Engine/Transmission (1998.5 - 2002) Intermittent hard start 01

[VolsFan]

Only started happening with the new FASS titanium install, and it's sporadic . When it does do it I bump the starter and let the lift pump run and then it'll fire up. Runs great no codes. Seems like it does it after its set all night

 

[KATOOM]

Are you absolutely positive its sporadic? Hard starts are generally not random but tend to follow specific situations. For example: does your truck hard start in the morning when the engine is cold or has been sitting for many hours? Or does it hard start when the engine is at operating temperature and you shut it off at places like the gas station or store only to find that it doesnt want to start very easily? If you say both then the diagnostics will be different.

 

[VolsFan]

Yeah I see your point. It isn't that sporadic then. I can run it all day and be fine. Then on some mornings it will act up. It's like the pump doesn't activate and I got to bump the starter to prime the VP. I let it set for a week and fired up fine, ran it the next morning and did it again. Did it this morning but ran all day fine. I've taken it on an 8 HR trip and no problems. Haven't seen any leaks

 

[KATOOM]

Given that the hard starting experience only happens when the engine is cold.....and also followed the install of the FASS, the cause of the hard start is 99.9% because of a fuel leak.

Whats happening is the fuel lines are supposed to remain full of fuel at all times. Even with the engine off, pressure will bleed off but fuel always stays in the lines and is not supposed to exit the lines. This is called a "prime" and is the reason why the FASS cycles the 2 seconds upon turning the key to ON.

Because of the prime, if there are ANY fuel leaks at any of the fittings then a small amount of air will be allowed to enter and the fuel will drain out of the line back into the fuel tank via gravity. Think of it like holding your finger over a drinking straw in a glass of water. Lift the straw out of the glass and the water will remain in the straw as long as your finger is sealing the top. But remove your finger and the water drains out. Same thing going on with your fuel lines.

The larger the leak is, the harder it will be to start the engine, and the shorter the time frames will be between hard starts. Meaning a slight leak will only be trouble in the morning or after sitting a long time, but a severe leak will be a problem if the truck only sits for a couple hours.

To assure yourself if this is truly the problem, the way to diagnose whether or not there's a leak is to park with the nose of the truck pointing downhill. This effectively raises the level of the fuel tank in relation to the engine and fuel lines and keeps gravity from pulling the fuel out of the lines back into the fuel tank. If the truck starts normally after being parked like this overnight or however long it sits then without a doubt there's a leak somewhere.

Fortunately diesel is more like oil than gasoline and will creep around before it evaporates so what you get is a very thin layer of oil residue in areas where the fitting isnt perfectly sealing. One way to find a leak is to wash the area off with warm/hot water splashing over and then let it completely dry. Then dust with baby powder and start the engine. Can be messy though..... Or just feel around with a clean hand on ALL the fittings you touched and/or messed with during the FASS install. I'm sure you'll find one or more fittings isnt sealing like you thought and may need to be snugged up.

Something worth knowing too is what fittings you have. I'm going to assume that the Titanium kit came with JIC fittings. If so then they seal very good but sometimes need some persuading.

Lastly, there are two other notorious leak locations. 1) the single banjo bolt on the drivers side back of the head for the return line and 2) the "T" fitting found just below that banjo bolt. If either is leaking then snug the banjo up to 18 lbs and try tightening the "T" fitting. But DONT mess with them if they aren't leaking or if you find other leaks because you dont want to cause a leak on something currently not leaking. There's a general rule of thumb with these fuel lines..... Do not mess with any fittings or open any fuel lines for any reason unless you have to (like changing fuel filter) because it not only causes fittings to leak but it allows air to enter the system which then has to be purged out over time.

Hope than helps.

 

[VolsFan]

Thanks for the help. I already had a big line kit installed so I didn't mess with fittings at the injection pump. I kept the stock fuel filter and sure enough there was a leak at the fitting feeding it. Hopefully this resolves the issue!
update- fired it up this am and started flawlessly, think thats all it was! I did notice that it took a crank or two longer to fire most people wouldn't have noticed but back to normal now.