Cummins 4BT & Diesel Conversions Forums banner

1 - 9 of 9 Posts

·
Registered
Joined
·
322 Posts
Discussion Starter #1 (Edited)
Picked up a carter 3936316 piston lift pump on Epay. Was open box oem Cummins left over with a hole for the fuel to leak out instead of filling the crank case. Was having fueling issues with the ve 6bt. Read somewhere about using a fastenal spring to replace the one that comes in the pump. Ordered the spring and had it put in the pump and got it installed. Took care of the fueling issues. It's running 6.5 lbs and on a hard pull in hi gear it will drop to just about 3 lbs.
My question is since this is a high volume pump will the extra volume make up for the low side of the lift pump pressure? Also this pump has a 5/8 fitting one the supply end. This could justify the other torktech thread I started about fuel velocity??
We may find another heavier spring or try the one it came with as it doesn't feel that much tighter. Or a washer or two for more tension. I think it will be fine.
Side note the spring # is 110166720 from fastenal. I paid for 2 and got 4 so if anyone wants one if you cover the shipping it's yours.
Pump - 34 bucks-spacer-10-springs-16 so for 60 bucks and some line tweaking a low budget hvlp pump for the ve..
 

·
Premium Member
Joined
·
851 Posts
Would have to go back an check but that Fastenal spring may have been for the standard bore pump, if so it will have lower pressure when used in a hi-volume pump.

Cheers Steve
 

·
Selling 4bt & 6bt parts to all of N.America
Joined
·
330 Posts
So your aware, a Carter 3936316 is not a high volume pump. It is a 26mm piston pump. Yes, better than the diaphragm pump but not as good as the 30mm high volume pump I sell or THD sells. The 30mm piston pump is the one that is considered a high volume pump.

Keep an eye on your cheap Fastenal spring....my testing/findings of it back in the day was it is a weak spring & will lose it's spring rate fairly fast. I personally don't/won't use that spring for anything.
 

·
Registered
Joined
·
322 Posts
Discussion Starter #4 (Edited)
Good info. I will double check the bore but it sure looked like a larger bore. I have used the Delphi one and it's definitely larger than it.
Any feedback about the pressure drop/volume under a large load?
Also is there a spring available for about 10 lbs of pressure? On a tired ve am I concerned about nothing with the 15lb version everyone is talking about? I'd rather be in the 10 lb range as it is nearly double what it's got now and with higher volume than diaphragm pump..
 

·
Selling 4bt & 6bt parts to all of N.America
Joined
·
330 Posts
The #3936316 is an old model & 26mm....not a 30mm
Your pressure at idle & under WOT will continue to drop over time. As mentioned, keep an eye on your pressures, as you are already at the min for WOT.
 

·
Registered
Joined
·
322 Posts
Discussion Starter #6
Verified it is 26mm. Played with different springs. Found an old valve spring that fits pretty well and its 9.4 lbs. Climbs to 10 at higher rpm. Didn't load test it yet. Might be a briggs spring but definitely not a cheap fastenal lol.
I feel pretty good about using it as it is a superior pump compared to the diaphragm..
 

·
Selling 4bt & 6bt parts to all of N.America
Joined
·
330 Posts
Good call ditching that Fastenal spring !!!
 

·
Registered
Joined
·
10,631 Posts
Might try to identify that spring. Could be an item that other users could use. A Briggs powered Cummins. That makes sense. LOL.
 

·
Registered
Joined
·
322 Posts
Discussion Starter #9
Being a horder of old stuff my guess is as good as yours. Could be anywhere from a Datsun to briggs. Johnny Cash and I have built it one piece at a time except I can't figure out why it costs me so much money while it didn't cost him a dime!
 
1 - 9 of 9 Posts
Top