Cascade Crew

iansane · Posted: Mon Jul 05, 2010 5:10 pm Post subject: Hard start when cold?

I've been having this problem when my car has been sitting for at least a couple of hours. Such as overnight in the garage or it was really bad last night after sitting outside all night at my girlfriends. When warm it cranks and fires fine.

The car is crazy hard to start. It cranks and cranks and will occasionally hiccup a bit out the exhaust. The crank time has been increasing over the last week or so. It eventually starts though. Once it has, it seems to run and drive fine. Gas mileage is the same. At idle I occasionally get an extra burble through the exhaust but the idle seems consistent. My tach isn't correct so I'm not exactly sure what the idle is at. I think around the factory tahoe ~600rpm. I get no CEL but I have no scanner to get the actual sensor outputs. I hear the fuel pump priming when I switch to key-on. I haven't been able to check fuel pressure yet because I loaned out my gauge and haven't gotten it back yet. (anyone up north want to loan me one for a night? Very Happy

).

I thought maybe an injector or two was leaking and filling a cylinder but with the rail pulled off and primed, nothing leaks onto a paper towel. LS1tech suggested check valve in the pump?

Twilightoptics · Posted: Mon Jul 05, 2010 5:16 pm Post subject:

The newer GM stuff like that is way more finicky about pressures to start. Definitely get a gauge on it. I've got one, haven't used it in forever though LOL!

Assuming the electrical is all correct and good, I might suspect vacuum leak or a plug giving you some trouble.... but fuel system is definitely to watch. I know with my C950 and walbro, pressure bleeds down like crazy after the prime which is fine for my motor, but would cause your problems.

aaron_sK · Posted: Mon Jul 05, 2010 5:20 pm Post subject: Re: Hard start when cold?

iansane · Posted: Mon Jul 05, 2010 5:29 pm Post subject:

Twilightoptics · Posted: Mon Jul 05, 2010 5:35 pm Post subject:

Depends on how your pump hooks in. If it's hardline into the pump, it shouldn't be an issue. If there is a 3/8" fuel line with hose clamps connecting the two then you could have a problem.

It shouldn't run well at all if that was the case because if never builds proper pressure.

I'm in South Seattle next to Boeing. Might be up for a drive Wink

Engine is hard to start after a heat soak of 15-30 minutes.
Tests/Procedures: 1. Remove the vacuum hose from the fuel pressure regulator on the driver's side center of the intake manifold. Check for gas to spill out of the hose.

2. Lift the injector rail and check for dripping fuel injectors.
Potential Causes: Fuel Injectors
Fuel Pressure Regulator

Engine is hard to start after a hot soak.
Tests/Procedures: 1. Install a fuel pressure gauge and check for pressure to bleed down after the engine is shut down.

2. Remove the vacuum hose from the fuel pressure regulator on the driver's side center of the intake manifold. Check for gas to spill out of the hose.

3. Try blocking off the feed and return lines to isolate where the pressure is bleeding off.
Potential Causes: Fuel Pressure Regulator
Fuel Pump
Leaking Injectors

Lots and Lots and LOTS of Fuel Pressure Regulator failures posted for Tahoes with the 5.3L

iansane · Posted: Mon Jul 05, 2010 5:48 pm Post subject:

Only issue there is I have the fuel system from a 'vette. Very Happy

Corvette filter/regulator down under the car in stock thirdgen filter location, single pressurized line going up to the fuel rail dead-headed.

I honestly don't remember how it hooked in. Been so long, factory TPI method I presume. But yeah, it runs fine.

chevymad · Posted: Mon Jul 05, 2010 5:49 pm Post subject:

If its not fuel it could possibly be a weak crank sensor as well.

Twilightoptics · Posted: Mon Jul 05, 2010 6:06 pm Post subject:

What year did they go to single up system?

It'd be similar anyway I'd think.

Didn't see any crank sensor issues posted.

aaron_sK · Posted: Mon Jul 05, 2010 6:10 pm Post subject:

iansane · Posted: Mon Jul 05, 2010 6:14 pm Post subject:

The vettes? Not sure. My fuel rails are from an '03/04 from the part number.

EDIT; It's all 6an braided line from the rail to the filter/regulator and back up to the tank. So it'd be hard to block off...

Twilightoptics · Posted: Mon Jul 05, 2010 6:17 pm Post subject:

iansane · Posted: Mon Jul 05, 2010 6:25 pm Post subject:

Nope. Braided all the way to the rail. And the rail itself is pipe. The only rubber is the vent line off the tank.

Is it even worth it to ghetto check the pressure by pressing the schrader valve in the morning? I guess that'll just tell me if there is fuel at all...

Twilightoptics · Posted: Mon Jul 05, 2010 7:28 pm Post subject:

Hehe that's pretty ghetto. Lets rock the gauge :O)

Like I said, they're very picky about pressure. FUEL doesn't mean start :O)

iansane · Posted: Mon Jul 05, 2010 7:43 pm Post subject:

Hey, I did live Tacompton... Laughing

As long as the car starts, you mind if I stop by sometime tomorrow to borrow the gauge for the evening/morning?

Al Hasse · Posted: Mon Jul 05, 2010 7:54 pm Post subject:

I can bring my gauge up to work tomorrow. You can swing by about noon. Give me a call first so I can get it to the front lot.

iansane · Posted: Mon Jul 05, 2010 8:17 pm Post subject:

Sweet! Thanks Al!

Al Hasse · Posted: Mon Jul 05, 2010 8:24 pm Post subject:

No problem. I break at 10:00 and and take lunch for 1/2 hr between noon and 1:00. I'll ask the boss (I vanpool with him), and see if I can show you around the shop for short tour, I'll need to get you badged in. No promises, we are kind of busy. Call me before you come over Cool

iansane · Posted: Mon Jul 05, 2010 8:27 pm Post subject:

Cool, call you around noon then?

Al Hasse · Posted: Mon Jul 05, 2010 8:45 pm Post subject:

Sounds good.

RSFreak · Posted: Mon Jul 05, 2010 9:00 pm Post subject:

I got a fpg up here in Renton too or my other one is down at James' house in case you still need one. Or you could just spend $10 at Harbor Freight. Wink