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I was working thru a fuel pump issue that led to a sticky fuel pump rod so I decided to start a new post.
The fuel pump rod on my LS Vette is VERY sticky, it must be tapped back up to touch the cam lobe. The engine only has a few hours on it but has been sitting a fair amount over the last eight years or so.
I have done a bit of research and have tried working it back and forth while spraying with penetrating oil. I’ve also tried with several types of specialty needle nose pliers with no success. Short of disassembling part of the engine what are my option to remedy?
What’s interesting is that it was free to move when I replaced the fuel pump.
KC
Last edited by grumman41; Jul 22, 2024 at 01:25 PM.
Reason: Pictures
Didn't you say you greased it to get it to stay during assembly? Can you still remove it now? I'd start by checking for roundness and symmetry with calipers.
One option is to abandon the fuel pump rod, and switch to an electric fuel pump solution.
Is it possible it was put in place with white lithium grease years ago? That grease will harden over time. Can you put an inspection camera in the cavity and see what is causing the problem.? Jerry
The engine was built over eight years ago by a very reputable builder but I don’t know how he greased the rod. I’ve never had the rod completely out but did work it down some and put a dab of tacky fuel lube to hold it up. I’m guessing this was my issue with fuel pressure and not the pump itself. The car is very original so I’m committed to working thru this and running the mechanical pump.
Im think the resistance on the rod was stronger than the fuel pump spring so it wasn’t getting a full stroke. The resistance to get the rod back up to the cam profile takes a tap of the hammer, not something I can do with my finger.
By chance did you install a bronze end fuel pump rod?
When they wear which is rapidly, they mushroom on their end and become difficult to remove.
I did a post on using polymer rods and never have a problem or flat pump cam lobe
I just had to remove my polymer fuel pump rod and go electric pump due to pump lobe cam wear. Lunati cam. Ran 10 years then started starving for fuel at high RPM's. After much trouble shooting, different pumps etc, I finally measured the throw of the lobe, only .220". New should be around .330".
So I'm not sure the polymer rod is THE answer, it did run 10 years however.
I don’t know the specs on the rod material as we didn’t discuss that at the engine build. From what I can tell from looking with a flashlight it looks like steel not bronze. My power symptoms sounds just like reelav8trs. My current plan is to turn the starter until full rod extension, soak with PB Blaster, and then tap back up to the cam. Rinse and repeat until I get too old to drive this Vette or you guys come up with a magic fix.
Im totally out of ideas and at your mercy!
KC
The bronze tip is on a hollow steel tubing shaft. Maybe a 1/4 inch thick.
SBC's have a bolt from the front of the block. A longer bolt can stop the pump rod from sliding in when you install the cam. Then you put a short bolt which is a oil seal
With your fuel pump on the garage floor or work bench, it should take considerable effort to force the arm down with your hand.
More importantly, it should return upward easily. (caution, it will shoot gas everywhere)
Do you have a bolt at the front to hold the pushrod in the block now? If someone installed a too long of bolt you will see the threads coming thru into the pump rod tunnel.
There are so many pump pushrods on the market today with different materials on the tip. Each material is designated for a certain type of cam material.
It gets very confusing. Steel, billet, iron, carbon tipped and bronze, etc. And those specialty pushrods can only go in one way without damage.
If you have a micrometer, maybe you could check the tip of the pushrod for "mushrooming".
Last edited by HeadsU.P.; Jul 23, 2024 at 06:49 PM.
This is an LS5 454 BB guys.
No pushrod bolt hole there.
New info from above:
it should have .330" throw.
Now the real question is can you grab it with a strong enough magnet then? Or long needle-nose?
Anyone have a bare BB block laying around that they could shoot a pic of both sides of the push-rod hole?
I just had to remove my polymer fuel pump rod and go electric pump due to pump lobe cam wear. Lunati cam. Ran 10 years then started starving for fuel at high RPM's. After much trouble shooting, different pumps etc, I finally measured the throw of the lobe, only .220". New should be around .330".
So I'm not sure the polymer rod is THE answer, it did run 10 years however.
That is not good news!
What type of cam core? HR? Flat? Billet? iron dizzy gear? etc.
What type of cam core? HR? Flat? Billet? iron dizzy gear? etc.
No its not,
Im using a polymer rod based on his a Gkulls advice to do so. im assembling a 406 now to swap in which also has a retro roller cam so I'd like to avoid future issues in this regard. I have a bronze tipped rod too which I had in th car for a few months before swapping, it had no mushrooming but clearly had low use.
I don’t know the specs on the rod material as we didn’t discuss that at the engine build. From what I can tell from looking with a flashlight it looks like steel not bronze. My power symptoms sounds just like reelav8trs. My current plan is to turn the starter until full rod extension, soak with PB Blaster, and then tap back up to the cam. Rinse and repeat until I get too old to drive this Vette or you guys come up with a magic fix.
Im totally out of ideas and at your mercy!
KC
Bronze tipped look like regular steel rod except a 1/8" thick bronze cap on the end that ride on the cam lobe.
I had a Comp Cams h-roller fuel pump lobe vanish, but it took 5000 miles using a lighter weight steel rod. I had a bronze mushroom when I had to rebuild my motor with under 2500 racing miles.
It really comes down to the quality of the cam. I quit using hardened camshafts and went to billet steel cams with a sleeved on dizzy gears and polymer pump rods. I had considered roller tips .
This is an LS5 454 BB guys.
No pushrod bolt hole there.
New info from above:
it should have .330" throw.
Now the real question is can you grab it with a strong enough magnet then? Or long needle-nose?
Anyone have a bare BB block laying around that they could shoot a pic of both sides of the push-rod hole?
I think the reference of .330” throw came from auggie, who, I thought runs a small block. Is it same for big block?
I think the reference of .330” throw came from auggie, who, I thought runs a small block. Is it same for big block?
Actually it was REELAV8R
Originally Posted by REELAV8R
I just had to remove my polymer fuel pump rod and go electric pump due to pump lobe cam wear. Lunati cam. Ran 10 years then started starving for fuel at high RPM's. After much trouble shooting, different pumps etc, I finally measured the throw of the lobe, only .220". New should be around .330".
So I'm not sure the polymer rod is THE answer, it did run 10 years however.
I had a Comp Cams h-roller fuel pump lobe vanish, but it took 5000 miles using a lighter weight steel rod. I had a bronze mushroom when I had to rebuild my motor with under 2500 racing miles.
It really comes down to the quality of the cam. I quit using hardened camshafts and went to billet steel cams with a sleeved on dizzy gears and polymer pump rods. I had considered roller tips .
Good data point GKull!
So do you have any experience with the longevity of a Billet roller cam with a polymer pushrod combo?
Good data point GKull!
So do you have any experience with the longevity of a Billet roller cam with a polymer pushrod combo?
Multiple rebuilds on two billet steel cams and using poly pump rods in both engines over the past 15 years. I have the AC-Delco stock type fuel pumps with the return line.
With the return line I only have say under 6 PSI of fuel pressure for the past 30 years. When t he cam lobe went away I thought that i had a pump problem and bought a new one, It put a lot of metal in the engine 383 at the time so I yanked it out and went to my 427 and tried bronze on billet steel which was a bad move. Bothe engines then got poly rods
Sticky fuel pump rod
