im having the same problem. only mine will get enough air to kill the engine and sometimes will get air in it after idling shuting it off and letting it sit. what size pick up and lines should i use?

 

For 90% of everyone here, 3/8" feed is plenty big.

 

So the with yours the pressure is fine at idle, but drops quickly under load too? I haven't had a chance to take a look at the truck today, but i think I'm going to cut off the old hardened end of the pickup line and clamp a fresh section to the fitting on the pump to try and get a better seal.

 

I don't have a psi guage but I've run 394 RWHP @ 3000+ RPMs on the dyno without any problems.

Bob

 

ok, an update... i checked for any leaks this morning and put a new section of suction line on before the pump, but no improvment. I put the old pump back on and everything is the same as before. 4spi at idle, slowly sucks it down to 0-1 psi at WOT in 4th and 5th at RMPs above 2400. Its got to be the pump? Cummins wont have another pump in until next week, but i want to run on the dyno this weekend. I just talked to napa and found a Carter inline pump rated at 10-14psi and 25 gph, is that any better than my stock pump?

 

Probably better than the stocker. The fact that you say the new pump drops very quickly and the old pump drops slowly tell me it's gotta be a bad pump for some reason. Probably pretty rare, But not outside the realm of possibility, I suppose.

 

I too am wondering about a carter lift pump.. They guys at Diesel pwr just put one on rust bucket.. seems pretty inexpensive compared to others.. I've also talked to a few buddies with 2nd gens and for mild hp applications they use them.. I've been thinking about also trying the new BD flow max pump, for the 24v.. Just have to wire it in.. it supposedly flows 10 psi all day long and comes with a 5 yr warrenty..

 

I think the Cummins pump is actually made by Carter. At least my stock replacment in my 91 (before the piston pump caught on) said "Carter" on it. Wroked just fine as far as I can tell. Cant remember my piston lift pump on my current truck.

 

http://www.go2marine.com/product.do?no=160837F

Just a thought! With all of the horror stories I hear about the 24 valves and their lift pumps killing their IP's, I will not run one on my Pile.
Justin

 

Finally got the replacement pump from cummins and found some time to bolt it on this weekend. Works perfectly! 12 psi at idle, 16 at 2000rpm, 15 at 3200. Under load the most i have seen it down to was abot 9psi at 2700 in 4th. These numbers sound more like what some of you are getting out of the low pressure piston pumps. Nothing bothers me more than new parts that are faulty

 

I'm guessing these #'s are in Neutral Free-revving ? sounds good

 

that would be correct, i guess i left out some details.