New fuel pump, fuel filter, and starter. Still not starting

[Timireland77]

I have a 99 Yukon with the 5.7L. I just replaced the fuel pump, fuel filter, and starter and it won't start. I'm getting fuel to the throttle body. It acts like it wants to fire but won't. Any help would be appreciated. Time up is less than a year old as well.

 

[Timireland77]

Tune up. Autocorrect

 

[east302]

Assuming you have good spark (do you have a spark tester?), a fuel pressure test would probably be in order. Spec is 60-66 psi with key on, engine off. Watch to see if it drops when the key is turned off.

If you have a scanner, see what the engine coolant temperature sensor is reading. This is the one by the thermostat, not the one on the driver side head. If it’s reporting an oddball number, it’ll throw off the computer and can flood it. A workaround is to hold the gas to the floor when cranking. This temporarily stops injector flow but is more commonly noticed on hot starts.

 

[Fless]

Tune up. Autocorrect

Note that you should have an EDIT button at the bottom of your original post. Easy enough to change that instead of adding another post.

 

[B-train]

Do you hear the pump cycle with key on, engine off? And, while you said the tune up components were a year old, there is a known issue with the distributor cap for that model. Some manufacturers had a bad run and they would fail prematurely, or cause a crappy running condition. Might be worth a quick look for cracks or arcing as well.

But, do as others have stated above and check spark, fuel pressure, and coolant temp as well.

 

[Timireland77]

Assuming you have good spark (do you have a spark tester?), a fuel pressure test would probably be in order. Spec is 60-66 psi with key on, engine off. Watch to see if it drops when the key is turned off.

If you have a scanner, see what the engine coolant temperature sensor is reading. This is the one by the thermostat, not the one on the driver side head. If it’s reporting an oddball number, it’ll throw off the computer and can flood it. A workaround is to hold the gas to the floor when cranking. This temporarily stops injector flow but is more commonly noticed on hot starts.

So I have 64 psi and spark is good. I've seen some people say it may be the crankshaft position sensor. It will crank and crank but not start. My battery isn't liking that. Is the crankshaft position sensor my problem then?

 

[east302]

B-train mentioned distributor caps. I’ve had one (new, actually) that failed. The spark on the particular cylinder was there, but was weak compared to the others. Delco caps used to be the ones to go with but that’s been a few years now.

Did the fuel pressure hold within a few pounds after the key was turned off?

Hold the gas to the floor and see if it fires.

 

[B-train]

That motor has crank and cam position sensors. That is also a possibility. If I remember correctly, I thought the engine would run if 1 failed, but in more of a safe mode. It's be 25 years since I worked on those..... I do remember a customer truck that has a bad cam sensor and I thought it would still run, but turned the CEL on.

Does your truck have a mass air flow sensor? If so, disconnect it and try to start it. If they fail, you can unplug them and the ECM defaults to a base map as a limp mode.

 

[Mater]

start with the basics does it have fuel, spark, compression?

 

[exp500]

Spark Test at Coil and Dist, When was last cap/rotor /wires?

 

[strutaeng]

It's most likely a distributor/rotor/cap related problem.

Those can be annoying to resolve because it can be an intermittent no fire. Sometimes moisture or cold weather causes it. Or there's a worn shaft or gear worn in the distributer shaft. It fools you because you'll have spark and everything else needed, but engine still won't fire. I think what happens is the spark jumps around in the cap, and goes to the wrong cylinder somehow. If it's wet or humid, put a heater or hair blow dryer toward the distributer and let it heat up for 45 minutes and see if that does it. Remove the cap and see if there's excessive play on the rotor; crank the engine and make sure the rotor rotation seems consistent with engine rpm. Aftermarket caps are notorious for having crank-no-fire issues and short lives on these engines; most guys carry an extra spare cap on their glovebox.

Yes, engine will start and run w/o cam position sensor. Some aftermarket cps seem to also cause starting issues. You'll need a scope to properly diagnose that.

 

[Eman85]

I have a 99 Yukon with the 5.7L. I just replaced the fuel pump, fuel filter, and starter and it won't start. I'm getting fuel to the throttle body. It acts like it wants to fire but won't. Any help would be appreciated. Time up is less than a year old as well.

Run that fuel to the throttle body part on a 99 past me again.

 

[Timireland77]

Spark Test at Coil and Dist, When was last cap/rotor /wires?

Less than a year old on all of those.

 

[Hoesgottaeat2]

I had a new distributor cap fail causing a crank/no start less than a year old. Just last year.

 

[Mater]

yup i have had a brand new rotor just fall a part less then a year. now i have gotten into the habit of checking new parts first just do to the recent quality hit even on GM parts