Hi guys,

I think I know the answer to my question. I did a quick search on here before I posted this new thread, but the majority of the threads only dealt with diesels.

So, here goes. A little background. I bought the 2008 F250 XL, 5.4L with 145,000 miles in December. It had a bad engine (dropped valve). I had the engine replaced with a remanufactured one (Performance Products) and started driving it this month. To date, I have put about 700 miles on it with an oil/filter change at 500.

So, here is the newest problem. Yesterday I finished changing my body mount bushings (with Daystar polyurethane ones) and went for a test drive. When I started the engine, a smoke cloud caught my eye. I took a closer look and noticed it was a gray smoke. I jumped out and ran around to smell the smoke - it had a gas smell. I did not test for smoke after my test drive.

So here is my question. It is obviously burning excess fuel on startup. That would mean that one or more injectors are leaking down after shutdown, correct? Testing this would be done by performing a leakdown test? How do I go about doing this WITHOUT any special equipment?

Thanks for the info.

 

Bump to the top.

 

I started using Lucas fuel injector cleaner right after I posted this. So far I haven't seen the smoke again. I don't know if it was one time thing, or whether the cleaner did it's job that quick. Whichever it is, I hope she's cured for good!

 

Let us know if the symptoms return.

 

I will do that.

 

The 2 valve trucks have been known to do put out a puff of smoke at startup. This usually was after the truck was started, run for a minute or so and then shut off. I noticed that my truck and my dads truck did not do it anymore after the stock exhaust was replaced with an exhaust that is more free flowing. I always figured there was a build up of fuel in the engine, and or exhaust which caused the puff of smoke on restart.

 

That could've been what happened with mine that day. When I moved it to my shop, it only ran around a minute before shutting it off. I usually let it run for a minute until it stabilizes at slow idle before I move it. That time I jumped in, cranked up and moved to the shop - I guess I was in a hurry to get started on those body mounts, LOL!

 

Just for what it's worth, ruling out injector leak down only requires a fuel pressure gauge. They're relatively inexpensive, and you're checking for rail pressure drop after shutdown.

Also, you will hurt nothing by putting it in gear immediately after startup. Full oil pressure reaches the heads in seconds, waiting a minute isn't going to help anything.

 

I have fuel pressure gauge, but where exactly do you hook it up on the 5.4 rail?

Letting it come off of high idle before putting it in gear is something that I have done ever since I've been driving - maybe it's a holdover from the manual choke carb days. I do it with my military vehicles because the Jeep has a manual choke and the deuce has to warm up before being driven.

 

I do the same with my trucks. I don't see it being a bad idea to let everything circulate a bit and let temps come up off of dead cold a bit before heading off.

 

Our '09 F-250 330 (5.4) will puff a little cloud of gray smoke on start up. It does this very infrequently but I've seen it following maybe a half dozen start-ups in 3 years and the 20,000 miles that we've owned the truck. This smoke on start up catches my attention but everything seems to be working properly, oil never goes down on the dipstick and the truck runs perfectly. Until we have reason to believe it's a problem that needs attention we won't investigate.