Fuel Pump

[akrvr]

Problem: sputtering, fuel starvation under a load. Fuel pump not working
Fix: new fuel pump
Problem: New fuel pump will pump with hand lever but not with engine turning
Answer: Add electric fuel pump
Problem: Electric fuel pump goes bad after 1 week (tick but no pump)
Fix: Napa replaced it, I installed it
Questions: (1) Is there any problem running the electric fuel pump in front of the mechanical one if the mechanical one is bad (2) why would a new pump prime by hand but not pump when engine is spinning? (3)Anyone ever heard of a cam lobe going bad?
Thanks!
1965 ExMOD 109

[gambrinus]

You installed a new mechanical fuel pump that didn't work?

These things are idiot-proof and don't usually provide any problems...

More details?


RW

[SafeAirOne]

Did you ensure that the cam follower arm on the fuel pump is on the correct side of the camshaft? Usually they'll only fit on the correct way, but you never know...

I'd think that the correct fix for a defective NEW mechanical fuel pump would be to have a replacement sent from the folks you bought the bad one from (or get your money back and find a proper replacement)!

Electric fuel pumps are usually installed upstream of the mechanical fuel pump. They should be able to pump through the mechanical pump.

I doubt very much that you've worn the fuel pump cam lobe down to a point where it won't actuate the pump.

[bkreutz]

Problem: sputtering, fuel starvation under a load. Fuel pump not working
Fix: new fuel pump
Problem: New fuel pump will pump with hand lever but not with engine turning
Answer: Add electric fuel pump
Problem: Electric fuel pump goes bad after 1 week (tick but no pump)
Fix: Napa replaced it, I installed it
Questions: (1) Is there any problem running the electric fuel pump in front of the mechanical one if the mechanical one is bad (2) why would a new pump prime by hand but not pump when engine is spinning? (3)Anyone ever heard of a cam lobe going bad?
Thanks!
1965 ExMOD 109

Answers:
1, Theoretically no, but I would bypass it just to eliminate the possibility of a ruptured diaphragm filling the crankcase with fuel.
2. Bad cam lobe would do it, but highly unlikely considering the force exerted by the pump on the lobe compared to the valve train. If the hand prime works and the engine spinning doesn't, I'd suspect the arm on the pump has either bent from being weak or bent because of a crack in the arm. I've seen this a number of times in my 43 years of being a mechanic. (BTW I have seen 1 bad cam lobe in that same time frame) Since the engine actuating arm and the hand priming lever are operating the same diaphragm and valving, you've eliminated everything in the pump except the arm (and it's pivot) that extends into the engine.
As an aside, are you sure your sputtering under load is due to lack of fuel? One way to be sure is to use a propane torch with a hose on it, tape the open end of the hose over the carb throat, when it starts to sputter, turn on the propane, if the problem goes away or significantly improves, I'd be looking elsewhere for a problem. The reason I bring this up is that a bad condenser in the ignition will give those exact symptoms. Fooled me a once a long time ago (3 fuel pumps and 2 carbs later) never forgot that lesson. HTH

[akrvr]

Thanks for your thoughts. Yes, it was fuel starvation because the problem went away with the new electric fuel pump and returned when the new electric fuel pump went bad. I will remove the mechanical pump and check the arm on it.
BTW, the electric fuel pump is between the selector valve and the mechanical pump i.e. it pushes fuel through the mechanical pump.


Answers:
1, Theoretically no, but I would bypass it just to eliminate the possibility of a ruptured diaphragm filling the crankcase with fuel.
2. Bad cam lobe would do it, but highly unlikely considering the force exerted by the pump on the lobe compared to the valve train. If the hand prime works and the engine spinning doesn't, I'd suspect the arm on the pump has either bent from being weak or bent because of a crack in the arm. I've seen this a number of times in my 43 years of being a mechanic. (BTW I have seen 1 bad cam lobe in that same time frame) Since the engine actuating arm and the hand priming lever are operating the same diaphragm and valving, you've eliminated everything in the pump except the arm (and it's pivot) that extends into the engine.
As an aside, are you sure your sputtering under load is due to lack of fuel? One way to be sure is to use a propane torch with a hose on it, tape the open end of the hose over the carb throat, when it starts to sputter, turn on the propane, if the problem goes away or significantly improves, I'd be looking elsewhere for a problem. The reason I bring this up is that a bad condenser in the ignition will give those exact symptoms. Fooled me a once a long time ago (3 fuel pumps and 2 carbs later) never forgot that lesson. HTH

[Sputnicker]

I'm having similar problems. Just finished a complete mechanical restoration and installed a brand new aftermarket mechanical fuel pump (AC copy with no manufacturer name on it). New camshaft, new tanks, new lines, rebuilt carb, Pertronix distributor, new wiring, etc. The new engine ran perfectly until the pump stopped pumping at 217 miles. Thought it might be vapor lock, so I undid the line from the carb and no amount of cranking or manual operation produced any fuel. Switched tanks, no difference. Disassembled the pump and couldn't see anything wrong. Reassembled reinstalled and it worked for a while, but quit again. Got an identical replacement and it worked for the duration of a one-hour test drive, but then I couldn't restart after a half hour of sitting/heat soaking. Actually, it started briefly, but quit after a few seconds when the float bowl was empty (educated guess).

I never had any problem with the original pump - even in the summer in Arizona. Would have rebuilt it , but the kit I got was the wrong one - and its 50 years old. Decided to install a NAPA electric pump (the small Facet Posi-Flo suggested by Teri Ann) between the selector valve and the mechanical pump. I'll let you know how it works.

I suspect the aftermarket mechanical pumps are not quite the same as the original AC (even though they look exactly the same), but I've changed so many other things that I can't be positive at this point. For example, the plumbing to the pump is probably more restricted with the selector valve, which is new, and more circuitous plumbing.

[kevkon]

Seems like there are an awful lot of posts relating to fuel supply issues. Given the nature of a Series truck and the relatively low fuel consumption coupled with a relatively high tank, I certainly wouldn't expect so many problems. I'm wondering if this is not a compatibility issue with the newer pump diaphragms and the increase of ethanol in current fuels. I wonder if the older oem pump diaphragms had a slightly different composition that was slightly more compatible with the newer fuels? Or is just that this is another Chinese junk issue? I certainly know from experience that any aftermarket parts available today can be enormously inconsistent in quality.

[TedW]

Full post under What-Did-You-Do-To-Your-Rover-Today, with pics.

Very beefy unit.

[gudjeon]

Howdy Kevkon,

I had a few new pumps not work out of the box. I don't think it is a matter of fuel composition because they won't work from the start. If working for some time, materials could be tested for compatibility.

Bolting on such crap sent a chill down my spine. I did not want to rely on this stuff when I am miles into the boonies. Trip down to Napa solved all my problems.:thumb-up:

[akrvr]

Does anyone have a pump that failed but still works when you use the hand prime lever?

[SeriesShorty]

I replaced my mechanical as a matter of course when I first got my 66IIa ex-MoD. Same issue, no workie. It worked just fine as long as I sat there and pumped the lever by hand. After fighting with it 2 days in a row and wasting time I installed an electric pump and bypassed the mechanical altogether. I also bypassed the tank switchover valve since I'm only using one tank. I couldn't be happier with the electric pump. :thumb-up:

[Sputnicker]

Update. Installed the Facet Posi-Flo electric pump (lower pressure version) from NAPA and everything is working perfectly at 100+ temperatures. I currently have it routed in series through the mechanical pump, but may re-route directly to the carb once it survives the infant mortality phase. I like the idea of redundant pumps, but the possibility of filling the crankcase with gasoline through a failed diaphragm gives me pause.

[cetesse]

Hi,
Where did you mount the electric pump? I have a 109?

Also, how did you wire the pump? Add any fuses?

Sincerely,
Chris




I replaced my mechanical as a matter of course when I first got my 66IIa ex-MoD. Same issue, no workie. It worked just fine as long as I sat there and pumped the lever by hand. After fighting with it 2 days in a row and wasting time I installed an electric pump and bypassed the mechanical altogether. I also bypassed the tank switchover valve since I'm only using one tank. I couldn't be happier with the electric pump. :thumb-up: