'96-2001 hard start

quote "a hard start, no start, rough idle can be fixed by replacing the fuel tank fill pipe assembly and cleaning the SCPI poppet valves." From a lemonaid book.
Anybody know about / done this?
I'm looking at replacing the pump, so I guess I could inspect the fuel fill pipe, (but what to look for?).
And I don't have a clue what "SCPI" translates to in English. (and it's spelt correctly)
Any help would be appreciated.

I haven't heard of doing anything to the fill pipe, to remedy any problems before. I would like more info about this.

SCPI- Sequential Central Port Injection
AKA:
CSFI- Central Sequential Fuel Injection
CSEFI- Central Sequential Electronic Fuel Injection
SCFI- Sequential Central Fuel Injection
CSPI- Central Sequential Port Injection

SCPI is the type of injection system you have (96+) it has six centrally located injectors with lines going to each cylinder. The fuel is introduced in to the cylinder through a poppet valve in a sequential order, these valves can become clogged and cause performance problems.

Don't confuse this system with the 95- CPI (Central Port Injection) which is a "batch fire" system. It has a single centrally located injector that sends fuel to all cylinders at the same time, through six individual lines and poppet valves.

Thanks
My manual listed the injection as "SMPI" Sequential Multi-Port Injection. I guess i need to get a bit more creative in my translations.
But that's all the quote said about the fill pipe. I'm guessing maybe something to do with pressure / vacuum in the tank. I'm going to vent the tank next time I start it to see what I get.

SMPI is a different (less common) system than the ones mentioned above

SMPI is a different (less common) system than the ones mentioned above
Let me expand on this a little:
SMPI is usually used to refer to the type of injection on certain 4 cylinders.
If you have a 4.3L and it is listed as the type of injection you have. Then it will be SCPI, but it is an unusual way to refer to it.

Ok, I have a Haynes manual, which covers both the 4 and 6 cylinder engines. I'll have to do a bit more homework.
I'm not too suspecious of the injectors. I think the tank is ok, but I have to get under and check the electical supply to the pump, to make sure it's got 12 volts with some amps behind it, but I think i'm looking at replacing the pump.
Thanks again for the info

This symptom leads be to believe it might be the fuel pump relay. If the relay is defective, the engine will be hard to start. It will fire when the oil pressure switch closes a contact that also powers the fuel pump.

Before you drop the tank, swap the fuel pump relay with the AC one. If that cures the problem you know the relay is defective. Good luck

If your check engine light is on, go to AutoZone and they will read the codes for free. Don't listen to their uneducated BS, just write the codes down and comeback and post them.

It is true that the oil pressure switch will bypass the fuel pump relay and supply power to the pump. When the engine oil pressure reaches 4psi the switch will close, this would require an extended start time. Once the engine starts there won't be any drivability problems.

Before you replace the pump you should check a couple things.

1) Check your battery voltage, a battery that is reaching the end of it's life won't have the power that it once had. A battery that can't produce the power that it should will not be able to turn the starter and supply enough voltage to the pump for a quick start. This is usually more noticable on cold mornings.

2) Check the fuel pressure: (Below are the actual numbers you should look for, the Haynes and Chilton manuals have the wrong specs.)

When you turn the key on, the pump runs for 2 seconds. While the pump is running the pressure should be 60-66psi (either during the 2 second prime or while keeping it running with a scan tool) This tells you that the pump is operating within spec.


When the pump primes and shuts off (engine still off) the pressure should hold between 55-60psi. This tells you that:

1) the fuel reached sufficient pressure to start the engine ( requires 54psi min. to open poppets)

2) there is not a significant loss of pressure, which would indicate one of the following:
-a) leaking fuel injectors
-b) damaged injector o-rings
-c) leaking pressure regulator
-d) damaged or split fuel pulsator
-e) leaking check valve
-f) leaking fuel lines


With the engine running the pressure should drop 3-10psi depending on engine speed due to vacuum on the regulator. This tell you that the regulator is operating properly, however it does not rule out the regulator leaking fuel.

If the pressure does not fall within specs, it could indicate a bad pump or a leak within the system.

If the fuel pressure does fall within the above specs, then we can move on to checking the ignition system.

About the dirty poppets, if you add a bottle of Techron fuel treatment to your gas occasionally you shouldn't have any problems. If they are clogged they will cause a rough idle, poor accelleration, and if clogged bad enough they will cause misfires.

Good advice.
I should say that if I drive the van every day, it works fine, but as a 2nd vehicle, if it sits a week, it's hard starting.
Regulator: from the above, I think the regulator pressure drop is ok.
Relay: I can hear the pump run for the 2 seconds, before starting. I used to get a good start by "priming", cycling the ignition key a few times to get the pressure up, but that's not working well now.
Injectors: I believe they're ok, as the van runs well after starting, and gets good mileage, approx 24 mpg for my "average" driving.
Now that it's warm out, I was going to check the voltage under load at the pump, to make sure all the connectors on the way to the pump are ok. I've read some articles about high resistance fuse links, bad grounds, etc.
Fuel pressure: can i use a tire guage? Or do I need to go and buy the right tool?
Thanks guys

You will need to use a fuel pressure guage. Most AutoZones will have them as loaner tools (give them a deposit, use it for three days, return it and get your money back.)

I borrowwed a pressure guage.
I jumped the fuel pump relay. The pump sounds like it has a dirty commutator, draws about 4 amps to start, and slowly raises to about 7 amps after about 15 seconds, and sounds good. The pump ground wire is good.The pressure guage gets to 59 lbs, which the Haynes manual says is in spec, the pre-'96 needs higher it says. At idle, it runs well, and I get 52 psi. "Blipping" the throttle shows a momentary rise to about 61 psi. Turn engine off, pressure goes to 49, and after about 6 minutes, it's about 44 psi.
The battery is a little tired,but cranks very well, and the lights run no problem. I measured 12.4 volts after sitting for 2 days, and it wouldn't start. (but cranks fine).Your input would be appreciated

Ok. I've eliminated the battery. It was 12.7 (float), i put the charger on for 2 hours, (minimum draw), and it wouldn't start.
A GM dealer told me the 59 lbs i had is low. (thanks Blazee)
So I'm off to get a pump. I hope that does it. The GM rep said they'd never had to replace a regulator.