Changing a Mechanical Fuel Pump - '78 New Yorker

[rsbolin]

Alright, forum. I continue to have long crank issues with my '78 New Yorker. After a lot of work done by a carb shop here in Greenville, SC including fuel tank replacement, fuel sending unit replacement, carter quadra-jet rebuild, new spark plugs, and a few more items, she started easily and ran well. Now, she has a long crank, i.e. 15 to 20 seconds, like she is not getting fuel. So, I have a NOS fuel pump that I purchased from Mobile Parts in Upstate New York State (Craig is great source for NOS if you need anything).

What steps do I need to take to replace the fuel pump? I watched a video on YT that stated it is a easy enough job, but I want to gain some insight from the experience of this forum.

Happy Friday to all.

Ron

 

[Big_John]

That description of your problem doesn't really sound like a fuel pump problem to me. Before you change a fuel pump trying to solve a problem that might not be the pump, there's an easy way to check the pump.

Disconnect the fuel line and attach a hose running to a soda bottle, disconnect the coil wire and crank the engine and see if there's a good stream of fuel.

It should be a strong stream of fuel, filling the 16oz. soda bottle halfway in around 10 secs or less.

I could be wrong and it is the pump, but changing things without testing or really figuring out exactly what the issue is, could bring about more problems. Often, folks figure because it's "new", it's good. Sometimes that's not the case. While that may not be the case with your NOS pump, you need to adopt that mindset before you just start swapping parts. It can take you down the rabbit hole where suddenly you have more problems than you did when you started.

If you do end up changing the pump, you also need to pull the fuel pump pushrod and check the length. They tend to wear... A cheap digital caliper from Harbor Fright will do the job and the pushrod should be 3.22" in length. You remove the pushrod by backing out the allen head plug under the pump. Grease it up when you put it back and it will stay up out of the way when you put the pump on.

And just because I'm typing.... Longgg Island isn't "Upstate New York". It's like me calling South Carolina "North Carolina". You can't get further downstate (south) than Long Island. Sorry... I could get into a discussion about the definition of "upstate" as it means different things depending on where you live and who you talk to but I'm really just poking fun here.....

 

[rsbolin]

That description of your problem doesn't really sound like a fuel pump problem to me. Before you change a fuel pump trying to solve a problem that might not be the pump, there's an easy way to check the pump.

Disconnect the fuel line and attach a hose running to a soda bottle, disconnect the coil wire and crank the engine and see if there's a good stream of fuel.

It should be a strong stream of fuel, filling the 16oz. soda bottle halfway in around 10 secs or less.

I could be wrong and it is the pump, but changing things without testing or really figuring out exactly what the issue is, could bring about more problems. Often, folks figure because it's "new", it's good. Sometimes that's not the case. While that may not be the case with your NOS pump, you need to adopt that mindset before you just start swapping parts. It can take you down the rabbit hole where suddenly you have more problems than you did when you started.

If you do end up changing the pump, you also need to pull the fuel pump pushrod and check the length. They tend to wear... A cheap digital caliper from Harbor Fright will do the job and the pushrod should be 3.22" in length. You remove the pushrod by backing out the allen head plug under the pump. Grease it up when you put it back and it will stay up out of the way when you put the pump on.

And just because I'm typing.... Longgg Island isn't "Upstate New York". It's like me calling South Carolina "North Carolina". You can't get further downstate (south) than Long Island. Sorry... I could get into a discussion about the definition of "upstate" as it means different things depending on where you live and who you talk to but I'm really just poking fun here.....

Good information. I failed to list that the fuel line from tank to pump has been replaced in the last 200 miles, as well as the fuel pump and the fuel filter. Once started she idles wonderfully, but as soon as you give her even just the slightest pedal, she bogs down. I can get past that by giving her high rev, but again, she bogs and dies if try to casually give her the gas.

I will try the soda bottle test.

Poking back:
As for Upstate, I thought that is what I was told, but if incorrect, my apologies. Greenville, Greer, Spartanburg, Travelers Rest, Simpsonville, Mauldin, all makeup the "Upstate" of SC, so I catch your point about one versus anything else.

Ron

 

[Big_John]

Good information. I failed to list that the fuel line from tank to pump has been replaced in the last 200 miles, as well as the fuel pump and the fuel filter. Once started she idles wonderfully, but as soon as you give her even just the slightest pedal, she bogs down. I can get past that by giving her high rev, but again, she bogs and dies if try to casually give her the gas.

I will try the soda bottle test.

Poking back:
As for Upstate, I thought that is what I was told, but if incorrect, my apologies. Greenville, Greer, Spartanburg, Travelers Rest, Simpsonville, Mauldin, all makeup the "Upstate" of SC, so I catch your point about one versus anything else.

Ron

Hmmm.... With a little more info, that could point to a fuel delivery issue. If your test doesn't do well, I'd look at the push rod length.

Yea, "upstate" is defined pretty loosely by some folks in New York City as anything north of them. It get comical sometimes. The funny thing is that I've talked to people from other places, including Europe that have traveled the US and they tell me that the farther north you get in New York State, the more it becomes like parts of the south... Only with snow. LOL!

 

[CBODY67]

ONE other "little poke" . . . the Carter spreadbore carb is NOT a "quadrajet" (which is the tradename for the Rochester (GM) spreadbore carb). Carter ThermoQuad.

Additionally, any NOS fuel pump probably does not contain a diaphram made out of ethanol-resistant diaphram material. As 1992 was when normal fuel lines' rubber was upgraded, fuel pump diaphrams might have been, too? Just my suspicion. So it could well start leaking well before it would if a recent-production mechanical fuel pump might. So, be on the lookout for such, just to be sure and safe.

On the fuel pump pushrod, be sure to lube the ENDS so there is initial lube upon start-up.

Enjoy!
CBODY67

 

[bronze turbine]

I would not use a NOS fuel pump with ethanol gas. Also, what are your expectations for cranking? I've always had to crank these cars a lot when starting if they sit for a while, because the fuel evaporates from the carb. Ethanol fuel evaporates faster. Also, I've always had to pump the gas pedal like 3 or 4 times for best starting. This sounds like more of a carb problem than a fuel pump problem. Bogging down is definitely a carb problem. If there was a fuel delivery problem you would see the problem at higher speeds like driving on the interstate. I suppose if the fuel pump push rod is worn it might not be pumping enough fuel when cranking but does pump enough when the engine is running. Just some random thoughts.

And now just a little story. I once had a 1980 Mirada with a slant six. I always had to pump the gas 3 or 4 times before cranking it for it to start. One time when I took it in for some work I asked them to rebuild the carb. For about the first two weeks after the carb was rebuilt, I only had to set the choke and turn the key for the car to start--no pumping. But after two weeks it was right back to the needing 3 or 4 pumps of the pedal for starting.

 

[CBODY67]

In an OLD aftermarket service publication, somewhere, it mentioned that a fuel pump would be super-efficient at pumping fuel at low rpms, but output would start to taper off at higher rpms.

On this WHOLE situation of "extended crank time" when starting from a hot soak condition, or after sitting a few days. I've been pondering and watching other engines in similar situations. NONE seem to attract the complaints as Chrysler B/RB engines do. Yes, I've experienced it on our '66 Newport, my '70 Monaco 4bbl, our '72 Newport 2bbl, etc. But WHY?

All of the carbs which Chrysler has used have ample float bowl capacities, especially when compared to a Rochester QuadraJet, for example. Yet I heard no complaints from the Chevy 454 owners back in the 1970s-1980s. As if Chevy owners just put up with it and Chrysler owners do not? What we had issues with on the Chevy 454s was heat affecting the starter solenoid operation.

In my own case, I learned what the car liked, in that situation, and did NOT depress and then release the accel pedal through all of this, following the Chrysler recommendations of 1/3 throttle to start. After I learned how to finesse things, plus making sure the spark plugs were in good condition and gapped correctly, the problems were diminished. Back when we still had decent fuel.

But still, from an engineering orientation, why do Chryslers tend to have these issues and other brands (with just as much, if not more) cast iron under the hood tend to not have them?

MIGHT it be due to the ignition coil not getting enough voltage when starting? Even with a fully-charged battery? Or perhaps a "conventional wisdom" approach to spark plug (and gap design) rather than going to a NGK V-Power or fine-wire Iridium style of spark plug?

There has to be an answer somewhere. This situation existed decades before we got ethanol'd fuels, which seem to make things worse. Yet in my GM cars, no such issues nor have I read anything about them in GM-oriented forums, either.

Just some extended ponderings over the past 45 years,
CBODY67

 

[rsbolin]

ONE other "little poke" . . . the Carter spreadbore carb is NOT a "quadrajet" (which is the tradename for the Rochester (GM) spreadbore carb). Carter ThermoQuad.

Additionally, any NOS fuel pump probably does not contain a diaphram made out of ethanol-resistant diaphram material. As 1992 was when normal fuel lines' rubber was upgraded, fuel pump diaphrams might have been, too? Just my suspicion. So it could well start leaking well before it would if a recent-production mechanical fuel pump might. So, be on the lookout for such, just to be sure and safe.

On the fuel pump pushrod, be sure to lube the ENDS so there is initial lube upon start-up.

Enjoy!
CBODY67

Yes, absolutely. Carter thermoquad. I had a picture of it and knew it is a quadrajet. I have been watching video on bogging on Qudrajets and it must have stayed at the front of my memory. The guy I purchased the fuel pump from said it was ethanol compatible.

This carb has now been rebuilt twice since January. The owner that purchased from the estate had rebuilt in January. When I purchased from him with 17,715 miles on it, I decided to have it rebuilt again since I was replacing the tank, fuel lines, etc. At the same time I had the plugs, distributor, wires also replaced.

Right now I cannot get it out of my driveway with one foot on the brake and a lot of foot on the gas pedal.

 

[CBODY67]

The Carter ThermoQuad is not a difficult carb to rebuild, IF you know what you've got. Many people consider a "carb rebuild" to be a generic labor operation that anybody can perform, unfortunately. AND those things are not inexpensive, either. Obviously, if the original problem still exists, the "rebuild" did not fix it OR discover WHY it is there in the first place.

IF the "bogging down" happens just off-idle, as the throttls is opened, like it accelerates then falls flat on its face, so to speak, that CAN be because a prior rebuilder left out the power piston spring and the second rebuilder did not know it should have been there. An easy check, though.

With the engine stopped, remove the air cleaner and then look to the center of the carb air horn, just behind the choke plate, to the driver's side from the picec of linkage that attaches to the choke plate there. You will see a triangular-shaped piece of thin, flat metal, secured with 2 slotted-head screws. From the side of that plate, there should be a thin "arm" extending from each side of the barrel that plate covers. With the engine off, the arms (attached to the power piston) should be level with the top of the air horn, such that they can be depressed, both move together as one, and then spring back up to their "zero vacuum" position. IF they are sunk down, there is no spring under that power piston, which means the primary metering rods are in the "full economy" position and stay there all the time. No power enrichment with higher engine speeds or anything faster than hot base idle.

It will be your task to check this and report back, when you can, with what you found.

Withi the metering rods in the "full down" position, the car should still start and idle as normal, just that when you throttle into it from idle, it does not respond as it should. IF you take off from a red light, all acceleration stops as soon as the accel pump shot is used. IF you go to WOT and hold it there, the engine rpm will build slowly until the secondary air valve will open. At which time the rocket thrusters kick in with more fuel.

ONE other thing is the spark plug wiring. Reversing #5 and #7 plug wires, which fire consecutively, will cause a very doggy engine, until enough rpm is gained and the mechanical spark advance kicks in. So, check this, too.

Please advise what you find,
CBODY67

 

[darth_linux]

Hmmm.... With a little more info, that could point to a fuel delivery issue. If your test doesn't do well, I'd look at the push rod length.

Yea, "upstate" is defined pretty loosely by some folks in New York City as anything north of them. It get comical sometimes. The funny thing is that I've talked to people from other places, including Europe that have traveled the US and they tell me that the farther north you get in New York State, the more it becomes like parts of the south... Only with snow. LOL!

Just watch "South Main Auto"s youtube channel and you'll see that that is true . . .

 

[mobileparts]

Have no fear, for those of you have voiced fears...
The fuel pump Captain Ron received from me --- I S --- ethanol gas compatible material......
Craig,,,,,

 

[Boydsdodge]

Good information. I failed to list that the fuel line from tank to pump has been replaced in the last 200 miles, as well as the fuel pump and the fuel filter. Once started she idles wonderfully, but as soon as you give her even just the slightest pedal, she bogs down. I can get past that by giving her high rev, but again, she bogs and dies if try to casually give her the gas.

I will try the soda bottle test.

Poking back:
As for Upstate, I thought that is what I was told, but if incorrect, my apologies. Greenville, Greer, Spartanburg, Travelers Rest, Simpsonville, Mauldin, all makeup the "Upstate" of SC, so I catch your point about one versus anything else.

Ron

Take a picture of the carb from both sides and post it if you can. I have seen general repair shops zip tie/ wire open the secondary air door. I would also like to see what carburetor you have. I leaning to push rod and tune. Here is a diagram of the step/power piston set up.

 

[thethee]

Take a picture of the carb from both sides and post it if you can. I have seen general repair shops zip tie/ wire open the secondary air door. I would also like to see what carburetor you have. I leaning to push rod and tune. Here is a diagram of the step/power piston set up.

View attachment 600073

I'll admit a single car isn't a big testpool by any means but for that single car of mine the 1.5 turns mentioned in step 2 was way too lean. Based on that I'd suggest at least double that for ethanol gas.

 

[rags]

I have seen general repair shops zip tie/ wire open the secondary air door. I would also like to see what carburetor you have.

you have experience with thermoquads. ever see the main wells crack? maybe one of his is and it's leaking a bit causing the long crank time to clear out the leaked fuel. hope that whoever did that carburetor has plenty of experience with them. there is a lot to miss. @Dana comes to mind.

 

[Boydsdodge]

you have experience with thermoquads. ever see the main wells crack? maybe one of his is and it's leaking a bit causing the long crank time to clear out the leaked fuel. hope that whoever did that carburetor has plenty of experience with them. there is a lot to miss. @Dana comes to mind.

I have been rebuilding Thermoquads for quit a while. I love them, I have not had a cracked body but the glued on wells leak. I have repaired the wells with good fuel epoxy. I have seen where people forget the two screws under choke door and have tried forcing the top plate up warping top plate and cracking body.
Loose throttle shafts can be a killer.

 

[rags]

the glued on wells leak.

that's what i was referring to. crack at the seam. i was involved with thermoquads 30+ years ago. that's what i remember happening but wasn't sure. still have two milk crates full of parts in the loft of my garage. at some point i bolted two AFBs on to the '69 and never looked back.

 

[Big_John]

Personally, I love the Thermoquads. I've had a few and they were great.

It's been my observation that there are three kinds of them... One type has been rebuilt/maintained by someone familiar with the Thermoquad. They run great. The second type are ones that have been worked on by guys that should never touch a carb. Sometimes, if you take it away and give it to someone that knows what they are doing and have a good carb. The carb on my 70 (yes, it has a t-quad) was a good example of that. The third type is there are Thermoquads that are just duds for one reason or another.

Many years ago, when the carbs were still be offered on new cars, the grinding job shop behind where I worked (knew a couple guys there) had the contract to regrind the plastic bodies for Carter. Seems they had a bunch that were bad, probably from the supplier to Carter, and needed to be ground flat. That doesn't mean much in the big picture, but it shows there were issues, even when new.

All that said, we all need to remember the old adage about most carb problems are electrical in nature and not forget to start checking everything.

 

[CBODY67]

Personally, I love the Thermoquads. I've had a few and they were great.

. . . we all need to remember the old adage about most carb problems are electrical in nature and not forget to start checking everything.

^^^^^^^^

I like TQuads, too. Much better to work on that QuadraJets. ANY carb which requires partial disassembly just to get the top off of, is not designed "right", to me.

I put a 9801 TQ on an Edelbrock Torker 383 on my '67 Newport. The literature said it was calibrated and matched to a 383 and that intake manifold. Main issue I discovered as getting the secondary air valve adjusted correctly. Neat little tool for that! Even bought a Strip Kit, too! Had to put the OEM base gasket on it for it to run right.

Epoxy on the well seals is no different than on a QuadraJet, fwiw. But that tube going to the accel pump nozzle always looked a bit flaky to me.

Enjoy!
CBODY67

 

[rsbolin]

Take a picture of the carb from both sides and post it if you can. I have seen general repair shops zip tie/ wire open the secondary air door. I would also like to see what carburetor you have. I leaning to push rod and tune. Here is a diagram of the step/power piston set up.

View attachment 600073

Pictures of the carb is added. I notice that the secondary is open until I actually start the car and then it closes. It feels like there is no tension on the secondary. It dangles until the car starts.

 

[Boydsdodge]

Your secondary air door is too loose. Do you know how to adjust the door with out unwinding the spring?