I am seeing conflicting information on the internet on whether the TPI system was supposed to hold a steady pressure after shutting the car off, or if slowly losing pressure over time was fine (or in some cases, instant pressure loss).

The TBI unit I am replacing drops from 14psi to 0 after a few seconds of being primed or ignition off. On this TPI, engine off and bypassing the relay for a few seconds, i get it up to the TBI pump's 14 psi, it hangs out at 14 for hours. So if this is normal, and I get that new pump in there, i should be at 50 psi, even with key off?

 

It is normal for the system to hold pressure for a long time. In fact holding pressure is a good indication that the check valve in the pump is working, the seat on the regulator is not leaking, the diaphragm is not leaking, and the injectors are not leaking. So it's a good thing! A slow leakdown is acceptable with the TPI, but immediate leaking down indicates an issue.

 

Got it. Im used to watching TBI melt to 0 after a few seconds like it gives life up. thanks.

 

I have an EP381 installed now. I believe its a 60psi, and Im getting 45 at the rail, so I assume that's the regulator doing its job. I see the pressure immediately drop after the pump shuts off though. There are no fuel leaks that I see.


Edit - it appears thirdgen tries to embed the flickr video as a flash object, when crome and firefox has discontinued support for that. i tried just using a link to it but for some reason the website keeps trying to load it up as a video.

 

I took out the spark plugs and there was some serious gas all over half of the plugs. So, whats up with that.

 

All on one side of the engine or both? Is the engine running or you still getting it set up? If it's all on one side I'd ohm the ground side of the injector harness and see if it's causing the injectors to be engaged when they shouldn't be.

 

All plugs were black, and if I remember, plugs 1, 3, 7, 4, and 8 were soaked.
Everything is physically set up. I am just at the point of turning the key and burning chips. Although now it seems I'm back to turning key and removing spark plugs lol. Ill check the resistance of the injectors tomorrow. I thought I read somewhere that if they are not around 15 that they could be stuck open, or something like that.
What's really interesting, is my last test today before i shut everything down for the night is i noticed the fuel pressure gauge jump to 40psi when I was cranking. The fuel relay wasnt even plugged in. I was just wanting to check for spark again on each cylinder, but glanced over at the gauge and noticed that. How does that happen? The pump hasnt even been on in several days and I thought I emptied the rail completely via the gauge release. When I saw this tonight I thought this might be more than just a spark issue but more of fuel delivery as well.

 

If you have the standard 3-prong oil pressure switch it turns on the fuel pump when it reaches 5-10 psi of oil pressure. It's wired in parallel to the fuel pump relay. You can always clamp the return and feed lines after priming and see if it bleeds down. If it bleeds down with both lines clamped then you have leaking injectors.

 

I didnt know about the parallel wiring. If that was the case, once the truck starts, if I were to pull the relay, the oil sending unit would still keep the fuel pump going?

 

Yep. That's correct. I've actually done that, when I was testing some fuel pressure fluctuation I had the relay replaced with a switch. Once it was running, flipping the switch did nothing since the oil pressure switch was already engaged.

 

I cleaned up all plugs and gave it another shot and get the same results. The injectors ohm tests are at 15.5 or so.
I noticed while cranking tho, that on the timing light, the cylinder i was on (which happened to be 8 I believe) would flicker, but about every 5th rotation. I hooked a spark tester up to it, cranked again, and it seemed to be a little dim. But still there.
One thing I didnt mention is that I moved the coil from the drivers side to the passenger. That required extending the pink/white wire. According to the schematic, pink goes to the ignition switch (which i am getting a good 12v signal on with key on) and white to tach (same).