Fuel pump question

[moe1965 753]

I'm working on a  K 181 which has a vacume style fuel pump.   I'm not sure if fuel is getting by the seals and getting into the engine.  Is there a way to test this I thought about just rebuilding it but why kick a sleeping dog and I'm not to keen on the quality of replacement anything any more.   

[WHX?? 51,702]

You can plug the outlet and blow into the inlet. If air escapes the diaphragm is ruptured. Wouldn't hurt to disassemble and inspect. I would replace the diaphragm. I believe Buckrancher and Bob Maynard has them. 

[ebinmaine 72,426]

34 minutes ago, WHX?? said:

You can plug the outlet and blow into the inlet. If air escapes the diaphragm is ruptured. Wouldn't hurt to disassemble and inspect. I would replace the diaphragm. I believe Buckrancher and Bob Maynard has them. 

 

seconded. 

[RED-Z06 2,567]

I pull the pulse feed while idling..if theres fuel in the pulse line the pump diaphragm is compromised 

[ri702bill 9,348]

13 minutes ago, RED-Z06 said:

I pull the pulse feed while idling..if theres fuel in the pulse line the pump diaphragm is compromised 

Reminds me of an old faulty GM Turbo 400 AT Modulator Valve check - if there was ATF in the line, the valve was bad. (A bad one would allow the engine to suck almost all the tranny fluid out!!)

[WHX?? 51,702]

7 hours ago, RED-Z06 said:

I pull the pulse feed while idling..if theres fuel in the pulse line the pump diaphragm is compromised 

No can do Red ... the pump is bolted to the block and recieves it pulses directly so ther is no pulse line. 

 

One of these days went EB is not retired and has the time to doing an instructional of rebuilding them he will do so. I'll help you out EB I have all the pics... 

Edited January 27, 2024 by WHX??

[RED-Z06 2,567]

36 minutes ago, WHX?? said:

No can do Red ... the pump is bolted to the block and recieves it pulses directly so ther is no pulse line. 

 

One of these days went EB is not retired and has the time to doing an instructional of rebuilding them he will do so. I'll help you out EB I have all the pics... 

Why would they use a pulse pump vs mechanical?

[RED-Z06 2,567]

So we're all on the same page, K181 has a port below the carb on the front of the block, for a mechanical pump that rides on the cam...

 

A pulse pump operates on crankcase or intake manifold pulses via a hose/fitting or tapping into the case near the top of the crankcase.

 

Which one are we talking about here, both can push fuel into the oil.

[ebinmaine 72,426]

24 minutes ago, RED-Z06 said:

Why would they use a pulse pump vs mechanical?

WHY is always a interesting question. 

Likely it was a matter of available parts and technology back then. 

 

My experience shows me that the pulse type pump on a Kohler K-series works just fine.  

 

 

The diaphragm in a pulse type Kohler pump is easier to replace.  

 

 

[ebinmaine 72,426]

20 minutes ago, RED-Z06 said:

So we're all on the same page, K181 has a port below the carb on the front of the block, for a mechanical pump that rides on the cam

 

OR...

A pulse type pump

 

 

 

[RED-Z06 2,567]

Just now, ebinmaine said:

 

OR...

A pulse type pump

 

 

 

Its not the same, the name is based on how its driven, pulse type driven by air pulses, or mechanical, driven by a lever.  A solenoid style electric, mechanical, and air pulse..all deliver fuel in pulses.

[Racinbob 11,919]

@RED-Z06 Apparently you haven't dealt with a pulse pump on a K series. Go back to Jims post #6. The pump on the right is a pulse style on the K's. The style you pictured is an aftermarket and also used on other engines. Making a plate to cover where the original pump mounts, drilling and tapping it for a hose fitting and you can use the style you pictured.

Edited January 27, 2024 by Racinbob

[RED-Z06 2,567]

4 minutes ago, Racinbob said:

@RED-Z06 Apparently you haven't dealt with a pulse pump on a K series. Go back to Jims post #6. The pump on the right is a pulse style on the K's. The style you pictured is an aftermarket and also used on other engines. Making a plate to cover where the original pump mounts, drilling and tapping it for a hose fitting and you can use the style you pictured.

That's why i asked, given the same mounting point, same physical size, why would they opt for 2 separate drive styles (air pulse vs mechanical).

[ebinmaine 72,426]

21 minutes ago, RED-Z06 said:

Its not the same, the name is based on how its driven, pulse type driven by air pulses, or mechanical, driven by a lever.  A solenoid style electric, mechanical, and air pulse..all deliver fuel in pulses.

Oh I know it's not the same. 

We have them both here.  

Mid 60s 8 HP Kohlers can have either one.  

I'm talking about the mounting location.  

 

47 minutes ago, RED-Z06 said:

K181 has a port below the carb on the front of the block

 

Which may have a mechanical pump...

OR 

A pulse type pump. 

 

I write "OR" because I'm not sure if the pumps are interchangeable with one another.  

 

[ebinmaine 72,426]

Just now, RED-Z06 said:

That's why i asked, given the same mounting point, same physical size, why would they opt for 2 separate drive styles (air pulse vs mechanical).

The "why" of every manufacturer is only a guess some 55 years later.  

 

My guess...

Post # 9. 

[RED-Z06 2,567]

6 minutes ago, ebinmaine said:

Oh I know it's not the same. 

We have them both here.  

Mid 60s 8 HP Kohlers can have either one.  

I'm talking about the mounting location.  

 

 

Which may have a mechanical pump...

OR 

A pulse type pump. 

 

I write "OR" because I'm not sure if the pumps are interchangeable with one another.  

 

I wonder if the cam has the drive lobe on the air pulse style or if they used a completely different cam?

[ebinmaine 72,426]

44 minutes ago, RED-Z06 said:

I wonder if the cam has the drive lobe on the air pulse style or if they used a completely different cam?

 

I've wondered that myself.  

[JoeM 8,293]

As of now, any diaphragm pumps that go bad get electric-fied.

Unless your looking for authenticity, electric pumps are the way to go.

Easier starting, no fuel in the oil, pumps at all rpm, etc. And the cost is not much more than a good mechanical rebuild kit. 

 

[Handy Don 13,980]

14 hours ago, RED-Z06 said:

So we're all on the same page, K181 has a port below the carb on the front of the block, for a mechanical pump that rides on the cam...

As shown below, same port on the K181 engine has been used by BOTH cam/lever driven and pulse-only pumps. Several threads here have caught this.

One might think that with a well-functioning breather that there wouldn’t be enough crankcase pressure change to make this work, but when you look a the area of the diaphragm and the very small amount of movement needed to pump adequate fuel for each combustion cycle, it is clear that it can (and does) work. Of course, this probably requires a tank above or very near the pump level but this was true of most WH’s and, I suspect, ALL of those that used K181s.

 

14 hours ago, WHX?? said: