7.3L freshen up

[cmann250]

My dad has a '97 7.3L. I suspect he injectors are bad, but it's been a while since I've dealt with a Ford.

The injectors have 270k on them. In the past few months, the truck has seemed down on power and fuel economy has decreased. If it sits for some time (over 2 days) it is harder to crank back up than it should be. It always smokes white with a heavy fuel smell for 5 or 10 seconds upon start up.

Sound like a valid theory? If so, is there a test I can perform that confirms it?

If the injectors are indeed bad / going bad, what else should I replace while in there? In the last ~100k miles, the valve cover gaskets, UVCHs, and fuel pump has been replaced. Does any of the high pressure oil system need attention?

Many thanks, from a dinosaur diesel owner :Cheer:

 

[oldestof11]

I'm ford tupid.

I would think the HPOP would be the problem vs injectors. Injectors would be a hard start every time when cold vs sitting.

The sitting thing leads me to believe the HPOP is leaking down and it needs to prime the system.

If those don't fix it, bad ground. :lolly:


Sent via USPS 2 weeks ago

 

[biggy238]

Sounds like low fuel delivery pressure to me. Does it restart more easily when its hot?

Monkey Fist Rage

 

[Pocket]

Old worn out injectors tend to smoke a bit more on cold starts than warm. Problem is that unless you have a flow bench, you aren't going to be able to really test them. Any normal testing equipment with a laptop running buzz tests, etc will just show you the electrical side only.

You could pull the valve covers and start the truck when cold. Watch the oil spouts and see if some of your injectors aren't flowing oil out normally. I diagnosed a bad stock injector that way, replaced it, and problems went away for almost a year until another decided to get tired. At that point I had enough and yanked them all out.

With that kind of age and mileage on the original injectors, it wouldn't surprise me if some were getting to the point of needing replacement.

Of course you could also test fuel pressure and oil pressure to the injectors to make sure both of those are normal. Once those are ruled out, it's likely time to swap sticks.

 

[cmann250]

Does it restart more easily when its hot?

If I drive it for 20 minutes, shut if off for 5 minutes, and restart it, it starts fine.

Of course you could also test fuel pressure and oil pressure to the injectors to make sure both of those are normal. Once those are ruled out, it's likely time to swap sticks.

Where can I get those readings and what should they be? If both of those check out, I can pull the valve covers and see what the oil flow is like. If one is bad, they are all getting replaced because the rest are surely not far behind.

If those don't fix it, bad ground. :lolly:

My thoughts exactly.

Thanks guys.

 

[cmann250]

I've found that fuel pressure is supposed to be 45-65 psi, but I've net tested it yet. Is it safe to assume that I'd have a code for ICP if the high pressure oil was not within spec?

Thanks.

 

[Pocket]

Where can I get those readings and what should they be? If both of those check out, I can pull the valve covers and see what the oil flow is like. If one is bad, they are all getting replaced because the rest are surely not far behind.

Fuel pressure has to be done manually by tapping in with a gauge.

ICP can be logged with a compatible scan tool/datalogger.

I've found that fuel pressure is supposed to be 45-65 psi, but I've net tested it yet. Is it safe to assume that I'd have a code for ICP if the high pressure oil was not within spec?

That's about right for fuel pressure, but it can vary. Just because it's say at 30 psi doesn't mean that's the culprit. These trucks can actually start and idle with barely above zero fuel pressure.

As for ICP, you may or may not trigger a code depending on the situation. For instance, if you're having a hard time building ICP while cranking, it typically takes 20 seconds worth of nonstop cranking to trigger a code. If you never run your starter that long continuously, you'll never set the trigger.