5.7 vortec long crank

[Schurkey]

I don’t know the compression pressure. How do I measure that?

Buy or borrow a compression tester. Fully-charge battery. Warm-up engine. Remove all spark plugs, block throttle at least part-way open.

Screw gauge hose into each plug hole, crank engine until gauge tops-out. Generally, 4 to 6 puffs, but if the needle is still going up, keep cranking. Record readings.

Lowest pressure reading should be within some percentage of highest reading. Some folks say 25%, a smaller percentage is better.

Also could this problem be related to my hard start?

Sure. If one or more cylinders don't run, it's going to make things harder on the rest.

 

[slow_c1500]

Buy or borrow a compression tester. Fully-charge battery. Warm-up engine. Remove all spark plugs, block throttle at least part-way open.

Screw gauge hose into each plug hole, crank engine until gauge tops-out. Generally, 4 to 6 puffs, but if the needle is still going up, keep cranking. Record readings.

Lowest pressure reading should be within some percentage of highest reading. Some folks say 25%, a smaller percentage is better.


Sure. If one or more cylinders don't run, it's going to make things harder on the rest.

I looked at the cap and it looked pretty normal, clean, no corrosion. Since we already measured the fuel pressure to be low, doesn’t that mean leaky injectors/FPR are the next likely suspect? Or could it be a problem with the entire distributor? I don’t have access to a comp tester at the moment.

 

[Caman96]

I looked at the cap and it looked pretty normal, clean, no corrosion. Since we already measured the fuel pressure to be low, doesn’t that mean leaky injectors/FPR are the next likely suspect? Or could it be a problem with the entire distributor? I don’t have access to a comp tester at the moment.

Auto Parts Store loaner tool. Do you smell fuel?

 

[slow_c1500]

Auto Parts Store loaner tool. Do you smell fuel?

Yes I smell fuel on plugs 7, 6, 8, and 3. Cylinder 7 is the only one throwing a code though. The inside of the cap itself looks fine, but the cap was a bit loose due to the rear screw being stripped. I think this may be causing a weak spark which would explain my problems. I will get a repair plate to hold down the cap properly.

 

[Trucker1]

Just had same problem with my 98 Tahoe and it ended up being the spider injector. Installed new updated spider injector and my Tahoe starts instantly.

 

[slow_c1500]

Just had same problem with my 98 Tahoe and it ended up being the spider injector. Installed new updated spider injector and my Tahoe starts instantly.

The thing is that my truck already has the MPFI injectors. I am waiting on the distributor repair plate (the rear screw was stripped so the cap wasn’t secured properly) and i will let y’all know what happens.

 

[Caman96]

So I don’t necessarily mean on plugs, just in general as you crank motor or as it’s running. Definitely straighten out cap and do test with loaner tool. What brand spider did you put in?

 

[Schurkey]

I suspect you've got injector/regulator problems.

It'd be silly to rip the top off the engine before exploring other possibilities, though. So, yes, compression test, verify ignition system, and fix the distributor, etc.

If you still have driveability issues/long crank...you're probably looking at another spider/regulator, and/or fuel pump if it can't deliver appropriate pressure.

 

[slow_c1500]

The spider was an eBay special. At the time I hadn’t yet learned to only use AcDelco or Delphi parts for these trucks. As far as gas smell, i can’t really smell anything from the engine or in the cab, but the tailpipe smells a little gassy. Not sure if all these trucks are like that, though.

 

[Caman96]

The spider was an eBay special.

That’s why I asked.

Not sure if all these trucks are like that, though.

Mine doesn’t.