When the temp is below 30F, the truck really struggles to start and sometimes won't start at all. It has plenty of cranking power, and after reading about the fuel pressure regulator I'm convinced it's a fuel problem. When I pulled the vaccum hose off of the regulator, it has zero gas present in it but does smell like gas. The nipple that the vaccum hose connects to on the regulator does have a little fuel on it each time I pull the vaccum hose off.

Would folks agree that this points to the fuel pressure regulator.....any other tests I could do to confirm?

Other than the cold temp start, the truck has zero problems starting in warmer weather and runs just fine once it's going.....just the starting problem.

 

I'd check the fuel pressure as well to make sure its not a pump problem...

 

Changed fuel pressure regulator, but it didn't really fix the problem. I have to crank over 3 or 4 times with the gas pedel down in various positions to get it going. Fuel pressure tests show 50 psi w/ the key on/engine off....running its around 52 psi. Is 50 psi on the weak side and causing this hard start? Thanks.

 

Just installed brand new fuel pump yesterday. Tried to start this morning, it was 12F outside and still does the same thing. Had to crank 5 or 6 times with the gas pedel pressed in various positions before it started.

So far my I've replaced the following in the last month....

Plugs, fuel filter, fuel pressure regulator, fuel pump.

I'd tested the engine coolant temp sensor, and it passed. Thoughts on what to look at/test next???? It's starting to baffle me........I get an intermittent P0137 oxygen sensor code in the cat converter, but I don't think that's the problem. The only problem remains hard starting under 30F outside temperature.

 

....and also have cleaned the MAF and sprayed ether like crazy around the intake with no success. You can smell gas if you stick you nose near the exhaust pipe during a failed start.

Injector problem??? How to test???

 

Fuel pump and fuel pressure regulator has been replaced. Now I'm getting a buzzing/humming sound coming from what I think is the regulator. When I pull the vacuum line off the regulator, the buzzing/humming stops. When I crawl under the fuel tank, I can feel the vibration in the middle line.....I don't feel it in the supply line. I'd replaced the fuel pump w/ the same name brand (delphi) as the original.

PLUS....my original problem of 1st start hard starting still exists. I just triple-checked fuel pressures.....54-55 psi key on, 48 psi running/idle, 58 psi after I pull the vacuum off of the FPR. Almost 0 psi leak down after 5-10 minutes. I was suspecting injector leaks, but I think that's not the case with no obvious leak down.

SO...thoughts on buzzing? Hard 1st start?

 

What kind of motor oil are you using?

 

Can anyone describe how to replace the camshaft position sensor on a 2000 5.3L. I'm still trying to fix the cold start problem.

I was shown a photo that it's located on the top/rear of the engine block. When I find that area on my block, there's a connector that plugs in vertically to a sensor. However, the new sensor I have plugs in horizontally.....so I'm questioning if that is really it. Also, it looks like I'd have to take off the whole intake manifold just to get to it....absolutely no room to work.