67 440 mechanical fuel pump low fuel output...

[GassMann]

Hey all,

I have a 67 440 with a Edelbrock 750. The pump seems like it is not putting out enough fuel. The engine idles fine. But rev it up and it starts to die. The pump is new but maybe not the right one for this application. The inline filter does not even fill up half full.

Suggestions on a replacement fuel pump?

 

[pnora]

Hey all,

I have a 67 440 with a Edelbrock 750. The pump seems like it is not putting out enough fuel. The engine idles fine. But rev it up and it starts to die. The pump is new but maybe not the right one for this application. The inline filter does not even fill up half full.

Suggestions on a replacement fuel pump?

I would see how much fuel it puts out into a container. You could have other issues like the fuel sock in the tank being plugged, crap in the tank, bad hoses or connections sucking air, or a worn push rod for the pump. If all those check out than depending on your existing pump connections any carter with less than 7PSI. would be fine.

 

[jimbosride]

Maybe also install a inline pressure gauge to start.

 

[khryslerkid]

Did you check your pushrod length. Lots of instances where the pushrod is worn down and it doesn't activate the pump.

 

[toolmanmike]

Pushrod is worn. Probably 1/2" shorter than a new one. It's a fairly common problem.

 

[Dave6T4]

I had a Carter pump on my '67 R/T that was acting up, giving the same symptoms you are experiencing. It turned out that the lever pin had slid part way out, allowing the lever to wobble around, rather than give full pump stroke. But you have new pump????

 

[Curiousyellow71]

The sock on the pickup in the tank can also cause a restriction...if it has one.

 

[Geoff 2]

Depending on the orientation of the filter, you can get an airlock inside it....but the pump is working ok.

 

[451Mopar]

Try bypassing the fuel tank and lines by just hooking a flexible fuel line to the pump inlet and the other end in a gas can.
If that fixes the problem, then you will need to check the lines and tank. Once, I found the rubber line that connects the fuel tank to the hard fuel line was partly split and allowing some air to get sucked into the line along with a small amount of fuel, so the engine would idle, but die out in gear.

 

[hofferwood]

Was the fuel pump replaced because of the same problem?
If so, the carb could be the source of your frustration.

 

[lewtot184]

Most stock replacement pumps are two valve 3-5 psi and more likely than not in the 3-4 psi range. The hipo 440 two valve pump is 8 psi but needs a vapor separater and return line. The Carter 6903 is a 5-6 psi pump but uses three valves and doesn't have to have return line. The 6903 may be the best choice.

 

[GassMann]

Pushrod is worn. Probably 1/2" shorter than a new one. It's a fairly common problem.

So I did not check the rod length. What length should it be?

 

[toolmanmike]

So I did not check the rod length. What length should it be?

3.22 I think. CHRYSLER 6.3L/383 Fuel Pump Pushrods - Free Shipping on Orders Over $109 at Summit Racing

 

[GassMann]

Was the fuel pump replaced because of the same problem?
If so, the carb could be the source of your frustration.

It is a full rebuild. New carb, new pump. Though I am thinking now that I didn't check to see if it was the right pump. I will have to do a flow test. I read it should put out about 110 gph but I don't know how much that works out to be per stroke or rotation of the crank. I highly doubt it's the carb but it very well could be the pump.

If I put the end of the fuel line in a cup... crank it for a few revs... how many ounces should I get roughly?

 

[hofferwood]

If I put the end of the fuel line in a cup... crank it for a few revs... how many ounces should I get roughly?

I don't know the ans. to that, but -------------if you do that, put out your smoke and unhook the - (neg) from your coil.
And that is what I was going to suggest. If you get just a dribble, unhook the supply line to the tank, take the gas cap off (or loosen it). then blow some compressed air back into the tank (to clear the sock in the tank).

 

[GassMann]

I put a new gas tank in and cleaned the sock so I doubt it's the sock. I know I am getting more than a dribble. Enough to see it flowing into the filter but it sure aint enough to run. It idles fine. But put the peddle down and it will stall... like it's starved of fuel. Under load... it dies. I can back it out of the driveway but not far.

 

[Geoff 2]

This is how you check the pump output:
- get engine up to operating temp & switch off
- disconnect the fuel line at the carb
- fill carb float bowls by filling them through the vents. Stop filling when you see fuel exiting the primary boosters [ carb is full of fuel ]
- dump the fuel hose into a 4 gal container
- start engine & run for 1 minute.
- you can now calculate the gallon per hr rate.

Take care with flammable fuel & an assistant is helpful.

 

[lewtot184]

I had a holley pump once that did something similar. Had pressure but not much gasoline. Never figured it out.

 

[GassMann]

This is how you check the pump output:
- get engine up to operating temp & switch off
- disconnect the fuel line at the carb
- fill carb float bowls by filling them through the vents. Stop filling when you see fuel exiting the primary boosters [ carb is full of fuel ]
- dump the fuel hose into a 4 gal container
- start engine & run for 1 minute.
- you can now calculate the gallon per hr rate.

Take care with flammable fuel & an assistant is helpful.

Excellent directions Geoff... I will give that a try. I did drop the line into a bottle and after 4 rotations (4 pumps), I got 2 oz or 1/2 oz per cycle out of the pump. Not sure if that is good or bad but it seems right. Of course, I did replace the filter. I had a reusable/cleanable filter (new) before... thought it looked cool.

I had some beige powder in the filter from the old fuel line... I think it would have been lead or maybe residue from years of fuel sitting in the old line. My one mistake was not replacing the fuel line from the tank to the engine.

Based on that, I checked the carb to see if it had a filter in it (as I have seen some of those type of metal filters inline before) but it did not. So I am not sure I solved the problem or not with a new filter.

Now I am back to square one. New filter, 1/2 oz per cycle seems right for fuel but now I will try your suggestion and run it for a min's. See how much fuel I get.