i know i have to put a fuel gauge on and watch. i want to know how long should pressure remain the same until it starts to drop?i am having a hard start when hot..my first test held for approx one half hour ehen i came back it dropped at least ten pounds.. what is acceptable? before replacing injectors?

 

that sounds questionable.

I will be honest, the early Bosch injectors are known to leak. I would replace with the Ford Motorsports injectors... I think you need the 22# units, but I don't exactly know for the L98.

 

Here's a test procedure I copied from this site a long time ago. I don't know who the author is:

Ron

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1. Install a fuel pressure gage on the fuel rail Schrader valve, (such as that supplied in the injector plugging test kit).

2. Pressurize the system by cycling the key on for a few seconds.
3. Turn the key off, and time the pressure reduction on the gage. (Initial pressure should be approximately 40 pounds per square inch (PSI), note the time it takes for a pressure drop of twenty PSI to occur. If the time exceeds twenty minutes, check valve, regulator, and fuel injectors are free of excessive leakage and the Service Manual should be referred to for other causes of long cranks.)

4. If the system pressure is reduced by 20 PSI or more in 20 minutes or less, then one or more of the three components mentioned are suspect.

5. Turn the key on for a few seconds to re-pressurize the system and clamp the rubber portion of the supply line closed using a pair of vise grips and a shop towel (to protect the fuel line from damage by the vise grips.)

6. Turn the key off, and again note the time it takes for a reduction of twenty PSI. If the time is a lot longer than the time noted in step 3, then replacement of the fuel pump is indicated.
7. If the times are similar, then repeat steps 5 and 6, only this time clamp the return line instead of the supply line. Once again note the time it takes for a twenty-PSI pressure drop. If the time is a lot longer than previously, a faulty pressure regulator is indicated. If the time remains shorter than twenty minutes, leaking injectors are suspected. To confirm that there are leaking injectors, raise the fuel rail slightly out of the inlet manifold without disconnecting any fuel lines and place a small napkin or piece of paper under each injector. Pressurize the system by cycling the key on for a few seconds then turn the key off and allow to sit for about 10 minutes. If a leaking injector is indicated by one or more drops of fuel on any of the napkins, all eight injectors should be replaced with service injector, P/N 10108481.

 

cleaners help any??? maybe a little??

 

I just replaced my original injectors with Ford 22# brand new takeoffs from 5.0 Motorsports. Cost $98.00 for the set. They have the pink tops. My original ones were actually rusty on the tops, ( ) & a couple of them were crumbling. Haven`t started it up yet. Still having fun installing valve seals first.

 

The 85 injectors are supposed to be the best ones according to Rich @ cruizin performance. They're capable of flowing more than the other years and are more reliable.

I checked for leaks by dissasssembling the entire TPI, raising the fuel rail above the intake base (wiith the fuel lines still hooked up), put paper under all of the injectors and primed the rail.

Extensive yeah, but it worked.

 

 

I've even seen this listed as the procedure in the GM Manual.

Jake