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MarkS57 · 09-05-2023, 02:40 PM

Has anyone had issues with this pump? Bought new in March and just stranded me last Friday. It's a 2-line pump that works well early GTO's etc. After pulling the pump, it seems the arm is completely disconnected from the diaphragm. Just flops around, no spring pressure at all. I would do a further autopsy but at least Rock Auto is going to replace it under warranty and want it back so no cutting it open.

68bird400HO · 09-05-2023, 02:49 PM

Yup, same problem I had. Arm broke because I believe they are using the wrong arms on these replacement pumps now. See my thread from about a month ago.

https://forums.maxperformanceinc.com...d.php?t=868529

MarkS57 · 09-05-2023, 06:05 PM

Quote:

Originally Posted by 68bird400HO

Yup, same problem I had. Arm broke because I believe they are using the wrong arms on these replacement pumps now. See my thread from about a month ago.

https://forums.maxperformanceinc.com...d.php?t=868529

Wow, depressing read. Good point about the arm. I just received the replacement from Rock Auto today (but it's not going in). I have an Airtex that's several years older than this new one, it's basically the same but it has an inverted flare fitting in place of the 1/4" FNPT. Guess what? the arm on the older Airtex is at least a 1/4" lower than the new pump. I found an NOS M4566 on ebay. It's in a Federal Mogul / Carter box & actually has "AC" in the casting. I am very thankful for this forum, if I hadn't posted about my pump issue, I'd be installing the replacement POS pump right now.

Thanks!!

67drake · 09-05-2023, 06:11 PM

Quote:

Originally Posted by MarkS57

Wow, depressing read. Good point about the arm. I just received the replacement from Rock Auto today (but it's not going in). I have an Airtex that's several years older than this new one, it's basically the same but it has an inverted flare fitting in place of the 1/4" FNPT. Guess what? the arm on the older Airtex is at least a 1/4" lower than the new pump. I found an NOS M4566 on ebay. It's in a Federal Mogul / Carter box & actually has "AC" in the casting. I am very thankful for this forum, if I hadn't posted about my pump issue, I'd be installing the replacement POS pump right now.

Thanks!!

Depends on just HOW old that Airtex pump is. If it was made before the manufacturer started using the ethanol resistant diaphragms, it might not last either.

Rugratman · 09-06-2023, 06:43 PM

Mine is pushing 11 lbs. Not the 6 quoted.

tstroud · 09-06-2023, 10:07 PM

Mine was also pushing almost 11 lbs pressure.
I put a regulator on it to keep the Q-jet happy.

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Rugratman · 09-07-2023, 06:42 AM

Did you hide your regulator?

tstroud · 09-07-2023, 08:18 AM

No. I plan on doing something different after I get all the other bugs worked out. So I put it in a convenient spot temporarily.

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Rugratman · 09-07-2023, 08:42 AM

I don't mind running a regulator. It's just ugly and all the extra hoses.

tstroud · 09-07-2023, 02:21 PM

Agreed. As soon as I’m sure all the fuel lines are clean I’ll probably get a RobbMC pump and ditch the regulator and in-line fuel filter.

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Dave M · 09-07-2023, 04:07 PM

I’ve got a RobbMc on my 71 which is a new build. And my son’s 79. Which had been working well since 2017. I’ve got a stock pump and an electric pusher on my 68 Firebird. Will probably replace that with a RobbMc as well. I just need the time and a place to swap it. Because, I will also be replacing stock line and pickup with a 1/2”

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MarkS57 · 09-14-2023, 11:13 AM

Quote:

Originally Posted by MarkS57

Wow, depressing read. Good point about the arm. I just received the replacement from Rock Auto today (but it's not going in). I have an Airtex that's several years older than this new one, it's basically the same but it has an inverted flare fitting in place of the 1/4" FNPT. Guess what? the arm on the older Airtex is at least a 1/4" lower than the new pump. I found an NOS M4566 on ebay. It's in a Federal Mogul / Carter box & actually has "AC" in the casting. I am very thankful for this forum, if I hadn't posted about my pump issue, I'd be installing the replacement POS pump right now.

Thanks!!

Update, finally got my NOS M4566 yesterday after it went missing in USPS for a few days. Seems to date to the early to mid 90's. I'm going to double down on the pump arm issue. No question this new arm is really preloading the diaphragm & probably pushing it beyond its designed travel limit. Leading to both early failures & maybe over pressure. I haven't checked the fuel pressure on the NOS pump yet but the car does seem to run much better at idle.

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