Hey I need help diagnosing an issue with my idi. It didn't start till recently when I was on my way to pick up a mustang 3 and a half hours away and I was forced to drive it the whole way back like this so I don't know If I damaged anything worse but here are the problems. When idling it shakes and vibrates like hell and idles rough but starts just fine but after starting it also sound like it's running on 4 cylinders and sometimes 8, when driving and giving it a bit of gas it leaks fuel from somewhere but I have no clue where because it spews everywhere but doesn't leak when idling(or from what I could find it doesn't) it has now power, shakes when accelerating and leaks about as much if you slam on the brakes. I don't know what it is and no one else I've asked does either. Thanks for your help.

 

Get a friend to stay on the throttle while you're looking for the fuel leak. Obviously make sure truck is in neutral or park and can't jump and kill you (use a non-moron friend).

I've had injectors loosen up in the heads and the respective cylinders will lose compression and power accordingly. Drove home few hours away on 7 cylinders once, while towing even!

Cracked injection lines are a thing too with these engines, typically when the vibration damping clamps that hold the lines together in several spots are missing.

 

Thanks for the help I found out its not leaking from any of the injection lines but still have no clue where it's coming from other than the right side of the engine bay and it hardly leaks while in park and neutral

 

The right side of the engine is sitting in the drivers seat.
Are you referring to the right side standing in front of the vehicle?

There is the hard line that returns fuel from the IP, it runs down
the drivers side to the rear of the engine to a fitting where the return
from the return caps from both sides come together.
The Pass side comes across behind the back of the engine to this
fitting. It then runs down the back of the engine, it is a rubber hose
that connects to a metal or to the plastic fuel line which ever tank you
are pulling from.

The hard return line from the IP has a rubber seal on ea end called an
"Olive". If these have never been changed, they could be the source of
your leak.

There is on the Fire Wall by the Brake Booster a Water separator, they
were a possible cause of air intrusion and were eliminated or the 2 hoses
going to it connected together in a loop. If these are original, they are
probably a cause of a leak.
I changed mine about 3 years back, and were stiff and cracked after 30 years.

As mentioned, you need the clamps on the hard lines to the Injectors to keep
the lines from vibrating. If they do vibrate, they can crack and spray fuel. Only
fix is to then replace the leaky line and add the clamps.

One note: The return lines are not under pressure, or very little.
The pressure lines are the hard lines from the IP to the Injectors.
The fuel lines from the tank to the Lift Pump are under a suction, as the LP is
pulling fuel from the tanks.

You might need to clean off everything to see where the leak is coming from.

Charlie