weird one time when i put it on and was going full throttle and had to pull the linkage back.  After that it went back to the prev. behavior of when I hit the gas, it almost dies.  It is also harder to find old guys that understand these carbs.  Hard to tell who really knows about them.  The guy who claims to know all about them, may know far less than the guy who claims to know a little.  Kind of like the veteran who tells all kinds of detailed stories vs the one who says little.  The latter may have seen the most horrific crap.

[doc henderson]

I have the stuff to rebuild the whole carb.  I would be more interested if it worked ok, as it may be something dumb I did, and prob. simple.  The more I "fix", the more things are possible that I did wrong.  It comes with good instructions.  Not the time to adjust the timing as an example.  

[Jack S]

Doc.  I had a similar problem on an old ford like yours around 30 plus years ago. it turned out to be a intake manifold leak. when hitting the accelerator try pulling on the choke and it will help firing up if in fact you do have an intake leak. In fact it could be a vacumn leak at some other source as well. Sorry I didnt take the time to go back and see if this had already been mentioned. Those big ol vintage ford v8s were notorious for the issue you have    Hope this might help     Jack  

[beenthere]

Not sure why, but the problem sticks in my mind that it was "vacuum advance" related. Hope you track it down, whatever it is. 

[TimW]

Doc, for a vacuum leak, spray carb cleaner (while idling) all around the carb and any suspected area, like hoses and blocked off ports.  If the engine revs up, that is where your leak is.  Intake manifold leaks are vacuum leaks.

Bad thing about carb rebuild kits is they usually have left over parts.  So you really don't know if you used all you suppose to use.  After taking the carb apart, soak it in an ultrasonic cleaner.  Wore out butterfly shaft(s) might be the culprit too.

[doc henderson]

I tried the spray test.  no change in rpms.  new gasket under carb.  floats are set to factory spec.  It may be a linkage thing, but the butterfly's open on the primary half.

[Wlmedley]

Pic of my input shaft.Machine sat for years before I got it and thinking clutch splines may have rusted.Machine is hydrostatic drive and clutch is only used to engage PTO.Sorry Doc I can't give any input on your problem. I've forgot most things I knew about carburetors.

[doc henderson]

looks mostly worn where the clutch plate splines engaged.  I would think once turning, the splines would take up the slack and run fine.  

[TimW]

Years ago I had a Holley 1850 (?) and rebuilt it.  It still didn't run right.  I took it to a carb shop and was told the butterfly shaft was worn.  The butterfly worked, but the wear allowed internal leakage, as I remember.  He told me to replace the carb.

But your might want to do an online search on fuel injector kits to replace the carb for you engine.

Or just replace the carb.

But first I would search for a local speed shop to inquire about a qualified carb guy who can help you.

Or even ask the local heavy truck repair shops.

[doc henderson]

when I mention the governor all the guys so far take a step back.  That is why I do not just replace it as there are functions that I am not sure how to bypass so they do not mess with it.  It is a 361 honey of a oney and has a 4-speed ford Alison automatic transmission.

[Jack S]

Again Doc  apply some choke as you  accelerate if it helps then go for vacumn leaks. No it doesnt fix the problem it helps source it. I see you changed the vac boost how about the hose that connects it to the manifold. Start eliminating any vac lines off the manifold. 
as you said where are the old guys well I am one and have been there big time in my younger days A very common problem back then. 

[doc henderson]

vacuum running 17 to 20.  great info.

[barbender]

 I have an '02 GMC Duramax that has a fuel restriction or air leak. The LB7 first gen Dmax are notorious for this as they have neither mechanical or electric lift pump and the injection pump has to pull fuel all the way from the tank. 

 There's several companies with products to solve your problems. FASS being one, with a lift pump/filter kit that runs about $450. To me, this is something you install with oversize tires, lights, and a tuner- I don't need or want any of that. So I am I'm the middle of swapping in the same $25 Amazon 12v fuel pump that I replaced the mechanical pump with on my diesel sawmill engine. If it doesn't work out, I'll spring for a more expensive pump. But I suspect it will do fine 

 I can have lots of spares and I mounted it where I can swap one in 20 minutes😁

[rusticretreater]

@Wlmedley Sorry to say but that shaft looks like it is toast.  It would only be a short while until the clutch disc would be wobbling badly if not stripped out.  There is a tremendous amount of force going through the hookup when engaging and proper mating surfaces are needed to bear the strain.

[Wlmedley]

I'd say your right and probably wishful thinking on my part.I tore the thing down outside because it gets pretty hot in the garage and I can see better. I bought a aftermarket clutch disc although I haven't received it yet so I'm thinking when I get it I will probably put it back together and try to make it until mowing season is over and tear it back down this winter inside and fix it properly.I'll only be out a $70 clutch disc and shaft will be replaced anyway.Kubota is sure proud of their parts.

[barbender]

 The Duramax- Amazon fuel pump was a success, got it all hooked up. Not scientifically verified, but it flows half a 32 Oz Gatorade bottle in about 10 seconds up at the fitting right off the filter head. 

 Truck runs great and has power again👍👍

[rusticretreater]

@doc henderson I have experience in Holly carbs.  My 1970 Chevelle has one on it now.

So we are talking a 600cfm Holly 4bbl carb, manual choke, vacuum secondaries on a Ford 361 engine?

The accelerator pump attaches at the drivers side rear of the carb on the underside.  When you replaced the pump diaphragm, did you turn the carburetor over?  The way to do it is to put a large punch in a vise, sit the carb on the vise with the punch through a bolt hole and swap it out from underneath.  When the carb is turned over, accumulated dirt in the bowls goes everywhere and easily clogs up passages in the metering blocks.

If you did this, I would recommend a full rebuild.  It is not hard but takes thoroughness, cleanliness and a clear work area.  You also need a bath to soak the carb in.  The carb cleaner needs time to seep into the passages and work on the dirt.  You agitate it a few times during the soak to try and get air out of the passages.  The key is to use compressed air to blow out all the passages(both directions if possible).  I remember one time hearing the clog come out of a passage.  You can also use a can of carb cleaner with the red tube to blow the cleaner into the passages.  As noted, an ultrasonic cleaner would be useful, but you still want to blow out the passages.

Also, when I blew out a power valve on my holley, it simply just dumped gas into the intake.  My idle was all over the place and it sounded like I was revving the engine a bit. So I doubt that is your issue.

The governor can be removed from the carbs but you probably want to leave it.  Driving a behemoth like that loaded at speed might overwhelm the brakes.

Many folks typically go for a new carb at this point as the new ones are far superior to the old ones and its an easy way out of the dilemma. Unfortunately, the price tag is $400+.  Folks also use an Edelbrock AFB carb.

[doc henderson]

I was hoping it was simple.  I do have an ultrasound machine and have the dip carb cleaner.  I can do all that.  My dad, uncles and brothers have done all this.  I do not remember the cfm, and the 400 bucks would have been worth it by now, but I do not know the unintended consequences of transplanting another carb onto this.  the accelerator pump is on the bottom drivers-side front of the carb.  the vacuum secondary is on the right, and the throttle and accel pump assembly mechanism is on the drivers-side.  good info.  I will update when it is working normal again.  thanks all.

[TimW]

Did you mean Ultra sonic cleaner, instead of ultrasound machine?  I couldn't get a log splitter carb cleaned out completely, until I put it in the shop's ultra sonic cleaner.

[doc henderson]

Yes, I did!  thanks Tim.  I am taking Benadryl and med for a cold.  musta conflated my day job and my hobby projects.        

[barbender]

 I was wondering just how involved Doc's shade tree mechanic tasks were getting! Lol