Need 753 Fuel Pump Help

[Walleye Guy 22]

I previously posted a few fuel pump questions here (see link below) but it's been quite a few months so I thought I'd create a new post.

 

Quick update: my dad bought an NOS Kohler fuel pump for his 1963 753 but can't seem to get it to pump fuel.

 

He's a retired mechanic (81 years old) and is very familiar with carburetors, fuel pumps, etc but he's not good with the internet so he asked me to post this for him.

 

He says this pump is a vacuum pump but he can't get it to pump any fuel, so he asked me to post these two questions on this sight:

 

1. How does the vacuum pump actually deliver fuel? 
2. Is there an eccentric on the cam that drives it?  If not, then what actually actuates the fuel pump?

 

Thanks in advance for any help and/or suggestions.  My great-grandfather bought this tractor new and my dad is trying to get it running again.

 

Thanks to all of you he's getting very close!

 

 

[pfrederi 17,738]

A vacuum pump uses the changing pressure  in the crankcase to move a diaphragm  the other side of the diaphragm moves the gas.

Edited January 12, 2023 by pfrederi

[peter lena 8,622]

@Walleye Guy   https://www.zoro.com/super-lube-4-oz-hydraulic-oil-bottle-150-iso-viscosity-85w-sae-51004/i/G5124506/?    recommend this  to lubricate all your cables , and related linkage / lever points , also let the cabling show you where it wants to be , don,t force or jam it in place , with lubrication in it , check its slide function as you go , shis simple detailing  assures a n easy  choke / throttle control .  that super lube oil is at your local h/w store . would hang  new cables vertically  and get the lube to drip top to bottom out , to insure  coverage , add  cable clips  ,  should be  smooth / easy , pete  

[Walleye Guy 22]

He lives two hours away, but I'm driving down there this weekend to help him with a few projects including this one. 

 

Do you have any idea why the pump doesn't appear to be working?

 

Can you give me a few things to check?

[Blasterdad 2,692]

59 minutes ago, Walleye Guy said:

He says this pump is a vacuum pump but he can't get it to pump any fuel

That's not a vacuum pump, hoses backwards maybe ?

I "prime" my fuel pumps by blowing air into the tank.

Unhook fuel line at the carb, blow air into the tank, gas should come out the hose.

If it is a NOS pump for a K181, inlet for the pump should be on the left facing it from the front.

Edited January 12, 2023 by Blasterdad

[Pullstart 62,846]

Yep, make sure it’s hooked up correctly and that fuel flows without it.

 

My 502 has no fuel pump.  It’ll run out of fuel in the tank before it stalls from starvation.

[Walleye Guy 22]

The pump P/N is B-231390-S and it's NOS.  That's what the documentation said this tractor required.  

This weekend I'll check the fuel flow as described above by Blasterdad.

Thank-you for these suggestions.

pfrederi. my dad wondered if there was supposed to be an eccentric that would actuate the pump.  I'll tell him that it's actuated by crankcase pressure.

Please feel free to continue to give us things to check.  

Thank-you!

 

[Blasterdad 2,692]

1 minute ago, Walleye Guy said:

  I'll tell him that it's actuated by crankcase pressure.

No, don't tell him that, it's not a vacuum pump, it has a cam & lever....

[Blasterdad 2,692]

Once the pump is primed as I described, take the sparkplug out & crank over the engine.

Gas should "pump" (pulse) out of the hose. Helps if you have a cup to catch it in... No smoking or heaters nearby!!!

[Ed Kennell 38,163]

14 minutes ago, Walleye Guy said:

The pump P/N is B-231390-S and it's NOS.

this is a pulse pump, but to the best of my knowledge, the 7HP Kohler uses a mechanical lever type fuel pump that is activated by a cam.

[Blasterdad 2,692]

9 minutes ago, Ed Kennell said:

this is a pulse pump, but to the best of my knowledge, the 7HP Kohler uses a mechanical lever type fuel pump that is activated by a cam.

I didn't look up the part #. Good catch, I was looking at the pics in his other thread...

[Walleye Guy 22]

I have not seen the pump myself.  What is the consensus among the experts?  Is it a vacuum pump, mechanical pump or pulse pump?  Dad told me something (I'm paraphrasing here) about there is a cam in the engine but it's off to the side and doesn't look like it lines up with the pump.  As I type this, I'm not sure what happened to the original pump that we could use for comparison.  It's probably gone.

[Ed Kennell 38,163]

Kohler “NOS” Pump OEM: B-231390-S | eBay

 

This pump does not have a lever, so it is a pulse pump that is activated by the alternating (pulsing) pressure/vacuum in the crankcase.

IAgain, I do not think the 1963 7HP Kohlers used a pulse pump.

[Walleye Guy 22]

Ed, thank you for that Ebay link.  I don't know the details (and I can verify this weekend) but when we looked in the parts diagram (which were supposed to be for this tractor) the B-231390-S was spec'd so that is what we ordered.  I need to double check the paperwork that was referenced because maybe we had the wrong diagrams.  Do you have another P/N for what you think is the correct fuel pump?  Do you happen to have the correct parts diagram?  The serial number of the tractor is 62-22277.

[Ed Kennell 38,163]

@gwest_ca    Garry, can you please post this for him?

[pfrederi 17,738]

 First off.  if your engine is original  Spec# 28626 Then it looks like it did come with a vacuum pump  (see C2 in the parts picture no arm) 

 

One issue here is 7-8 hp kohlers used a different mechanical pump than the big  block 10hp and up.  If you are trying to run a mechanical pump you need the one on the left with offset actuating arm. (pic 2)

 

 

[Ed Kennell 38,163]

Thanks Paul. I was not aware pulse pumps were used back then.     So,  You may have the correct pump. Make sure the pump is installed with the arrow pointing to the carb. and there is a good flow of fuel to the pump, then crank the engine and check for a good spurting of fuel from the pump outlet.     For the pump to work,  the crankcase must be sealed to create the pulse.  If the pump does not work, remove the oil fill plug and see if you can feel a good pulse while cranking the engine.    

Bad valve stem seals, piston rings, or a bad breather check valve could possibly cause a low pulse.

If you do have to go to a mechanical pump. make sure the pump arm is under the cam.

[Pullstart 62,846]

I believe that the engine makes a pulse, regardless of whether it came with a lever style or not.  A pulse will work 

[rmaynard 15,448]

My 701 with a K161 engines had a lever style pump and I replaced it with a pulse type pump. Either will work. But to the best of my knowledge, all of the cams in K161's have a lobe for a lever.

[Lane Ranger 10,968]

This was a very good thread on the various features of the old fuel pumps.  
 

 

I would also mention the mechanical ones at this time use to have the priming level on the side of the pump which was a very nice feature for starting the motor easily! 
 

We kept o drawer of the old metal fuel pumps as we often rebuilt or stole parts from the old fuel pumps

 

Edited January 13, 2023 by Lane Ranger

[squonk 41,096]

64 704 had pulse no lever pump. I think Bob is correct on the cam. I also think the only differences in the small block cams were spark advance and compression release.

Edited January 13, 2023 by squonk

[Walleye Guy 22]

 

Thank-you all for this information, you guys are great.  Attached is a picture of the engine ID tag...it is a 28626E.  I don't think the engine was ever replaced so it should be original.  I believe what I was trying to say earlier is that dad said there is a lobe on the cam but it appears to be off to the side.  I'll verify that this weekend.  Based on what is posted above, it sounds like if the engine is too tired to make the pulse for the vacuum pump then we could switch to the level style.  Is that true?  We'll do some troubleshooting this weekend to see if we can learn anything.  pfrederi, do you have the P/N's of those two lever actuated pumps?  Is it true that the cam would have the lobe for the mechanical pump even though it was built with a vacuum pump?  In terms of manufacturing and using common parts, this makes sense to me for them to have one cam for both style engines.  rmaynard, what was the reason you switched from a mechanical pump to a pulse pump?  Is one more ideal than the other?  Lane Ranger said the mechanical style has a priming feature.  PS: I'll be away from email this morning from around 9 am - 1 pm eastern.  I'll check back then for responses.  Thank-you again to everyone.

[Ed Kennell 38,163]

https://www.bing.com/videos/search?q=how+much+pulse+is+needed+for+a+pulse+fuel+pump&&view=detail&mid=FA4E327E89A65F1FBEB0FA4E327E89A65F1FBEB0&&FORM=VRDGAR&ru=%2Fvideos%2Fsearch%3Fq%3Dhow%20much%20pulse%20is%20needed%20for%20a%20pulse%20fuel%20pump%26%26FORM%3DVDVVXX

 

It's a different style,pump but a good video of how a pulse pump works and some reasons why they may not work..

[Pullstart 62,846]

24 minutes ago, Walleye Guy said:

Lane Ranger said the mechanical style has a priming feature. 

Not all of them did, just some of the old ones.  It was a spring arm on the side of the pump, very evident.  I’ve never seen a new one like that.

[pfrederi 17,738]

1 hour ago, Walleye Guy said:

 

Thank-you all for this information, you guys are great.  Attached is a picture of the engine ID tag...it is a 28626E.  I don't think the engine was ever replaced so it should be original.  I believe what I was trying to say earlier is that dad said there is a lobe on the cam but it appears to be off to the side.  I'll verify that this weekend.  Based on what is posted above, it sounds like if the engine is too tired to make the pulse for the vacuum pump then we could switch to the level style.  Is that true?  We'll do some troubleshooting this weekend to see if we can learn anything.  pfrederi, do you have the P/N's of those two lever actuated pumps?  Is it true that the cam would have the lobe for the mechanical pump even though it was built with a vacuum pump?  In terms of manufacturing and using common parts, this makes sense to me for them to have one cam for both style engines.  rmaynard, what was the reason you switched from a mechanical pump to a pulse pump?  Is one more ideal than the other?  Lane Ranger said the mechanical style has a priming feature.  PS: I'll be away from email this morning from around 9 am - 1 pm eastern.  I'll check back then for responses.  Thank-you again to everyone.

 

 

 

That is why the arm on the small block pump has the offset