Engine/Transmission (1994 - 1998) Changed delivery valves, ???

[Matthug]

I swapped out my 131's for a set of 181's with less than 100K on them. My 131's here have 250K on them. Now I'm expecting more smoke and more power, but I have the exact opposite. The truck runs and idles smoother now, but I have less smoke and no noticeable extra power in fact if anything there's less power. My question is can the stock 131's be worn out to the point of actually dumping more fuel than 181's? The truck runs smoother now but I am definitely dissatisfied. Still a good bit of smoke but less than before. The truck is still fast don't get me wrong, I beat an RX-8 on the highway yesterday.

I'm going hook up a fuel pressure gauge real soon to check on that, I don't think it's an issue though. I have a brand new lift pump and overflow valve from PDR ready to go in if anything is amiss as far as fuel pressure but since I have no lack of power I didn't think that was it.

 

[Matthug]

Just an update, tonight it felt REALLY strong. Boost is up to 37 PSI whereas it was at 35 before so that means more fuel obviously. My seat of the pants is pretty good I guess because I noticed it felt stronger and then I looked at the gauge on one WOT run and boost was up 2 more PSI. I'm not sure what exactly happened, did things need time to seat in or something??? This is just weird.

One other thing, on several sites I looked at in the tech section about delivery valve swaps they say ''some older 160 pumps have copper O rings but they will not be reused''. Well I have an older 175 pump and it had copper O-rings, but I did not re-use them with the 181's I put in. No fuel leaks or anything. Still stumped.

 

[Cummins4Life]

Weird



I went from 131's to 181's to 191's then back to 131's. I could definately tell a difference when I went back. The 181's did smoke more than the stockers, but it wasnt a crazy amount. The 191's with 370's would stop traffic though. Sounds like you installed them correctly. Where you'll feel the DV's is in the lower midrange, not so much off idle but not so much wide open either. Roll into the throttle around 1300rpm and thats where you'll feel the difference. At least thats where I did.



Running 131's, 370's, HX40. WOT from a stop it would blow smoke and slowly start to spool the turbo until it lit. With 181's it would spool the turbo a good bit faster and chirp the tires into 2nd. With 191's it would light the turbo right quick and would roast the tires on the shift into 2nd.

 

[KHelfrich]

when you say you did not reuse the copper washers i ammume you mean you did not use any washers just the green o-rings and from what i understand weather or not you use the washers has nothing to do with which DV you use but with your pump cause where the DV sits in the pump is machined smoother on the newer pumps and thats why you dont need the crush washer



ken

 

[Matthug]

Yeah no washer anymore.

 

[Matthug]

Update- Hooked up my fuel pressure gauge today, 10 PSI at idle and 18 PSI at 2000 RPM. I changed out the overflow valve, 22 PSI at idle and 25-28 PSI at ~2000 RPM. THE BLACK SMOKE IS BACK and better than ever. Not too much gain up at WOT but partial throttle and upper RPM's feel much stronger. The truck runs even smoother than before and the low RPM light throttle shutter is gone. I'm glad it was just the overflow valve, I do have a spare lift pump if/when it goes out.