Need help with mechanical fuel pump

[Permpaul 10]

I'm a mechanic in the marine corps and have been working on cars since I was 14 and I'm working on a 1969 mustang coupe right now, and I installed a new mechanical fuel pump, like I have done a number of times before but for some reason I can not get this one to work, I double and triple checked the hoses, and I'm just getting no fuel to the carb... Any ideas on what's up?

[LoneWolf2U 136]

If you didn't match up the new to the old pump, the new may have a shorter arm and not riding the cam excentric. Or the ex came loose from the cam causing the no pump problem. Check the Lenght and cam first.

[Print Dad 58]

Hello Permpaul,

FIRST - -Thanks for your service to our country.

Always great to hear from our millitay people.

 

I know you have experience in wrenching BUt

it is possible to put the pump in with the arm BELOW the eccentric?

 

The arm is supposed to ride on top of the eccentric. The only way to

tell is to pull the pump and re-install making sure the arm is pointing upward

as you install so that it goes on the top of the ecentric.

 

If you are pulling the PUMP again - -(may have to) you could pump

the arm by hand and see if you feel pressure on the outlet side.

 

double check the fuel lines to be sure you are using Inlet as in.

 

lastly - it is possible you have gotten a BAD pump. Quality control

is NOT too good these days.

 

Hope this helps and BE SAFE

 

Print Dad

[Print Dad 58]

Hello Permpaul,

FIRST - -Thanks for your service to our country.

Always great to hear from our millitay people.

 

I know you have experience in wrenching BUt

it is possible to put the pump in with the arm BELOW the eccentric?

 

The arm is supposed to ride on top of the eccentric. The only way to

tell is to pull the pump and re-install making sure the arm is pointing upward

as you install so that it goes on the top of the ecentric.

 

If you are pulling the PUMP again - -(may have to) you could pump

the arm by hand and see if you feel pressure on the outlet side.

 

double check the fuel lines to be sure you are using Inlet as in.

 

lastly - it is possible you have gotten a BAD pump. Quality control

is NOT too good these days.

 

Hope this helps and BE SAFE

 

Print Dad

[buening 63]

I believe the arm rests below the eccentric and the eccentric action pumps the arm downwards. When I had mine out a few months ago. I had to stick it be sure to aim the arm down at an angle, hold the pump body and push/rotate down to get the mounting face of the pump body flush with the timing cover.

[buening 63]

I believe the arm rests below the eccentric and the eccentric action pumps the arm downwards. When I had mine out a few months ago. I had to stick it be sure to aim the arm down at an angle, hold the pump body and push/rotate down to get the mounting face of the pump body flush with the timing cover.

[Print Dad 58]

Hello All,

Once again I find that I posted incorrect info.

The arm is supposed to fit UNDER the eccentric.

Nice catch buening and of course you are right about

this.

 

Pernpaul - - you should not have to worry about the position

of the arm if the motor is in the correct position.

What I mean is - -after you pull the OLD pump out and

clean the mounting surface - -just place the new pump

in the opening - - -if the NEW PUMP does not sit flush

with the Housing cover, then pull the pump out, rotate

the motor and try to re-install. See if it sits flush at that

point. It should.

The eccenric is an egg shaped circle that will push DOWN

on the arm at the proper time.

Sometimes the arm is hitting the arm in a downward position

and that requires you to pull the fuel pump in (because) the

eccentric is trying to get the pump in the proper position.

 

To eliminate any guess work - - see if the pump sits FLUSH

to the motor by hand. If it does - - install the bolts and you are

good to go.

 

Sorry about the error - -I think sometimes the old brain freezes.

I WILL be more carefull in the future

 

Print Dad

[Print Dad 58]

Hello All,

Once again I find that I posted incorrect info.

The arm is supposed to fit UNDER the eccentric.

Nice catch buening and of course you are right about

this.

 

Pernpaul - - you should not have to worry about the position

of the arm if the motor is in the correct position.

What I mean is - -after you pull the OLD pump out and

clean the mounting surface - -just place the new pump

in the opening - - -if the NEW PUMP does not sit flush

with the Housing cover, then pull the pump out, rotate

the motor and try to re-install. See if it sits flush at that

point. It should.

The eccenric is an egg shaped circle that will push DOWN

on the arm at the proper time.

Sometimes the arm is hitting the arm in a downward position

and that requires you to pull the fuel pump in (because) the

eccentric is trying to get the pump in the proper position.

 

To eliminate any guess work - - see if the pump sits FLUSH

to the motor by hand. If it does - - install the bolts and you are

good to go.

 

Sorry about the error - -I think sometimes the old brain freezes.

I WILL be more carefull in the future

 

Print Dad

[1969vert 55]

Make sure there is a fuel pump cam in there..some people leave them out for all electric pumps..also blow the fuel line back to the tank the sock could have some pluggage on it in the tank..

[1969vert 55]

Make sure there is a fuel pump cam in there..some people leave them out for all electric pumps..also blow the fuel line back to the tank the sock could have some pluggage on it in the tank..

[Tgriffin91 27]

My 2 cents.

Did the old pump work?

Try cranking the motor with the line to the carb disconnected and see if fuel comes out. Then you'll know if your pump is working.

It could also be a small crack or hole in the fuel line somewhere. These are hard to find but can also cause this problem.

Could be that the carb is gummed up.

Or a bad pump as stated before.

Good luck and let us know what ou find.

[Tgriffin91 27]

My 2 cents.

Did the old pump work?

Try cranking the motor with the line to the carb disconnected and see if fuel comes out. Then you'll know if your pump is working.

It could also be a small crack or hole in the fuel line somewhere. These are hard to find but can also cause this problem.

Could be that the carb is gummed up.

Or a bad pump as stated before.

Good luck and let us know what ou find.

[Max Power 74]

Most people who have this problem hooked the fuel lines up backwards.

[Max Power 74]

Most people who have this problem hooked the fuel lines up backwards.

[Permpaul 10]

Thank you for everyone's input, the old pump did work but it was electric, and as far as the lines being hooked up backwards I thought of that and tried them both ways, I haven't actually gotten a chance to work on it again since I posted this as we have been working 18 hour days, but I'm going to get back at it first thing tomorrow and try to use all of your suggestions to make it work. Thanks again and if I have anymore questions I know where to go.

[Permpaul 10]

Thank you for everyone's input, the old pump did work but it was electric, and as far as the lines being hooked up backwards I thought of that and tried them both ways, I haven't actually gotten a chance to work on it again since I posted this as we have been working 18 hour days, but I'm going to get back at it first thing tomorrow and try to use all of your suggestions to make it work. Thanks again and if I have anymore questions I know where to go.

[j69302 11]

If it previously had electric, there is a chance the fuel pump eccentric isnt even installed.

 

Get a flashlight and mirror, look into the hole where the pump mounts. You should see a circular cup, mounted to the front of the camshaft gear. This gear is mounted off-center and acts as a cam to move the lever on the pump.

 

Worse case, you might have to pull the timing cover if you can't get a good look with the mirror, or feel for it while installing the pump.

[j69302 11]

If it previously had electric, there is a chance the fuel pump eccentric isnt even installed.

 

Get a flashlight and mirror, look into the hole where the pump mounts. You should see a circular cup, mounted to the front of the camshaft gear. This gear is mounted off-center and acts as a cam to move the lever on the pump.

 

Worse case, you might have to pull the timing cover if you can't get a good look with the mirror, or feel for it while installing the pump.

[FrozenMonkey 12]

I was going to go from electric to mechanical a few months ago but from the advice I got on this board I checked for the eccentric. For some reason whoever installed the cam didn't put the eccentric back on. Saved me a ton of hassle and just went with another electric. Sure hate the noise they make though.

[FrozenMonkey 12]

I was going to go from electric to mechanical a few months ago but from the advice I got on this board I checked for the eccentric. For some reason whoever installed the cam didn't put the eccentric back on. Saved me a ton of hassle and just went with another electric. Sure hate the noise they make though.

[miketyler 15]

That's a coincidence. I am having same issue. My engine is 351c and today would not pickup a prime from the tank or from a hose submerged in a container of gas.

 

In the vise, the pump feels like its sucking on both ports. Diaphragm is tight, if I compress and hold both ports closed, the pump stays closed. To be certain, the hose nipple side is the input side and the female side with the inverted flair is the carb side, right?

Edited June 24, 2013 by miketyler

[miketyler 15]

That's a coincidence. I am having same issue. My engine is 351c and today would not pickup a prime from the tank or from a hose submerged in a container of gas.

 

In the vise, the pump feels like its sucking on both ports. Diaphragm is tight, if I compress and hold both ports closed, the pump stays closed. To be certain, the hose nipple side is the input side and the female side with the inverted flair is the carb side, right?

Edited June 24, 2013 by miketyler

[Wycked69 20]

That's a coincidence. I am having same issue. My engine is 351c and today would not pickup a prime from the tank or from a hose submerged in a container of gas.

 

In the vise, the pump feels like its sucking on both ports. Diaphragm is tight, if I compress and hold both ports closed, the pump stays closed. To be certain, the hose nipple side is the input side and the fe mail with the inverted flair is the carb side, right?

 

I had a similar problem when I rebuilt a 351C and also installed a new gas tank and fuel line. I Could not draw fuel up from the tank through the line. I removed the end of the "flexline" from the fuel pump and put the end of the fuel line hose into a 2-liter bottle. I then placed a simple air nozzle on a compressed airline, wrapped a shop rag around it, and placed in the fuel neck opening of the gas tank and with a cupped hand (to seal the opening) I applied a little air pressure to the tank. Fuel came out of the flex line into the 2 liter bottle. I used a small set of vise grips to pinch off the flex line to stop the fuel till I reinstalled the flex line (hose) end on to the fuel pump. It then pumped fuel to the carb with no problem.

 

I could only assume the pump did not have enough a$$ to draw the fuel up through the new line and thought a little assistance by "priming" the fuel line would help. Fixed my issue

[Wycked69 20]

That's a coincidence. I am having same issue. My engine is 351c and today would not pickup a prime from the tank or from a hose submerged in a container of gas.

 

In the vise, the pump feels like its sucking on both ports. Diaphragm is tight, if I compress and hold both ports closed, the pump stays closed. To be certain, the hose nipple side is the input side and the fe mail with the inverted flair is the carb side, right?

 

I had a similar problem when I rebuilt a 351C and also installed a new gas tank and fuel line. I Could not draw fuel up from the tank through the line. I removed the end of the "flexline" from the fuel pump and put the end of the fuel line hose into a 2-liter bottle. I then placed a simple air nozzle on a compressed airline, wrapped a shop rag around it, and placed in the fuel neck opening of the gas tank and with a cupped hand (to seal the opening) I applied a little air pressure to the tank. Fuel came out of the flex line into the 2 liter bottle. I used a small set of vise grips to pinch off the flex line to stop the fuel till I reinstalled the flex line (hose) end on to the fuel pump. It then pumped fuel to the carb with no problem.

 

I could only assume the pump did not have enough a$$ to draw the fuel up through the new line and thought a little assistance by "priming" the fuel line would help. Fixed my issue