vortec fuel injection

[drewopo]

i have a 98 chevy that i put a new creat motor into about a year or two ago now and now when u go to start it,it will jsut turn over unless u spray a little starting fluid down the intake, then will run fine all day long, i think i have the problem tracked down being with the spider injection and was wanting to know the best place to find a new one, i have already had the comp retuned by allen when i switched from the original 5.0 to the 5.7 but i was wandering if there was a better performace one that i should look for also for it, thanks for any help
drew

[RedHeartbeat]

I had the same problem on an 87 GrandAm and it turned out to be the spark module in the distributor. Your's sounds like maybe it could be the oil pressure sending unit or fuel pump to me. That or the coolant temp sensor. They seem to have that bitch cross-wired into every single engine circuit.

[drewopo]

i know i can eliminate the fuel pump and the distro as i have had to replace both of those already since put the new motor in, i'll have to check on the oil pressure sending unit or the coolent temp though, still thinking it might be in the spider inj. though , best i can remember thats the only part i really moved from the old motor to the new one, kinda sure i had replaced all sensors since i had it all apart at the time but not totally sure, and with the 190 k miles on it wouldnt be surprised

[NITROUS]

You can try swapping to the marine intake with external injectors and fuel rail. That would be your best option. Check this link out. Marine intake

If you want to stay stock, any ACDelco dealer can help you out.

[hummertech]

check your fuel pump relay, when there is oil pressure the fuel pump starts to work through the switch. install a fuel pressure gauge and check fuel pressure when cold. if it is low or none, try to crank the engine over and watch the pressure, if after it get oil pressure the fuel pressure starts to rise, keep the engine cranking until it starts (if it will). it takes way more fuel pressure to start than it does to run.

[docone882000]

I thought the pump was suppose to prime the system before you crank it over so you did not have this problem??? Every efi system I have worked with primes the system before start up with like a 5 second burst from the pump.

[hummertech]

<div class='quotetop'>QUOTE(docone882000 &#064; Nov 6 2006, 09&#58;12 PM) [snapback]72459[/snapback]</div>

I thought the pump was suppose to prime the system before you crank it over so you did not have this problem??? Every efi system I have worked with primes the system before start up with like a 5 second burst from the pump.
[/b]

that is what it should do. the pcm grounds the fuel pump relay for 2 seconds after key up to build pressure. if the fuel pump relay doesnt work that wont happen, but when oil pressure builds the secondary circuts closes and powers the fuel pump through the oil pressure switch. hear is the funny part, not all trucks will run off the oil pressure switch????? only about 1/2of them. there is no answer for it???? it must be a shitty switch. let the engine run....remove the fuel pump relay....the engine should run off the oil switch. so if your relay was bad the engine would have to crank for a long time before the fuel presure would rise high enough to start. and the 350 vortec truck engine takes a shit load of pressure to start good. like 75-90 lbs.
if you have clogged injectors it takes the higher pressure to start.

[drewopo]

thanks for the replys will be most helpfull when i finally get 10 minutes to take a look at it hopefully tongiht

[drewopo]

ok i have tried what hummertech said to try, once i started it , i pulled the fuel relay and the motor cut out after about 5 seconds, when cranking it over with my feul press. gauge it only reads about 40 lbs more or less, so does that mean the oil press switch is bad or a weak feul pump thanks for any help

[hummertech]

sounds like you have a cloged filter or bad pump, read this page from the manual.



When you turn ON the ignition switch, the Vehicle Control Module (VCM) turns ON the in-tank fuel pump. The pump remains ON as long as the engine is cranking or running and the VCM is receiving reference pulses. If there are no reference pulses, the VCM shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position or if the engine stops. The VCM will also turn ON the fuel pump for 2 seconds when the ignition is turned to the OFF position.

An electric fuel pump pumps the fuel through an in-line filter to the Central SFI unit. The pump is attached to the fuel level meter assembly inside of the fuel tank. The pump is designed to provide fuel pressure above what is needed by the fuel injectors. The pressure regulator keeps the fuel available to the injectors at a regulated pressure. Unused fuel is returned to the fuel tank by the fuel return pipe.

Diagnostic Aids
Tools Required
J 34730-E Fuel Pressure Gauge.
J 34730-1A Fuel Pressure Gauge with J 34730-250 Fuel Pressure Adapter Kit.
J 42873-1 and the J 42873-2 .
Test Description
The numbers below refer to the step numbers on the diagnostic table.

Wrap a shop towel around the fuel pressure connection to absorb any small amount of fuel leakage that may occur when installing the fuel pressure gauge. Turn ON the ignition leaving the engine OFF, the fuel pressure should be 415-455 kPa (60-66 psi) when the pump is running. This pressure is controlled by a spring pressure within the regulator assembly.

The fuel pressure that continues to fall is caused by one of the following items:

- The in-tank modular fuel sender is not holding pressure.

- The fuel pressure regulator valve is leaking.

- A Central SFI injector is leaking.

- Fuel line is leaking.

If the fuel pressure is less than 379 kPa (55 psi) at idle, it falls into the following 3 areas:

- The pressure is regulated but less than 379 kPa (55 psi).The amount of fuel reaching the injector is sufficient, but the pressure is too low. The system will run lean, hard starting cold, no start, overall poor performance, and may set a DTC. Refer to Engine Cranks but Does Not Run

- A restricted flow causing pressure drop -- Normally, a vehicle with a fuel pressure of less than 300 kPa (44 psi) at idle is inoperable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop running as the pressure begins to drop rapidly. This is most likely caused by a restricted fuel line or plugged filter.

- A leaking or contaminated pressure regulator valve or seat interface may not allow the regulated pressure to be achieved.

Notice: DO NOT allow the fuel pressure to exceed 517 kPa (75 psi). Excessive pressure may damage the fuel system.

Restricting the fuel return line allows the fuel pressure to build above regulated pressure. With the fuel pump comanded ON, the fuel pressure should rise above 455 kPa (66 psi), as the valve in the return line is partially closed.

When the engine is idling, the manifold pressure is low (high vacuum) and is applied to the fuel pressure regulator diaphragm. This will offset the spring and result in a lower fuel pressure. This idle pressure will vary somewhat depending on the barometric pressure; however, the pressure at idle should be less indicating the pressure regulator control.

If the injector(s) is not grounded, physically remove suspect injector(s) and inspect for a fuel leak while system is pressurized. If the fuel injector(s) are not leaking and fuel pressure is not holding, the fuel pressure regulator should be inspected for a slow diaphragm leak.