Starting problems

[diesel53149]

Hi All,
New to the site, so please excuse if this subject has been covered recently. I'm looking at a '95 F250 w/7.3. It has 197K original. Cranks fine, but won't even fire unless the throttle pedal is depressed at least 1/4. Even then it fires unevenly and runs rough for the first few seconds. After it finally starts, it will idle and drive OK. No smoke on start up, I expected to see a lot after it took several trys to get it going. The owner says it has always started like that during the year or so that he has owned it. No noticeable smoke going down the road, but I didn't really romp on it.

Another question: the engine shows some blow-by out the dipstick tube and more if the oil fill cap is removed while the engine is running. I'm surprised that there isn't a corresponding amount of oil smoke in the exhaust. Am I looking at a tired engine?

I'm an experienced heavy diesel (Detroit, Cummins) mechanic but have no experience with these engines.

 

[F250Jockey]

If you're really interested in this truck, I'd scan it for codes.

Also, pull the intake boot off going into the turbo compressor, and check the turbo compressor blades for damage. This will tell you if the engine has injested anything, which would likely damage it internally.

What you described isn't normal!


Just my $0.02

 

[Tbar]

Starting problems + blow-by out the dipstick tube = sounds like a compression problem to me.

Rings, valves..................???


Tbar

 

[diesel53149]

My experience with diesel engines in general is that low compression will result in white smoke (uncombusted fuel) on start-up, diminishing as the engine warms up. Some Cat 3208's would do this from new especially in cold weather due to their unique compression ring design. This 7.3 did not smoke, which is puzzling considering the hard starting and blow-by. Like I said, not experience with P-strokes, but it seems like it could be a TPS related issue as it does not fire at all without the throttle depressed.