# Reliable stock fuel pump



## Duff (Jan 12, 2020)

I haven't checked it yet, but I suspect my auto parts store, mechanical ,fuel pump is putting out too much pressure. What brand of stock pump are you using on your Pontiac?


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## Scott06 (May 6, 2020)

I bought one from Ames and ended up with same issue too much pressure. Maybe not the solution you want but put a fuel pressure regulator on it and it fixed the issue


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## Duff (Jan 12, 2020)

I was hoping to avoid a regulator, but with the lack of quality in replacement parts, it looks like my next step.


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## RMTZ67 (Mar 12, 2011)

Duff said:


> I was hoping to avoid a regulator, but with the lack of quality in replacement parts, it looks like my next step.


Carter fuel pumps. Doubtful they have to much pressure....might be a carb/float issue


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## armyadarkness (Dec 7, 2020)

Myself and a few of the other people here (I think Bear and Lemans Guy?), run the Edelbrock. It's clockable and put's out exactly 6psi (depending on the model you get). Plus it's just a rebuildable, pro pump, which has greater volume capacity and it rebuildable.


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## Scott06 (May 6, 2020)

Duff said:


> I was hoping to avoid a regulator, but with the lack of quality in replacement parts, it looks like my next step.


Certainly make sure any potential needle seat or float issues are resolved first. 

If you have a rebuildable pump these guys have been mentioned in the past as getting them set up for a stock pressure. Then and Now Automotive

The Ames one I put on was doing 6-7 psi which would flood my Tripower set up and cause AFR wandering at idle. I have it set 3.4-4 psi and works great now. 

If you do go with a regulator be careful with gauge selection - i used a inexpensive Summit gauge on a Holley 12-804 ( 4 psi regulator), the liquid filled summit gauge gives variable pressure indication depending on gauge temp... so I put it on adjusted it to 4 came back was reading low... adjusted it up ... and had the same flooding issues - tried different needle and seats... and realized with that liquid fill gauge I had to set it when cold then ignore it. 

Once I did that the set up works great and I get good AFR across the rpm and throttle position range.


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## Duff (Jan 12, 2020)

When I bought the car it had a Holley carb that was running rich, just like the factory Q jet is now, I just had the Q jet rebuilt by a pro shop, so going to check the pump pressure before I look at the carb. I'll test the Carter pump soon and post results. The car had a cheap liquid filled gauge that showed erratic psi readings, if I need a gauge and regulator, I'll buy an Aeromtotive brand, I had good luck in the past with them.


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## PontiacJim (Dec 29, 2012)

Duff said:


> When I bought the car it had a Holley carb that was running rich, just like the factory Q jet is now, I just had the Q jet rebuilt by a pro shop, so going to check the pump pressure before I look at the carb. I'll test the Carter pump soon and post results. The car had a cheap liquid filled gauge that showed erratic psi readings, if I need a gauge and regulator, I'll buy an Aeromtotive brand, I had good luck in the past with them.


As has been mentioned here before, maybe you read it? The liquid filled gauges can fluctuate due to the internal pressures within the gauge itself. I recall someone saying they drilled a relief hole in the housing and that cured the fluctuations.


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## armyadarkness (Dec 7, 2020)

PontiacJim said:


> As has been mentioned here before, maybe you read it? The liquid filled gauges can fluctuate due to the internal pressures within the gauge itself. I recall someone saying they drilled a relief hole in the housing and that cured the fluctuations.


This is why I always recoment the Marshall guage to everyone. Theyve been in the game forever, are cheap, American made, have tech support, and a relief valve built in.


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## armyadarkness (Dec 7, 2020)

Amazon.com: Marshall Instruments LS00100 Silver Dial Fuel Pressure Gauge : Automotive


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## Duff (Jan 12, 2020)

Thanks, I'll check out the Edel pump and Marshall gauge, here's some info from Aeromotive. 
*uid-Filled Gauges vs. Dry Gauges, The Problem and the Solution – TB #903*

Click here to download the pdf.

Finding a fuel pressure gauge that is accurate, reliable, and affordable proves to be a surprisingly difficult job – more so than most enthusiasts realize. There are two main types of gauges on the market: liquid-filled gauges and dry gauges. A liquid-filled gauge is tougher and more durable than a dry gauge. If a dry gauge is under extended shock and vibration, its internals can get damaged and the needle falls off. The oil in a liquid-filled gauge protects its precision internals from shock and vibration, solving this issue. And there’s no arguing that a liquid-filled gauge looks like a higher quality instrument.

Unfortunately, there’s a hidden “gotcha” that users of this type of gauge experience: a reported lack of accuracy and consistency is common. In fact liquid-filled fuel pressure gauges do exhibit seemingly random pressure swings. The reason this happens is because, as the temperature under the hood heats up, the oil in the gauge heats and expands, causing the needle to move without any kind of pressure change within the system. Dry gauges, on the other hand, do not have these pressure swings that liquid-filled gauges do.

Here at Aeromotive, we are focused on eliminating fuel system compromises wherever possible, including gauge inconsistency. Our new liquid-filled gauges feature a special sealing plug that is fitted with a stainless steel pin-valve that can be pulled up slightly to equalize internal pressure and then pressed back down to re-seal. The gauge remains sealed but able to be equalized at any time, regardless of gauge temperature, immediately restoring accuracy and eliminating heat-related inconsistency.

Note: in order to use the pin-valve effectively, these new gauges require mounting so the face of the gauge is perpendicular (at a right angle to) the ground, and with the pin-valve/plug assembly on top.

Designed to the smaller, 2″ diameter size most popular with enthusiasts across the motorsports spectrum, these exciting new gauges feature a stainless steel case, polished bezel, heavy-duty brass 1/8″ NPT male connector, and are compatible with 1/8″ NPT female pressure ports found in most performance fuel pressure regulators. The white face with black numbers and hash marks is easy to read and includes the Aeromotive name and logo. Two versions are currently offered; 0-15 PSI P/N 15632 and 0-100 PSI P/N 15633, and are available now through any Aeromotive dealer or at: www.aeromotiveinc.com.


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## armyadarkness (Dec 7, 2020)

Duff said:


> Thanks, I'll check out the Edel pump and Marshall gauge, here's some info from Aeromotive.
> *uid-Filled Gauges vs. Dry Gauges, The Problem and the Solution – TB #903*
> 
> Click here to download the pdf.
> ...


That is the design of the Marshall Guage that I posted. They have always had a relief valve.


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## AV68 (Aug 18, 2021)

Just a kinda for whats its worth, if you install a regulator with a mechanical pump use the dead head style or else the fuel pressure will constantly hunt not hold steady, I'm dealing with the hunting pressure right now using a return type regulator with a Edelbrock mechanical pump, I like the function of the return type regulator just to keep fuel constantly moving for cooler fuel temps. I cant remember where i read it but traditionally 6-7 psi for carbureted is what you wanted but modern fuels needed 3-4 psi to work better with carbs, so most fuel pumps will need a regulator of some kind


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## RMTZ67 (Mar 12, 2011)

AV68 said:


> Just a kinda for whats its worth, if you install a regulator with a mechanical pump use the dead head style or else the fuel pressure will constantly hunt not hold steady, I'm dealing with the hunting pressure right now using a return type regulator with a Edelbrock mechanical pump, I like the function of the return type regulator just to keep fuel constantly moving for cooler fuel temps. I cant remember where i read it but traditionally 6-7 psi for carbureted is what you wanted but modern fuels needed 3-4 psi to work better with carbs, so most fuel pumps will need a regulator of some kind


Wow never knew that. I must be shoving fuel down the throat of my Z28 and Gto. What is the reasoning behind that? Kinda like a vaccine for our carbs?


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## AV68 (Aug 18, 2021)

I think the needle and seats cant hold back the fuel at that 6-7 psi pressure, maybe the new fuels additives make the fuel thinner or something ??
I was only having trouble at idle and warm to hot restarts with it being really loaded up when i restarted it, the added pressure regulator fixed those problems


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## RMTZ67 (Mar 12, 2011)

I have stock carter fuel pumps on both cars w/o issues hmm. Yours good at wot?


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## AV68 (Aug 18, 2021)

No problems at WOT, it was just at idle and hot/warm restarts, I am running a Quick Fuel carb, could be a Quick Fuel thing but everything i was able to find on the web all pointed to the same fixes, reduced pressure but maintaining flow volume at WOT
I might be a little over carbed (780 with vacuum secondaries) it will blow some dark greyish smoke/cloud at WOT but I'm hoping changing the air bleeds will help that, could just be my engine, original engine never been out of the car


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## PontiacJim (Dec 29, 2012)

AV68 said:


> Just a kinda for whats its worth, if you install a regulator with a mechanical pump use the dead head style or else the fuel pressure will constantly hunt not hold steady, I'm dealing with the hunting pressure right now using a return type regulator with a Edelbrock mechanical pump, I like the function of the return type regulator just to keep fuel constantly moving for cooler fuel temps. I cant remember where i read it but traditionally 6-7 psi for carbureted is what you wanted but modern fuels needed 3-4 psi to work better with carbs, so most fuel pumps will need a regulator of some kind


The factory 1967 spec for non-AC cars is 5-61/2 psi at 1,000 RPM's. AC cars are 3 - 5 1/2 psi at 1,000 RPM's. The AC cars had the return line to the tank, so you can see the difference it makes. Note this pressure is at 1,000 RPM's. Below that the pressure is less because that pump is not pumping very fast to make the higher pressures.

There is no difference between modern fuel pressure requirements and old school fuel pressure requirements. The difference may be with the carb type, needle/seat type and size, return line, and even gas line diameter.

Some larger carb, dual quads, and bigger cubic inch and HP engines require more fuel than a stock pump can provide. That's where you get into electric pumps and gallons per hour flow rates, larger fuel line sizes, BUT, you still need to have a regulator to provide the manufacturer's maximum or required fuel pressures.

Seems a number of the replacement/aftermarket fuel pumps do have more than stock pressures and need a regulator so they do not over-power the needle/seat and push gas past it.

You look for more gallons/per/hour over fuel pressure. Better to have more GPH at a low pressure than high fuel pressure and low GPH flow.

So many variables to be considered - not just as simple as going to NAPA as it was in 1975 and getting a correct replacement AC Delco fuel pump that you simply installed and went about your business.

Picture 1 & 2 - are examples of a fuel pressure regulator/return line set-up.

Picture 3 - is using an electric pump to prime the carb, or get the gas to the carb - like starting it. But, you can see that the pump has a bypass line that allows you to shut off the pump and let the factory fuel pump draw gas from the tank as it normally would. How is this possible? Look at the check valve in the system. When you activate the electric pump the line is pressurized and closes off the bypass line so it can only send fuel forward to the carb. Once the pump is shut down, the pump itself becomes the shut off valve and gas is drawn past the check valve via the mechanical fuel pump on the engine and providing a normal flow of gas from the tank.

Picture 4 - If you have an electric fuel pump, you want to have a pressure switch shut off wired up so it kills the pump when the engine is shut down - just in case you had a few nips of the 'ole moonshine keg and you shut the key off, but forgot to flip the off switch to the fuel pump (if you run it constant in place of a mechanical pump or as a helper pump).


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## coyote595 (Dec 4, 2019)

I am running a Carter M4868 from Rockauto. I installed it 8 months ago and it has been working well with no problems.


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## Bob66 (Oct 31, 2021)

I have a 66 GTO with the Tri-Power , added the fuel / vapor return line. Took my regulator off, switch to none ethanol fuel 93 octane. Stock mechanical fuel Pump A/C Delco , runs Great.


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## 64Original (Jun 21, 2017)

armyadarkness said:


> Myself and a few of the other people here (I think Bear and Lemans Guy?), run the Edelbrock. It's clockable and put's out exactly 6psi (depending on the model you get). Plus it's just a rebuildable, pro pump, which has greater volume capacity and it rebuildable.


I am running an Edelbrock as well but thinking about switching over to a RobbMC on the new stroker motor. It looks more like a stock pump and all the reviews seem to be favorable towards them.


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## Duff (Jan 12, 2020)

I REALLY miss the 70's, when 99% of auto parts actually fit and worked as designed, nowadays, you need to be part blacksmith, machinist, fabricator and a Hot Rodder, just to keep an old car running. I'm an old guy, and sometimes I think, maybe it's time to sell my cars and get back to fishing & hunting. Am I the only one thinking about this?


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## PontiacJim (Dec 29, 2012)

Duff said:


> I REALLY miss the 70's, when 99% of auto parts actually fit and worked as designed, nowadays, you need to be part blacksmith, machinist, fabricator and a Hot Rodder, just to keep an old car running. I'm an old guy, and sometimes I think, maybe it's time to sell my cars and get back to fishing & hunting. Am I the only one thinking about this?


Yep, it really takes the wind out of your sails sometimes. It should not be as difficult as it is sometimes. I guess the age of our cars really puts them into the "hot rod" class were you can't get the parts we used to and what parts you do get need some kind of fitting or adjusting to use - if you can use them. Very sad. I guess us "older" guys fight to keep them fairly original, but like the hot rods, the engines/transmissions/rear ends/brakes/suspensions will give way to newer upgrades that same way the flathead engines/Lincoln-Zephyr geared transmissions/quick-change rears, and wishbone suspensions had to go. It's just life as all things become obsolete at some point because technology changes/improves and upgrading to things that you can get current parts for pushes to the side those things you can't readily get parts for - or have to have deep pockets to purchase.

It is also generational. If you grew up with Honda's & Toyota's & LT and LS small blocks, you would not feel as you do because they are todays cars to build and hot rod.


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## lust4speed (Jul 5, 2019)

Photo is a 6" (as in half a foot) diameter Marsh gauge that had been recently calibrated. Fuel pump being checked was an off the shelf Airtex mechanical pump for the Pontiac and advertised as 6-1/2 pound output. Carb floats couldn't hold pressure at idle and after checking we knew why.


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## Duff (Jan 12, 2020)

PontiacJim said:


> Yep, it really takes the wind out of your sails sometimes. It should not be as difficult as it is sometimes. I guess the age of our cars really puts them into the "hot rod" class were you can't get the parts we used to and what parts you do get need some kind of fitting or adjusting to use - if you can use them. Very sad. I guess us "older" guys fight to keep them fairly original, but like the hot rods, the engines/transmissions/rear ends/brakes/suspensions will give way to newer upgrades that same way the flathead engines/Lincoln-Zephyr geared transmissions/quick-change rears, and wishbone suspensions had to go. It's just life as all things become obsolete at some point because technology changes/improves and upgrading to things that you can get current parts for pushes to the side those things you can't readily get parts for - or have to have deep pockets to purchase.
> 
> It is also generational. If you grew up with Honda's & Toyota's & LT and LS small blocks, you would not feel as you do because they are todays cars to build and hot rod.
> [/QUOTE I totally agree with your points, I guess us old guys, are the next generation to disappear, (remember the Model T crowd) but our cars will be mostly retrofitted and live on. It's odd, but I've been hankering for a 1950's or maybe older vehicle, something simple, but once again there will be parts issues. I'll have to figure it out, but maybe I'm getting tired of owning / maintaining a 1960's muscle car and all the HP issues associated with keeping it going, after all, I could still go to the car shows and relive some memories, just a thought.


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## Duff (Jan 12, 2020)

lust4speed said:


> Photo is a 6" (as in half a foot) diameter Marsh gauge that had been recently calibrated. Fuel pump being checked was an off the shelf Airtex mechanical pump for the Pontiac and advertised as 6-1/2 pound output. Carb floats couldn't hold pressure at idle and after checking we knew why.
> 
> View attachment 149920


I think that's also what's happening to my Q jet and Holley carbs, I hope to check the pressure today. Thanks for posting!


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## lust4speed (Jul 5, 2019)

I've found that Holley carbs will be okay up to 7-1/2 PSI but no reason to push it that far. Early Quadrajet limit is 6 PSI and later ones with the longer float arms will go up to 7, and AFB's good for 7. Tri-Power limit should be 4-1/2. Not hard and fast rules but will usually keep you out of trouble.


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## armyadarkness (Dec 7, 2020)

Duff said:


> I REALLY miss the 70's, when 99% of auto parts actually fit and worked as designed, nowadays, you need to be part blacksmith, machinist, fabricator and a Hot Rodder, just to keep an old car running. I'm an old guy, and sometimes I think, maybe it's time to sell my cars and get back to fishing & hunting. Am I the only one thinking about this?


If I had a nickle for every time that I considered trading in for a new Vette... but like they say, if it were easy, everyone would be doing it. 

I am shocked at how temperamental old cars seem to be... In the 80's, we just ran the wheels off of them... now they require baby bottle feeding... but much of that is just because we can no longer buy good old American parts.


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## Duff (Jan 12, 2020)

I checked the fuel pressure today, 8 psi, I'll be adding a regulator or a Edelbrock pump or maybe both.


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## Duff (Jan 12, 2020)

lust4speed said:


> Photo is a 6" (as in half a foot) diameter Marsh gauge that had been recently calibrated. Fuel pump being checked was an off the shelf Airtex mechanical pump for the Pontiac and advertised as 6-1/2 pound output. Carb floats couldn't hold pressure at idle and after checking we knew why.
> 
> View attachment 149920


I checked mine today with a KD Tool pressure gauge, it showed 8 psi, my car is running extremely rich, I THINK my pump came from Summit, probably a Carter.


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## AV68 (Aug 18, 2021)

Use a dead head style regulator if you do add one with the mechanical pump


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