Cummins 5.9 12 valve mechanical expert

Ralph A Powell · 09-14-2022, 07:43 PM

Do you have a boost gauge? If the boost is down first thing to check is fuel filter. On one trip I drove all night with very low boost checked turbo hose for damage could find any thing. We stop for fuel in early am was looking at engine attendant come up and ask what we were doing told him about our problem with lack of boost. He told us to change filter luckily I alway card a couple. I changed it and were started out and instantly we had full boost.

rseibenick · 10-12-2022, 12:29 PM

Changed both filters . Both were black . Put a fuel pressure gauge on it . Took it out for a test. Cut them, open ad small black dots in the At 2000 had 28 PSI , when I got on it the pressure dropped to 15 . When I got off it cam e back up to 28. Now changing the overflow valve ,and see it that solves it. IF not, then the lift pump. Any other ideas. Thanks.

09-14-2022, 07:43 PM	#1
Ralph A Powell Member Join Date: Oct 2017 Location: Bay City Texas Posts: 387 Likes: 2 Liked 225 Times in 136 Posts	Re: Cummins 5.9 12 valve mechanical expert Do you have a boost gauge? If the boost is down first thing to check is fuel filter. On one trip I drove all night with very low boost checked turbo hose for damage could find any thing. We stop for fuel in early am was looking at engine attendant come up and ask what we were doing told him about our problem with lack of boost. He told us to change filter luckily I alway card a couple. I changed it and were started out and instantly we had full boost.

10-12-2022, 12:29 PM	#2
rseibenick Member Join Date: Dec 2002 Posts: 160 Likes: 24 Liked 20 Times in 7 Posts	Re: Cummins 5.9 12 valve mechanical expert Changed both filters . Both were black . Put a fuel pressure gauge on it . Took it out for a test. Cut them, open ad small black dots in the At 2000 had 28 PSI , when I got on it the pressure dropped to 15 . When I got off it cam e back up to 28. Now changing the overflow valve ,and see it that solves it. IF not, then the lift pump. Any other ideas. Thanks.