Cummins 5.9 12v update

[cgoodwin]

Last year I replaced my lift pump with a new one, there was nothing wrong with the old one but I had a new one in a box, was changing the starter and thought I might as well throw the new one on. One week later I could not run on VO, within 2 minutes of switching to VO I would lose power and have to switch to diesel. I checked the FPHE, valves, lines, tank, nothing was wrong. I bought another lift pump, installed it and had the same issue. Watching the fuel pressure I had 30 on diesel and minutes after switching it dropped to 0, switching back it took about a minute to establish fuel pressure again. I tried everything including a hose from the switching valve directly into a pan of heated virgin VO – same issue. I had been paying about $140 for lift pumps from NAPA and the same from a local parts house, both aftermarket. I happened to be near the Cummins dealer, stopped in and picked up a new lift pump from them ($90.00 my price) and installed it last week. I get 30psi on diesel and 30psi on VO.

In conclusion, do not buy aftermarket lift pumps for the 5.9 12v if you intend to run VO, there seems to be something about the temp of the fuel that affects the workings of the pump or its check valves, but they will not work on VO.

[soshea00@hotmail.com]

on the topic of fuel pumps for this truck, do you know of any wvo related issues that might cause the injection pump to weaken in a way that it would cause problems at idle with the A.C. on? I converted my truck prob a year and a half ago and it runs seamlessly, except with the A.C. on at idle. It started loping on veg. The lope gradually became more significant. Now on dino or veg, it lopes so hard that it cuts out. As soon as I put it in park, it idles great. As soon as I'm moving, its completely problem free. Yet, during idle, in drive, it lopes so bad that it cuts out. No normal mechanics have any idea why this might be, so I thought it might be grease related and you'd be the one to check with.
Thanks...and sorry if this is the wrong place.

[macattack_ga]

It will idle slower on wvo.
Have you upgraded the torque converter?
I have a similar issue, but it is because I now have a built transmission with a low stall torque converter.
I'll be bumping the idle up to see if that helps... You don't want to idle up too much because you'd have to stand on the brakes at a stop light/in traffic.