The other day I replaced an HPOP in a bus that quit . Now I have the bus running . Well I had a bus break down last fall and we parked it because I thought the ECM was bad . I checked codes and got a lot of codes saying bad IDM and ECM . I did all the checks and found the grounds were rusty . Cleaned and retighten them codes went away but no start . So I figured this summer take another look .The first bus made me think maybe HPOP . So I hooked up the charger and put a gauge on the supply line to the head . After charging I cranked on the engine and got like 175 to 200 lbs. pressure . The reason I am questioning is . The first bus just died with no warning . This bus ran with warning lights coming on . Was loosing power but made it back to the garage .Could really low pressure keep it going while it's running ? Is there any reason for the low pressure other than it's shot ? Thanks and sorry it's long
If your gauge is just connected directly to the output of the pump then that defiantly is to low pressure. Would still have to make sure the supply to the pump is good and there is no issues with the ipr but it is a pressure supply issue. I take it your working on a 466, what we have is a porta power filled with engine oil, I had short hoses with fittings made up for the 466, 7.3 and the 6.0 as well. If I suspect a low hpop problem on the scanner I disconnect the line to head, install the porta power and I should get 1,500 psi within 3-4 pumps and it should hold 600 psi no problem .If this is good than everything under the valve cover is good and I have a pump/ipr/supply issue[99% time pump issue]. If I can not build or hold pressure I am 100% sure the problem is under the v/c. Had it for the 7.3 and have just been making up new adapters as the engines changed.
Yes it's a 466 and I couldn't get my scan tool to show pressure . So I made a gauge to fit on a lie coming off the pump .Haven't looked at the IPR yet .
Another HPOP problem
Posted - 06/11/2015 : 8:46:16 PM
