[78w72]

Nothing wrong with using a primer pump for this type of issue if you have already changed everything for new... and dont want to invest any more time tracking down the cause.

2 days does seem like there could be more than just evaporation going on, especially at only 45°... but a pusher pump will be a fix or band aid to get around whatever the problem is.

Have you seen these pumps? Cheaper priced than the bigger carter electric pumps and quite a bit smaller. Read online of someone else using this for a primer pump, this one is cheaper than MSRP.

https://www.ebay.com/itm/28630334268...4&gad_source=1

[Shiny]

Originally Posted by 78w72

Nothing wrong with using a primer pump for this type of issue if you have already changed everything for new... and dont want to invest any more time tracking down the cause.

Difficulty of diagnosing the cause is the challenge here, not the time. If there was a non-invasive and simple way to measure the seal on the pump check valve, this thread wouldn't exist. Similarly, if there was a non-invasive way to directly measure fuel inside the carb bowl, it would help. I measured my carb temperature, it's not excessively hot.

2 days does seem like there could be more than just evaporation going on, especially at only 45°... but a pusher pump will be a fix or band aid to get around whatever the problem is.

It takes a long time to cool down after shutting off so the residual heat is certainly a big contributor.

Several on the forum with direct knowledge and years of experience have chimed in and convinced me it's normal and it's evaporation.

A search found this 15-yr-old thread with the same info but lots of supporting statements:

https://forums.maxperformanceinc.com...ight=fuel+pump

I will say CO gas is now regulated to a lower RVP... like 7 to 9, depending on how the rules get bent.

Also, my car is filled with ethanol-free gas. I have no facts, but perhaps it is more volatile than typical pump gas ?? Anyone ??

Have you seen these pumps? Cheaper priced than the bigger carter electric pumps and quite a bit smaller. Read online of someone else using this for a primer pump, this one is cheaper than MSRP.

https://www.ebay.com/itm/28630334268...4&gad_source=1

Thank you for the link. That's a good price for a name-brand solenoid pump.

I'm going to use one of the Purolator/Facet Cube pumps shared earlier in the thread by Kenth. I won't be doing this for a couple months but that's the plan.

Mike

[grivera]

Originally Posted by 78w72

Have you seen these pumps? Cheaper priced than the bigger carter electric pumps and quite a bit smaller. Read online of someone else using this for a primer pump, this one is cheaper than MSRP.

https://www.ebay.com/itm/28630334268...4&gad_source=1

Will a pump like this free-flow when not activated? To be used as a primer pump only?

[HWYSTR455]

This entire thread is why I gave up and went efi.

Even if it's tbi, the 'owner experience' is just 'better'.

I suspect it's the same reason the OE engineers went that direction too, because carbs are certainly cheaper.


.

[grivera]

Originally Posted by HWYSTR455

This entire thread is why I gave up and went efi.

Even if it's tbi, the 'owner experience' is just 'better'.

I suspect it's the same reason the OE engineers went that direction too, because carbs are certainly cheaper.


.

I think both still have their place - the EFI in my bird has been great ever since I ironed out issues - it wasn’t always the case and has left me stranded. My concern with non-OEM EFI is if one breaks down it is definitely a tow home or to a shop - you ain’t fixing the computer on the side of the road. Assuming one uses points and all other factory replacement type parts, you can usually repair on the side of the road. Same with an in-tank pump - if that fails you will likely not have a spare for replacement and even if you do, you need to have an access door in the trunk like Larry (FormulaJones) has.

[Formulajones]

EFI isn't a bad way to go. It does present a possible road side scenario I guess if you happen to have an important sensor fail.
I have mine setup for certain scenarios just in case. As grivera mentioned I run a trap door in the trunk literally making fuel pump swaps a 30 minute deal.
I also keep a open loop tune in the program so the car runs without an O2 sensor. So if that fails and AFR's go wonky I simply load that tune and drive away.
Other sensors like TPS or CTS probably won't leave you stranded but keeping spares are easy enough if you desire.
Keep in mind the need to change an in tank pump is extremely rare. Millions of cars on the roads today use them, in fact I'd bet everyone here has a car in the fleet with it and don't even think twice about it. So this shouldn't be a huge concern for anyone really.
02 sensors can occasionally fail but if installed properly I find that to be a rare issue as well. They usually have problems when horrible tuning practices are used, bad placement, things like that.

I don't believe EFI should be considered a solution for other problems one is having like this whole fuel issue. As I've stated many times both of our dailys are carb and points and simply don't have these problems. EFI in many cases I've seen come through here have their own new problems, primarily from horrible installs, terrible fuel system setups, wiring that looks like a rats nest, 99 percent of this stuff being self inflicted. Which helps me to understand why one had carb problems in the first place lol.
Unfortunately it then gives EFI an undeserving bad rap. But EFI is pretty nice when done properly.

[HWYSTR455]

I've had that Terminator tbi setup on the 442 since like 2012, no issues. I drove that thing after a partial resto on the Power Tour. It was in my driveway for a while due to a module failure in the dual sync (FAST distributor), replaced it and drove it from my old house to my son's house which is an hour 45 min away. With crappy old gas in it too.

Holley uses (for the most part) GM sensors, so they are reliable. I do have a spare set for times of troubleshooting or long drive toolbox mode.

If you're running a mech pump on your Pontiac, pretty doubtful you will find a replacement at an auto parts store, that stuff just isn't stocked by most. And you still have to make it from a roadside to a parts store.

I don't carry a spare tire, so if i get a flat, I flatbed it home anyway. So I'm prepared to do so. I didn't want to put a door in the trunk so if a pump goes bad, I just drop the tank.

Usually when pumps go bad it's not an on/off thing, it slowly starts flowing less and less. You start getting bogs etc, so you can usually limp it home.

I ran carbs for years in the LeMans, and drove up & down the east coast and more, rarely had a problem, but most of that time I had an elec pump. I did at one point have an issue with an HEI that was eating coils, and carried coils with me, but eventually switched to an aftermarket unit. Problem solved.

It can go either way with a mech pump/carb or efi, so it's hard to make that argument. But I do understand some not wanted to switch. Me personally, I won't go back.


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[Shiny]

I don't know about the Edelbrock pump but the Facet pumps as shared by Kenth allow flow-through when they are off. Edelbrock is probably the same.

Here are the Facet pumps (multiple lines) that allow flow-through:

https://www.pegasusautoracing.com/gr...ID=FACETSIPHON

I don't know how much of a restriction they will introduce, but it won't be zero. So these pumps may not make sense for high HP fed by a mechanical pump. For my car, unlikely to be an issue. I suppose you could always leave them running as long as they flow enough to support your engine.

These solenoid-style pumps apparently have relatively tight internal tolerances on wetted parts so they recommend a pre-screen filter. Facet sells a 70 u version that looks just like the filter with the Edelbrock pump. I don't like the setup using a rubber hose in a fuel line, so if I use a filter, it will probably be something with NPT fittings on both ends, like this, assuming the mesh is coarse:



The Facet pumps (at least the Cube line) can also be configured to block flow when they are off, but that wouldn't make sense as an inline primer for a mechanical pump:

https://www.pegasusautoracing.com/gr...ID=FACETSIPHON

Either the "Posi-Flow" or the "Cube" lines should work as a primer pump. There are more options available on the Cube line and they look like they are built well. I like the ability to choose max pressure and the claim of "self regulating". I think any solenoid pump will be self-regulating when dead-headed, but the range of available max pressures on the Facet line is more comforting than a generic claim of "5 to 7 psi" on many of them. I am squeamish about over-pressuring my carb and causing it to flood. This is apparently a common concern with mechanical pumps that also claim to have a 5 to 7 psi max but are then reported to deliver 10.

Mike