Hello, this is my first time posting in a thread. I recently picked up an 89 f250 4x4 with the 5.8, zf 5. Was able to drive her home but the more it warmed up the harder it was to drive. Almost seemed like it was struggling to get fuel. Mashing the throttle down, from second gear on up, would show little to no response and sometimes bucked a little (Like my carbed 460 when the fuel filter was clogged up). But if I let up of the throttle it would pick back up. Well I got home and went to the parts house. picked up motorcraft plugs, duralast wires, cap and button, fuel filter, fuel pressure reg., and a Pcv valve. I had no clue when they were all changed last so I figured it needed to be done anyhow. Put all those parts on and fired her up to check the timing. Almost 20* BTDC. Moved that back down to 10-11* BTDC and it's a new truck. Then changed the oil. As soon as I cracked the drain I noticed what looked like a few drops of water? Maybe fuel although it didn't reak of gas. The prior owner said he changed the water pump. Could some of the water have gotten in then? I believe that there was 2-3 quarts over full of oil that drained out. Why?

Decided to do a few diagnostic tests after that. Hooked up a fuel pressure guage.
With vac hooked up 32lbs
w/out vac hooked up 42lbs
Then I shut the truck off and the pressure was about 32lbs and stayed there for ten min or so. Decided to take shower and eat. About 45 min later it was at 16lbs then an hour later it was 0. Shouldn't it stay at the 32 or is it supposed to leak down? Did the self-diagnostic test and it came back with Code 41 HEGO circuit lean. Do I have bad injectors? Thank you for your help in advance

 

Bump, sounds like the same problem i have, new pump, tank and regulator and gets 32 lbs at the most

 

The fuel pressure bleeds down over time so no problem there, should retain 5psi of specified value for 1 minute after key is turned off.

The pressure values you posted, With vac hooked up 32lbs
w/out vac hooked up 42lbs are well within spec.

 

huh, a guy with the same truck as mine gets 50 psi

 

huh, a guy with the same truck as mine gets 50 psi

Does his truck have a 300 6? if so that's the correct fuel pressure at an idle, if not he has a over pressure issue. Bad enough to worry about? maybe, depends on cause and effect.

A 89 351's fuel pressure spec is 30 to 45lbs at idle. Pressure should increase 5 to 10 psi with vac line disconnected so his readings are fine.