Ok so my buddy picks up a FB special, 03 dually, mostly stock besides a lift, with 280k miles down in FL last week. Then 2 days later, hooks up to his 5th wheel camper and heads to Ohio. Truck did great, until about the I95/I26 split in SC when it limped for Low Fuel Pressure. I've never been able to get an LB7 to limp on FP, but he's proved me wrong. lol..
Truck came with an Edge of same era, so he was able to at least read and clear the codes. I told him to monitor the FP, and change filter if it persisted. Never heard anything more, until next day when I get a call that truck made it home, but when he went out next morning, wouldn't start.. Pumped the primer, fires right up, dies in under 60.. I ask, did ya change filter? Nope, limped it on home he said. Popped low pressure a couple more time in mountains, but towed 12k lbs no problems. Humm.. Ok, lets grab a filter and toss it on.
While installing the filter I noticed someone had installed worm clamps on the filter head, and electrical taped all the fuel line they could reach. Troubling.. As anyone who's owned a diesel for a few days knows electrical tape and diesel fuel don't mix. But they were obviously chasing some rabbit, and covered all the bases.. Even put a hose with a bolt in it over the vac test port.. I can tell this is gonna get interesting. So stick around..
I found an old LBZ filter head in the garage, only to soon learn those won't fit on the LB7. So he runs to town and grabs a filter head rebuild kit. We pop that on it, and problems solved. Seems the cold weather and a leaky head was allowing it to suck air. Lucky guess.. Truck fires up, idles fine. He say you drive it to the shop and see what ya think. Get out on the road, roll into it, and looks like any cranked up LB7 in the mirror. For about 2 seconds, then falls on it's face, but recovers when ya let out of it. So I grab the V2 and back out to log some data. As suspected, it's no where near command FP when boosted. Saw it hit 12k psi, then dropped off to about 3000..
Back at the shop I start inspecting the engine a little closer. Besides an air raid tube and filter not much to see. It's got new head Bolts, but not studs. Previous owner said heads were just redone. Also find it has a new looking FPR, along with worm clamps on every rubber fuel line. Which tells me, that somebody was chasing what they thought was and air leak. But they never rebuilt that head.. Was 100% Original. We had to slit the lines to get them off it. So who replaced all the clamps??
Last thing before calling it a day, I cranked the FP up and down with the V2 and logged some data. What I noticed is the regulator has virtually no control on the pressure, and she won't make 10k psi at idle. But it's also running above commanded at idle, and never drops when commanded down. Can't kill it by pulling the pressure either..
So before writing off the pump, figured I should check all the boxes and verify the return on injectors and that shinny regulator.. So was gonna hook a jug of fuel to the filter head and start there. And was gonna do a vac test since my ex-Dmax-tech buddy just happens to have the gauge kit. But when I popped the hose and bolt off the test port, there was fuel in it.. Hit the primmer, and fuel is leaking past that schrader valve. I said it was worth the wait... LOL
While dive any deeper into this rolling fuel leak, anyone care to bet on findings??
I tried to tell my buddy that I know nothing about the LB7's. Then he quickly recalled how I needed one for testing the FUCM project.. To which I said, I have an Lb7 on the bench that runs perfectly fine, an requires no fuel.. Didn't work. He said you have keys to the shop, send me the bill, and quickly left town.. Setting here recalling why I never cared for the Lb7' looking at this graph from FPR testing. I was given a couple hints from my tech buddy on reading FPR data on these to determine cause. But with the fuel leaks I've found so far, and way regulator is acting, I'm gonna keep an open mind on this one until I hook a jug directly to the CP3...
Truck came with an Edge of same era, so he was able to at least read and clear the codes. I told him to monitor the FP, and change filter if it persisted. Never heard anything more, until next day when I get a call that truck made it home, but when he went out next morning, wouldn't start.. Pumped the primer, fires right up, dies in under 60.. I ask, did ya change filter? Nope, limped it on home he said. Popped low pressure a couple more time in mountains, but towed 12k lbs no problems. Humm.. Ok, lets grab a filter and toss it on.
While installing the filter I noticed someone had installed worm clamps on the filter head, and electrical taped all the fuel line they could reach. Troubling.. As anyone who's owned a diesel for a few days knows electrical tape and diesel fuel don't mix. But they were obviously chasing some rabbit, and covered all the bases.. Even put a hose with a bolt in it over the vac test port.. I can tell this is gonna get interesting. So stick around..
I found an old LBZ filter head in the garage, only to soon learn those won't fit on the LB7. So he runs to town and grabs a filter head rebuild kit. We pop that on it, and problems solved. Seems the cold weather and a leaky head was allowing it to suck air. Lucky guess.. Truck fires up, idles fine. He say you drive it to the shop and see what ya think. Get out on the road, roll into it, and looks like any cranked up LB7 in the mirror. For about 2 seconds, then falls on it's face, but recovers when ya let out of it. So I grab the V2 and back out to log some data. As suspected, it's no where near command FP when boosted. Saw it hit 12k psi, then dropped off to about 3000..
Back at the shop I start inspecting the engine a little closer. Besides an air raid tube and filter not much to see. It's got new head Bolts, but not studs. Previous owner said heads were just redone. Also find it has a new looking FPR, along with worm clamps on every rubber fuel line. Which tells me, that somebody was chasing what they thought was and air leak. But they never rebuilt that head.. Was 100% Original. We had to slit the lines to get them off it. So who replaced all the clamps??
Last thing before calling it a day, I cranked the FP up and down with the V2 and logged some data. What I noticed is the regulator has virtually no control on the pressure, and she won't make 10k psi at idle. But it's also running above commanded at idle, and never drops when commanded down. Can't kill it by pulling the pressure either..
So before writing off the pump, figured I should check all the boxes and verify the return on injectors and that shinny regulator.. So was gonna hook a jug of fuel to the filter head and start there. And was gonna do a vac test since my ex-Dmax-tech buddy just happens to have the gauge kit. But when I popped the hose and bolt off the test port, there was fuel in it.. Hit the primmer, and fuel is leaking past that schrader valve. I said it was worth the wait... LOL
While dive any deeper into this rolling fuel leak, anyone care to bet on findings??
I tried to tell my buddy that I know nothing about the LB7's. Then he quickly recalled how I needed one for testing the FUCM project.. To which I said, I have an Lb7 on the bench that runs perfectly fine, an requires no fuel.. Didn't work. He said you have keys to the shop, send me the bill, and quickly left town.. Setting here recalling why I never cared for the Lb7' looking at this graph from FPR testing. I was given a couple hints from my tech buddy on reading FPR data on these to determine cause. But with the fuel leaks I've found so far, and way regulator is acting, I'm gonna keep an open mind on this one until I hook a jug directly to the CP3...
