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Help with fuel injection settings

1K views 11 replies 4 participants last post by  Siggy_Freud 
#1 ·
I have a 305 sb chevy 5.0 with fuel injection and I need to know If anybody knows the factory settings or how to adjust the fuel injection.The engine is an 89.It takes along time to start and the guy i bought it from messed with the settings.Let me know.thanks
 
#3 ·
If it's TPI, the fuel pressure should be set to 43.5 psi from the factory with the engine running and the vacuum line unplugged from the fuel pressure regulator. And of course the disconnected vacuum line needs to be plugged to prevent a vacuum leak.

If fuel pressure is okay, I would suspect a bad fuel pump relay. The fuel pump relay primes the pressure when you first turn the key, and also powers the pump when running. However, the oil pressure switch will also power the fuel pump as a means of a backup system.

So if the relay is bad, the long cranking can be due to the time it takes for oil pressure to build, closing the circuit and powering the pump.

Ed www.edgesz28.com
 
#7 ·
Need more information

EazyDuzIt102 said:
Oh and when the engine is pretty much warmed up it sounds like it wants to die are starts stalling when i give it alot of gas at once.I cant even brake torqe it.
The first thing you need to do is identify exactly what you have. Is it TPI or TBI? You also need to give us the "settings" that the other guy messed with. You also need to find out what your fuel pressure is set at. And, a fuel pressure gauge will help identify if any injector(s) is leaking.

Is it throwing any codes? If so, what?

That stalling can be any number of things [fuel pressure, IAC, TPS, EGR, timing]. It could be nothing more than it needs a major tune-up (especially plugs, wire and cap & rotor). When was the last time the fuel filter was changed?

As far as checking the relay, someone else will have to answer that. But if you have electric fans, there should be three relays just above the brake booster. When my fuel pump relay went bad, I simply switched the relay using the harness plugs. And a relay for that car should be less than $20.


Give us more information, or anything suggested here is nothing more than an educated guess. Ed
 
#8 ·
Generally, you should be able to hear if the fuel pump is priming for the 2 seconds when you turn the ignition on (ignition, not fully starting the engine mind you). If you cannot, a repair manual for the car has the procedure for testing the relay. It pretty much involves jumpering 12v to the post on the relay that is suppose to prime for 2 seconds. However, you'll need the book to identify the post, as well as other procedures that will help in determining the problem.
 
#10 ·
You should be able to hear it. To be sure, hook up the fuel pressure guage. If you cant see it from inside the car, have a friend look at it. Turn the ignition on. They should see the fuel pressure jump up to its normal operating range. It should hold there as well. If its not jumping up, the fuel pump relay isn't priming the system. If the fuel pressure doesn't hold after the prime, you have a leak somewhere.
 
#11 ·
EazyDuzIt102 said:
The fuel filter was changed like 2 days ago.I'll check the fuel pressure and all of the other stuff.so i will be able to hear if the fuel pump is priming when i put the key on start(but dont start it)and if i dont hear anything than its the relay??
not necessarily... if you flip the key on and dont hear anything then start with the relay. if you replace it and it still doesnt do anything then trace the wiring and see if there is a short in one of em. and if that all checks out then its your pump. also, check the fuse for the fuel pump. check to see if theres corrosion on the terminals and if there is make sure you clean em off and put a new fuse back in. good luck! :thumbup:
 
#12 ·
The pump really cant be at fault for not priming. If it wasn't going to prime it wont pump at all. The only inputs on the pump itself are power and ground. Simply put, the pump doesn't know if its priming the system or running the system. It only knows off and on.

However wiring TO the relay could be faulty.
 
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