Mazdax605 UltraDork
11/15/16 6:48 a.m.

Hello all,

Just the past two days I've noticed my 04 Suburban has not been starting super fast like it usually does. It usually starts with half a revolution it seems. As a matter of fact it often doesn't start on the first try. It hasn't been wet, but today will change that. It has been up and down with temps if that matters, but not super cold/warm.

Plugs, coils, other?

162K miles 5.3 litre. I've owned it since 117K Jan/Feb 2012. I've not done the plugs/coils. If plugs, are they difficult? If coil/coils, which ones are best to buy? How would you determine which coil/coils may be bad? Expensive job to do myself?

Streetwiseguy PowerDork
11/15/16 7:05 a.m.

Unlikely to be ignition- the way a modern ignition fails, it will almost always just lose a cylinder due to a coil failure, or spark plug problem.

Do you have a fuel pressure gauge? Its more common on the traditional small block with modern fuel injection, (99 and older) but GMs start very poorly if they don't have the full 60psi while cranking. I have seen it quite regularly where the pumps get a bit weak.

Mazdax605 UltraDork
11/15/16 7:09 a.m.

I do not have a fuel pressure gauge, but I know I can borrow one. If it's the pump, where does that reside? Nightmare to replace?

Sonic SuperDork
11/15/16 7:51 a.m.

Fuel pumps on these are a known problem issue. My 03 Sub had an issue where something was stuck in the check valve that it would lose pressure when sitting and it made it very hard to start. I would cycle the key a few times before starting and that helped, while waiting for a good time to drop the giant gas tank to replace the pump. Fortunately the blockage seems to have cleared and it has been fine for the last 2 months.

Changing the plugs and wires is very straightforward, it took me an hour taking my time, the hardest part is needing a stool to stand on to be able to get up high enough over the fender to drop down into the engine bay.

Ranger50 UltimaDork
11/15/16 8:02 a.m.

Typically fuel pump related on long cranks. Replace with Delco/GM only, unlesss you like replacing them every year afterwards.

Mazdax605 UltraDork
11/15/16 8:09 a.m.

So after looking at the pump on rock auto it appears to live in the fuel tank like most other pumps. With my luck it will fail fully when on the rare occasion I have a full tank. I'm guessing I'll need to drop the tank and need special tools for the line connections?

dropstep Dork
11/15/16 8:17 a.m.

Line connections should just squeeze to unhook. Atleast my s10/silverado both do. Lines are the easiest part of the job.

Id certainly run a pressure check first. The 5.3 has an easy too reach schrader valve.

imgon Reader
11/15/16 3:35 p.m.

Any chance it is just a weak/ dying battery? Swing by Advanced and have them test it

Mazdax605 UltraDork
11/15/16 3:37 p.m.

Battery is only a year old or so. I have a midtronics battery tester anyway.

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