The car is a '54 Nash Rambler, the carb is a Carter YF with tag number 2014S. If I squirt a little gas down the carb throat the car will start up and run very well. But it will not start unless I prime it, and pumping the gas pedal does not squirt any fuel in to start it. It has no accelerator pump "shot". There's tons of nice videos online about Carter YF's including several showing accelerator pump testing but none of them look like my carb inside. On every other Carter YF there is a check ball or check needle in the spot where I'm pointing my toothpick in the photo below. Then inside the carb throat there would be a nifty little tube that shoots out a little stream of fuel when you pump it. Note that my carb does not have that. It's blank there, and there is no little tube for the accelerator pump. It's not filled in or modified to be that way, the p***age that would have been cast in is not there either. My carb has both check balls built into the accelerator pump housing, one on each end. I did confirm that both were clear and moved freely. I also checked the discharge ball side by holding it down and pumping the pump rod, it would hold pressure, and shoot out when you let go, so that seems to be working correctly. Here's where **** gets dumb. Apparently, the accelerator pump shot is supposed to come out of the nozzle at the top, as poined out by the toothpick here. This is confirmed by the factory manual I have on it. The problem is, it doesn't work, so you can pump the **** out of it and never get any fuel out of that nozzle. If I push the accelerator pump down with my finger, while the top is off, I can get a little fuel up there, but I have to squeeze it down quite a ways and let off to move any fuel (its supposed to pump on the return stroke), but when everything is together, the linkage only ever moves the pump rod like 1/8", and I have to go way beyond that to get any fuel up to the top. First pic shows the rod where it usually sits. Second shows it depressed as far as it'll go with the linkage. Not much. I also noticed when I pump the accelerator pump, fuel seems to build a little pressure in the pump and then just percolate up back through the metering jet. (I made a video of this but I can't embed it because it's too short, here's a link that hopefully works https://youtube.com/shorts/aA4W83pHlWw?feature=share ). Apparently all of the jet p***ages to the nozzle are all connected, so it makes sense that fuel would back flush there, but then, how did this ever work? If I plug the metering jet hole and pump it, I can get fuel out. I don't understand carbs very well anyway, and this one is really twisting my brain. I can't drive the car anywhere if I have to prime the carb under the hood every time I start it, but I can't seem to make this one squirt fuel, and I don't even really understand how it ever worked. Questions. 1. Is there something wrong with this carb? 2. Is the carb fine and there's some novel way of starting it without the little accelerator pump shot out of a separate circuit that every other carb has? 3. Can I just swap this carb out for a different YF that has the little built-in accelerator pump squirter circuit in it and smash this one to bits with a hammer while laughing maniacally? Seriously, God bless you if you read this far and have any kind of guidance to give me. I've had this car for 2 years (see the build thread here if you want https://jalopyjournal.com/forum/threads/1954-nash-rambler-light-re-commissioning.1337941/ ) and I did so much work on it last year and I have never driven it out of my own parking lot for just this reason. I need to figure this out.
A couple other pics from my factory manual (which I only have thanks to In_The_Pink) which show that the p***age for the accelerator pump shot, the metering jet and the low speed jet are all interconnected, so putting a bit of fuel pressure in there just pushes the fuel back out of those two holes on the way to the nozzle. I can't figure out how this ever worked.
Silly question, have you blasted that circuit with air in both directions just in case there's some **** stuck in there. Might also be a good idea to soak it in carb cleaner beforehand ..... I apologise if you already mentioned doing that. Just thought of other possible hinderances, is the spring loaded check ball free to move when it's ***embled. They can sometimes jam if the spring is previously changed out for some reason and/or if the ball has worn a ridge into the seat/casting and is then getting stuck.
Not on your carb, but a Rochester 2 GC, for Tri-power, I had one that didn't have the p***age drilled out going from the accelerator pump well. I had to drill it and then plug the outside edge with epoxy.
It is a weird pump circuit: Part of your starting problem might be the volatility of modern fuel (the fuel may have evaporated out of the bowl). If the bowl is full, and the automatic choke is correctly adjusted, the engine should start without pumping when the ambient is above 20 degrees F. An electric fuel pump, to prime the carburetor bowl, might be in your future. On the other hand (there are 4 fingers and a thumb): The aftermarket YF carbs for Chevrolet, have exactly the same size internal main, primary, and secondary venturii; but with different fuel calibrations. These carbs have the conventional accelerator pump circuit. Applicable part numbers for the Chevrolet YF's are: 964s with manual choke, or 965s with automatic choke. Jon
First off, thank you all for the replies. You guys are the best. This kind of **** is what drives a man crazy. Not silly at all, since I didn't mention, but yes, I did blast those p***ages with air and I confirmed the air is coming out the other end, it's very clean inside. I also did confirm that both check balls in the accelerator pump housing are working as intended. Honestly, just hearing you tell me "it is a weird pump circuit" makes me feel a lot better, I was baffled trying to figure out how it ever worked. The first thing I'm going to do is reset the choke and see if I can get it to work that way. I know for a fact that I have it dialed back so it's more open, my other cars will start without the choke on a warm day just fine but that does make sense. I will report back on this. Fuel pressure wise, I rebuilt my fuel pump and it makes tons of pressure, so much that I had to put a regulator on it to dial it down, when I removed the carb to look inside yesterday the bowl was full so I don't think that's an issue. @carbking my followup question would be, if I can't make this work with just the choke and I did track down one of those other YF's, could I use my original base on the other body (to retain the correct linkage and also because my throttle shafts are really nice/not worn) and/or also my top plate (to hold my stock air cleaner and retain the original choke)? And if I did that, would I reuse my old metering jet, metering rod, and low speed jet, or would I need to use the pieces from that other carb? Because in a couple weeks Wisconsin is having our biggest/best swap meet of the year and the idea of tracking down one of those Chevy carb bodies and building a hybrid carb where it has that separate accelerator pump circuit but with everything else the same sounds very appealing. I really appreciate your feedback here.
Is there any chance that some of these carburetors could have been built from the factory without an accelerator pump? I vaguely recall that some carbs were built that way.
In the first shot of the shop manual you posted is a description of how the pump circuit works. The way I read it, the accelerator pump is not activated strictly by moving the throttle linkage. It also involves spring pressure being applied to the pump diaphragm when it can overcome the manifold vacuum under the diaphragm keeping the spring compressed. It sounds a bit like the way a power valve works. It applies a pump shot more by engine load (low vacuum) than strictly by mashing the gas pedal. I've never run into a system like this before, but maybe it was a part of the reason why Rambler made claims to have such good fuel mileage. Don't know if any of this applies to your cold start problems. But changing to a different model of this carb may improve cold starting, though possibly at the loss of a tiny bit of fuel economy.
[QUOTE="Squablow, post: 15923422, member: 5943 @carbking my followup question would be, if I can't make this work with just the choke and I did track down one of those other YF's, could I use my original base on the other body (to retain the correct linkage and also because my throttle shafts are really nice/not worn) and/or also my top plate (to hold my stock air cleaner and retain the original choke)? And if I did that, would I reuse my old metering jet, metering rod, and low speed jet, or would I need to use the pieces from that other carb? [/QUOTE] I would not change either the throttle body or the airhorn, PERIOD ! I would first see how compatible the linkage would be; if not compatible, then possibly modify car linkage OR possibly interchange throttle shafts to retain the proper linkage compatibility. If you change carbs; build the replacement carb bone-stock, then tune from there. When migrating a carburetor from one application to another, it is really a good idea to build it to its stock configuration. Then you have a repeatable baseline. If you guess, and guess wrong, then you may guess wrong again. Jon
I checked my pile......sorry nothing that old (all early to mid 60s). Cheapish one the bay. https://www.ebay.com/itm/205861893875?chn=ps&google_free_listing_action=view_item
UPDATE I got the car back together and reset the choke to factory spec (1 notch "lean" on the Climatic Control little dial piece on the side) which I was a little surprised to find the choke plate basically all the way closed at 80 degrees F, but knowing what I know now about the weird accelerator pump circuit I guess that makes sense. I did successfully get the car to start with this carb without priming it, it took a LOT of cranking to do it, but some of that was expected since the float bowl and fuel filter were both empty because I had the carb off. I ran it around the block here (first time on the road ever, further than it's ever been, long enough for it to warm up properly) and I was able to restart it as well, the hot restart didn't take nearly as many cranks. Further investigation will be to see how many cranks it takes to start from cold but with the float bowl and fuel filter both full instead of dry (hopefully way less, I don't think it would have started this time without a fully charged 100% 6V battery, but again, it was basically dry) and I'm also curious to see how long it needs to cool off before that automatic choke will close itself off again. I will update more on those two things, but this has been a great day. Thank you to everyone who responded, especially Carbking but everyone else as well. The car does have some spark knock at partial throttle that I'll need to figure out but it starts and once it's running it idles beautifully so I'm making great progress.
I should add in quick, I did mention about the spark knock at part throttle, I have not checked the timing yet and I would not doubt someone has already futzed with that so I am going to check it, and also dwell angle since that can affect timing and no one ever seems to set that right. But is there anything carb related that would make it spark knock at part throttle? I don't think it has a vacuum leak (the intake is integrated into the head) but if anyone has thoughts here I'd love to hear them. I'm primarily a sheetmetal/auto body guy and not a very experienced mechanic so this is all a learning experience for me.
I would set the dwell and then set the timing and see if the detonation goes away I’m betting it will. Do you have a vacuum gauge? Also check vacuum at idle. Dan
Dwell/timing was my first thought, as someone had been messing around with this car trying to get it started in the past and I don't trust anything they did. But the vacuum gauge thing is a good idea, I hadn't thought of that and I think I have a vac gauge somewhere to throw on it, would be another good data point. In other news, I let the car sit for a few hours until it was cool, the choke was still wide open, but I just touched the plate a bit and it closed off, so I think the automatic choke might be a little sticky. Once I did that, I tried starting and I got it to start with a reasonable amount of cranks so I think it's mostly functioning as intended. Still a bit more cranking than I'm used to (my '57 is really dialed in and it'll start without even a full revolution) but I think that's just what this car takes, it does work, so that's great. Proper timing/dwell and maybe setting the idle mixture screw with a tach might help the starting a bit as well.
If @carbking checks back in here . . . Am I even close in my thinking about how this "weird pump circuit" works? This was as good of a guess as I could make after reading the description in the shop manual. https://www.jalopyjournal.com/forum...-desperate-for-answers.1352847/#post-15923494 Someone also asked if any carbs were built without an accelerator pump. I ran into one years ago that accidently left the factory without one. A friend had a Chevy Monza with a 2.5 liter and a Vara-Jet carb. It seemed to start OK and went down the road as well as could be expected. But it would barely pull itself thru an intersection from a dead stop. On closer inspection there wasn't any accelerator pump shot when opening the throttle. It had a pump plunger and spring and the necessary check balls, but no fuel ever made it to the discharge nozzle. I removed the air horn and the discharge port was drilled into the float bowl and air horn. And with the air horn removed, if you pushed the plunger it would shoot a stream of fuel straight up out of the bowl. The discharge nozzle wasn't visible when looking down into the venturi but in its place in the air horn was a port cross-drilled into the I.D. of the venturi. I had to get a lighted magnifier to get a look down into the port where I found a tiny br*** cup plug pressed into place, but there was no hole drilled in it. No hole, no pump shot. So to try to prove my su****ions I decided to put a hole in it. The only problem there was that the smallest bit I had was probably 5 times bigger than the hole needed to be. But I figured that too much pump shot was better than none at all. Of course this made the Monza come to life and it drove almost like a real car. My friend drove it that way for a few days until I could find a different used air horn (with a proper sized hole in the cup plug) at work from a similar Vara-Jet core. Swapped out the air horn which leaned out the pump shot quite a bit. And my buddy never came back around with any drivability complaints.
Clay - I have not had one of these apart, but from reading and looking at the prints, I would say you are close. LOTS of industrial carbs were built without accelerator pumps. Also, if you consider imports, think about the S.U., a**** others. And for the record, when I first started building Carter W-1's (one of the very best single barrel carbs ever made), I was amazed at how many had the accelerator pump disconnected. Lots of Chevy farm trucks in rural Missouri. During WWII, lots of farmers disconnected the accelerator pump to save fuel (fuel rationing). Jon
The way I read it is it’s not an accelerator pump in the sense we’re used to. It’s an enrichment circuit. It relies on both the movement of the pump lifter and manifold vacuum at the diaphragm to enrich the circuit. Fuel will only come out of the nozzle with the engine turning over as it relies on the differential pressure within the carb p***ages as it’s part of the normal fuel metering circuit. That’s why you can see it coming out of the jet in the float chamber In some ways it’s working like an SU carb to enrich the mixture as you open the throttle. They also have no pump.
The way I'm seeing it in the illustration, the plunger spring is what moves the diaphragm. But only when manifold vacuum drops low enough to allow the diaphragm to be moved. Does that sound right at all? It does look a bit like a Rube Goldberg contraption.
I think they both move it as the book says with the engine not running the pump will only expel half it’s normal volume.
Here's another bizzaro accelerator pump on a Rochester AA 2bbl. Pump is actuated by a rack and pinion arrangement. https://www.carburetor-parts.com/rochester-aa-accelerator-pump.html This stuff is starting to make my brain hurt.
Ouch ! I was having a pretty good week until you just had to bring up this thing ! While I really like most Rochester carbs, this is just one of their innovations that should have been left un-innovated ! Fortunately, this model lasted 2 years only ! Clay - I think you have too much time on your hands! Maybe you should take up stamp collecting ! If you are looking for unusual accelerator pumps, take a look at the "syringe accelerator pump" used by Stromberg on their type "D" carburetors. Jon
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