seany-boy,
What do you mean "check the valve in the fuel pump after rebuild?" I installed the valves and staked them per the Then and Now youTube video. Should I have done something more?
Rusty, I did not install the new lever pin that came with the rebuild kit. I did not detect any play in the lever assembly. Do you think I should go back and replace the pin?
Thank you both for your comments and suggestions.
Jim Yergin
Fuel problem
Moderator: Joe Johnston
Re: Fuel problem
Hi Jim,
seany-boy has a good point about check valves. Now that I read his post I agree that the inlet check valve could be an issue. The fact that you have pressure means that the output check valve is working.
I suggest that you connect your vacuum gauge to the inlet side while you run the car on the separate fuel feed.
More later!
seany-boy has a good point about check valves. Now that I read his post I agree that the inlet check valve could be an issue. The fact that you have pressure means that the output check valve is working.
I suggest that you connect your vacuum gauge to the inlet side while you run the car on the separate fuel feed.
More later!
Rusty
VTCI 13079
VTCI 13079
Re: Fuel problem
Hi Jim,
I read you had seated them correctly, just an area to double check incase it has come loose or faulty. A vac gauge as Rusty suggests is a great investment if you don't have one.
I read you had seated them correctly, just an area to double check incase it has come loose or faulty. A vac gauge as Rusty suggests is a great investment if you don't have one.
Red 57 Thunderbird 312 3spd O/D
Location: Melbourne, Australia
Location: Melbourne, Australia
Re: Fuel problem
Someone check my thinking on this.. I'm not seeing how some slight amount of wear is going to cause a problem. When the pump is installed the arm always has pressure on it, its not like a rocker arm with clearance between it and the valve stem, it's always tight against the cam, at least I think it is. Since it's tight any slight wear is compensated for.
As to the flow rate.. The spec flow rate, 1 pt per 30 seconds, if fully used is enough fuel at 6o mph to get a gas mileage of 4 mile per gallon. So half that, 1/2 pint per 30 seconds, would be 8 miles per gallon. If there seems to be a fuel starvation problem at idle and cruising speeds where you would expect to get 10+ mile per gallon 1/2 pint per 30 seconds should be enough.. might not be enough if running at the drag strip though.
As to the flow rate.. The spec flow rate, 1 pt per 30 seconds, if fully used is enough fuel at 6o mph to get a gas mileage of 4 mile per gallon. So half that, 1/2 pint per 30 seconds, would be 8 miles per gallon. If there seems to be a fuel starvation problem at idle and cruising speeds where you would expect to get 10+ mile per gallon 1/2 pint per 30 seconds should be enough.. might not be enough if running at the drag strip though.
Re: Fuel problem
Sorry for the delay.
There are multiple places for wear in the linkage. I agree that the pin itself probably wears the least. It is the hardest part in the pivot mechanism. The holes in the pump body as well as the hole in the arm itself will wear more. The pump body is just aluminum die cast material so it is pretty soft. The material for the pump arm varies but is typically harder than the body but softer than the pin.
The pump arm is softer than the eccentric ring so it will wear. As Jim stated earlier that could be the reason for a reduced stroke. That definitely will reduce the volume delivered. About the only way I know to check that is to find a new pump arm and compared them. Not easy to do.
I have never worked on a fuel pump on Y-block. Based on what I have read it can be a little tricky to get the fuel pump arm properly engaged with the eccentric. What is new to me is that on these engines the eccentric ring is a separate part that bolts to the front of the cam. I don’t know if it can become loose or wears so much that the pump stroke is reduced.
There are multiple places for wear in the linkage. I agree that the pin itself probably wears the least. It is the hardest part in the pivot mechanism. The holes in the pump body as well as the hole in the arm itself will wear more. The pump body is just aluminum die cast material so it is pretty soft. The material for the pump arm varies but is typically harder than the body but softer than the pin.
The pump arm is softer than the eccentric ring so it will wear. As Jim stated earlier that could be the reason for a reduced stroke. That definitely will reduce the volume delivered. About the only way I know to check that is to find a new pump arm and compared them. Not easy to do.
I have never worked on a fuel pump on Y-block. Based on what I have read it can be a little tricky to get the fuel pump arm properly engaged with the eccentric. What is new to me is that on these engines the eccentric ring is a separate part that bolts to the front of the cam. I don’t know if it can become loose or wears so much that the pump stroke is reduced.
Rusty
VTCI 13079
VTCI 13079
Re: Fuel problem
If the pump is installed at TDC there should be no problems and the wear should be minimal. The pump is producing pressure so no issue there. it's how much fuel is available to the pump. I'm not a big fan of axillary pumps. My rebuilt AC provides so much more performance, my wipers run fast and had to snug down my carb and line fittings to compensate for the added pressure. All stock and works great. Nothing wrong to let it crank to build oil pressure before it fires off. Even sitting for a few days just setting the choke and a turn of the key it fires right off and purrs. I guess I'm lucky.
VTCI # 13223
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Jim Yergin
- Posts: 137
- Joined: Thu May 21, 2015 2:56 pm
Re: Fuel problem
I have a vacuum gauge and will check the inlet side as suggested. What sort of reading should I be looking for?
Thanks.
Jim Yergin
Thanks.
Jim Yergin
Re: Fuel problem
Hi Jim,
I knew you were going to ask that question! Few if any shop manuals list that spec.
My limited experience is that a mechanical fuel pump probably will pull about 4-5” hg. That is equivalent to the fuel tank being pressurized to 2-2.5 psi.
I knew you were going to ask that question! Few if any shop manuals list that spec.
My limited experience is that a mechanical fuel pump probably will pull about 4-5” hg. That is equivalent to the fuel tank being pressurized to 2-2.5 psi.
Rusty
VTCI 13079
VTCI 13079
Re: Fuel problem
sorry about the delay, I am having a lot of issues with login and posting at present.
Jim, I noted that you said you ran the engine on the electrical pump but did you run the car up an incline with just the electrical pump operating? This is the first thing I would try to do before I ripped the mechanical one out. It is important to test it in the same scenario as , from experience, you can spend a lot of time chasing your tail with these type of faults.
If you can this would prove the pump/supply is or is not the issue you are chasing, or conversely the carb is or is not...
Jim, I noted that you said you ran the engine on the electrical pump but did you run the car up an incline with just the electrical pump operating? This is the first thing I would try to do before I ripped the mechanical one out. It is important to test it in the same scenario as , from experience, you can spend a lot of time chasing your tail with these type of faults.
If you can this would prove the pump/supply is or is not the issue you are chasing, or conversely the carb is or is not...
Red 57 Thunderbird 312 3spd O/D
Location: Melbourne, Australia
Location: Melbourne, Australia
-
Jim Yergin
- Posts: 137
- Joined: Thu May 21, 2015 2:56 pm
Re: Fuel problem
seany-boy,
I appreciate the suggestion but doesn't the fact that I can drive up an incline with no problem when the electric pump is on accomplish the same thing?
Jim Yergin
I appreciate the suggestion but doesn't the fact that I can drive up an incline with no problem when the electric pump is on accomplish the same thing?
Jim Yergin
-
Jim Yergin
- Posts: 137
- Joined: Thu May 21, 2015 2:56 pm
Re: Fuel problem
Rusty,
According to my vacuum gauge the mechanical fuel pump has 11 in hg at idle. Does that mean the inlet check valve is OK?
Jim Yergin
According to my vacuum gauge the mechanical fuel pump has 11 in hg at idle. Does that mean the inlet check valve is OK?
Jim Yergin
Re: Fuel problem
Wow! That is impressive. There are no issue with that check valve. That would probably collapse a tank that was not vented correctly.
Thanks for checking that.
Earlier today I saw a post in the '55-'57 Facebook page. The person had a similar fuel supply complaint. The discussion focused on the inside diameter of the inlet fuel hose. The posts were noting that replacement hoses were typically smaller than the 1/4'" original hose. Think of it this way. A 3/16 inlet hose is only 56% of the inlet area of the 1/4' hose.
This restriction can also occur if the existing hose starts to swell internally over time.
Thanks for checking that.
Earlier today I saw a post in the '55-'57 Facebook page. The person had a similar fuel supply complaint. The discussion focused on the inside diameter of the inlet fuel hose. The posts were noting that replacement hoses were typically smaller than the 1/4'" original hose. Think of it this way. A 3/16 inlet hose is only 56% of the inlet area of the 1/4' hose.
This restriction can also occur if the existing hose starts to swell internally over time.
Rusty
VTCI 13079
VTCI 13079
Re: Fuel problem
HI JIm,
Yes you are correct. I missed that you could drive up the incline with the electric pump, I thought you had just tested it separately. I would still do a quick check on the valves in the pump if you have not double checked. Mine seemed to bounce out either under pressure or due to bumps and then reseat themselves.good luck.
Yes you are correct. I missed that you could drive up the incline with the electric pump, I thought you had just tested it separately. I would still do a quick check on the valves in the pump if you have not double checked. Mine seemed to bounce out either under pressure or due to bumps and then reseat themselves.good luck.
Red 57 Thunderbird 312 3spd O/D
Location: Melbourne, Australia
Location: Melbourne, Australia
Re: Fuel problem
wasn't there a tech tip to slightly swedge the sides to hold the valve in place. I wouldn't trust just a friction fit.seany-boy wrote: ↑Thu Jun 02, 2022 5:08 pm HI JIm,
Yes you are correct. I missed that you could drive up the incline with the electric pump, I thought you had just tested it separately. I would still do a quick check on the valves in the pump if you have not double checked. Mine seemed to bounce out either under pressure or due to bumps and then reseat themselves.good luck.
VTCI # 13223
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Jim Yergin
- Posts: 137
- Joined: Thu May 21, 2015 2:56 pm
Re: Fuel problem
Rusty,
I have replaced the original flexible fuel output line with an ethanol resistant hose that I believe has the correct diameter but I can check it out.
Ward 57,
I did stake the valves as directed by the Then and Now video.
At this point I have ordered another pump rebuilt by someone else. If the problem still exists then I think I will have to decide whether to live with the problem and rely upon the electric pump when needed or remove the timing chain cover and check the pump eccentric.
Jim Yergin
I have replaced the original flexible fuel output line with an ethanol resistant hose that I believe has the correct diameter but I can check it out.
Ward 57,
I did stake the valves as directed by the Then and Now video.
At this point I have ordered another pump rebuilt by someone else. If the problem still exists then I think I will have to decide whether to live with the problem and rely upon the electric pump when needed or remove the timing chain cover and check the pump eccentric.
Jim Yergin