United Technologies pump

[1wonton]

My '61 B model Mack (237 engine) has a United Technologies diesel pump, it seems to be governed at about 1500 rpm, can't get any higher than that.  How can I adjust the governor to allow higher engine speed?

[BOBWhite]

Do you have a picture of the engine tag? Some models of engine were governed at reduced speed for fuel efficiency. Check the engine tag to see if it's one of those engines. I'm not sure about how to increase the speed but id be very weary of messing with the injection pumps on Mack engines. 

[Hans Remmers]

I wonder if those ever came with a dual speed governor. I have a 285 with an ambac that's got a dual speed and we just supplied it with constant air pressure to run at the higher speed.

[1wonton]

Here's a picture of the tag on the pump; looks like is says VB / C6393A (hard to read).

[doubleclutchinweasel]

On 5/27/2023 at 7:51 PM, BOBWhite said:

Do you have a picture of the engine tag? Some models of engine were governed at reduced speed for fuel efficiency. Check the engine tag to see if it's one of those engines. I'm not sure about how to increase the speed but id be very weary of messing with the injection pumps on Mack engines. 

Wasn't that the ENDT-675R that was governed at something like 1,800 RPM?  

[doubleclutchinweasel]

On 5/28/2023 at 9:13 AM, 1wonton said:

Here's a picture of the tag on the pump; looks like is says VB / C6393A (hard to read).

Can you get a picture of the engine tag as well?

[BOBWhite]

1 hour ago, doubleclutchinweasel said:

Wasn't that the ENDT-675R that was governed at something like 1,800 RPM?  

Here is a chart of the later R reduced speed engine's so I would think it would be something similar:

I'm not sure what year they came out with the Reduced speed engines but 61 seems too early. Im thinking it could be something in the governor that's stopping the rack from going to full or maybe the shut off cable isn't adjusted right or isn't releasing all the way. Much speculation 

[doubleclutchinweasel]

If it's a 237, it probably isn't a '61 engine.

I think you are right.  Sounds like something in the governor.

[terry]

Could that be a rebuilders tag?   terry

Edited May 31, 2023 by terry

[1wonton]

The engine is a 673C, 250 hp; should I leave the governor alone?

[doubleclutchinweasel]

2 hours ago, 1wonton said:

The engine is a 673C, 250 hp; should I leave the governor alone?

That engine should NOT be governed at that RPM.  It should turn up to 2,100 or so.  There is definitely something amiss there.  I'm sure one of the gurus here will be able to help.

And, again, I sure miss Glenn.  He could tell you in half a heartbeat what it needed.

[1wonton]

Thanks Weasel, would you know how to do this?

[doubleclutchinweasel]

I'm not your best resource!  Lots more qualified guys on here.  I do have a service manual around here that might have some procedures in it.  I will look and see if I can find you some info.

[doubleclutchinweasel]

I found the fuel pump section in my book. If I knew which pump you have, I’d be glad to post some pictures of the appropriate pages. 
APE.  PSJ. PSM.  CAV.  
there is a high speed adjustment screw on some of them. 
 

[doubleclutchinweasel]

Mine was the APE style, if that helps.