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Author Topic: Fuel pump lever spring pressure seems excessive  (Read 1500 times)

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Offline squidtone

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Fuel pump lever spring pressure seems excessive
« on: September 27, 2020, 09:35:40 PM »
Hi folks,
When I first got my L134 running, I had to buy a new fuel pump. I got a fuel/vacuum style pump as is appropriate for a 50 CJ3A. I think the part number was actually for a CJ3B, but it fits up perfectly and I adapted the vacuum lines to the wipers with no problem.
Anyway, I noticed it takes a huge effort to move the lever arm. This is the arm that sticks into the block so that the cam eccentric and move the arm up and down.
I was concerned but ran it thinking it must be normal.
When I took my engine apart for a rebuild, I noticed there is quite a bit of wear showing on the cam eccentric.
I don't know if this is normal or what.
Can anyone comment on whether they've noticed grooves in the cam eccentric from that fuel pump arm?
I'm not sure if I should swap to a lighter spring, or am I paranoid or what. My old pump was not original (and probably not rebuildable), so I don't know what might be normal.

A picture is attached but it's hard to see the wear. But it is grooved.
If you've got any comments, I'd appreciate it.
Dave Miles
Presently: � � � � � � � �
03 Rubicon,
50 CJ3A
Past:
01 XJ Cherokee,
87 XJ Cherokee,
85 XJ Cherokee,
83 CJ8,
81 CJ7

Offline Rus Curtis

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Re: Fuel pump lever spring pressure seems excessive
« Reply #1 on: September 27, 2020, 11:01:42 PM »
Not an expert!  But, I was really surprised at the spring pressure on the lever when I tried to move mine.  I suspect this is to keep the lever on the cam lobe vs. bouncing or floating - making the pump not function correctly.

As far as the wear on your lobe, I don't know.  I've never studied one to see what it looks like after having logged some miles on the engine.  How much ZDDP are you running in your oil?  We know that modern oils don't have enough to keep the tappet wear to a minimum.  I'm assuming this would benefit the pump lever too.
'54 CJ-3B "Green Gruntt"
Bantam T3-C

Offline scoutpilot

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Re: Fuel pump lever spring pressure seems excessive
« Reply #2 on: September 28, 2020, 06:06:10 AM »
You are experiencing normal spring tension. Does the pump arm have a slider on it?
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Offline squidtone

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Re: Fuel pump lever spring pressure seems excessive
« Reply #3 on: September 28, 2020, 01:26:14 PM »
Hmm, what is a slider?
The pump arm on this pump is constructed of probably 4 layers of steel to form the thickness necessary for the  "arm". The 4 layers did not stack that smoothly, and that was another concern. The 4-layer arm directly contacts the cam eccentric. Since the 4 layers are not that smooth, the point of contact is probably on one of the layers that stand proud, which means a small contact patch.
Perhaps I should do a very minor grind and polish?

As for ZDDP, I did not use any ZDDP additive. Just passenger car 10W-40. I've only just recently "schooled" myself on oils so I intend to use a 10W-30 "diesel" oil with an API rating of CJ-4 or even CK-4. These oils (at least the Motorcraft versions) have good levels of "ZDDP". (Too much ZDDP can be BAD too)

Dave Miles
Presently: � � � � � � � �
03 Rubicon,
50 CJ3A
Past:
01 XJ Cherokee,
87 XJ Cherokee,
85 XJ Cherokee,
83 CJ8,
81 CJ7

Offline OnlyOneDR

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Re: Fuel pump lever spring pressure seems excessive
« Reply #4 on: October 07, 2020, 03:42:46 PM »
Perhaps I should do a very minor grind and polish?

I would clean up that arm on the pump, for sure.
Searching for time to put it all together...
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2001 Nissan Frontier Crawler Adventure Rig

Offline Rus Curtis

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Re: Fuel pump lever spring pressure seems excessive
« Reply #5 on: October 07, 2020, 04:12:52 PM »
Hmm, what is a slider?

ST,
There's a pic of a pump with a slider on the arm here:
https://www.cj3b.info/Tech/FuelPump.html

About half way down.

I'm guessing your's doesn't have one.
'54 CJ-3B "Green Gruntt"
Bantam T3-C