So I posted yesterday on a group on facebook that I installed a new chip for my 1992 tbi to 92 tpi conversion. I had no spark and no fuel pressure. Today I have spark but still don't have fuel pressure. I checked the pressure at the shrader valve and at the rubber fuel lines. I will try to test the fuel pressure today just before the fuel filter and check the ICM. I am attaching a video of what my car is doing to and hopefully someone will be able to tell me what it is. thanks


here is 1 suggestion:
Check your wiring on your sender, pump and sender/pump ground

Is there anything else I can check before I drop the tank?

www.youtube.com/watch?v=k8ZSsM-3Hak

 

You are switching to TPI from TBI? TBI fuel pump is low pressure (~15 psi) and TPI requires high pressure pump (~50 psi), so if you haven't dropped the tank and changed the pump already, you will have to. hth

 

Sorry I forgot to mention this is a new Walbro 255 pump.

 

So I tested the fuel pressure right before the fuel filter and still have no pressure. I dropped the tank and looked at my wiring on my sender and pump and everything looks fine. The hose is securely fastened on the pump and sender line. Still need to check the ICM but I'm not sure where to go from here.


Is it possible the rubber fuel lines are installed incorrectly? I put the small hose to the small metal line and the bigger 1 to the bigger fuel line. Plenty of gas still in the tank.


Is there anything I need to repin at the ecm or the drivers side firewall connector since going from tbi to tpi?

 

Need to figure out what is not getting 12volts and where. start at the fuel pump and work your way up to the front.

 

Can you hear the pump prime when you turn the ignition on?

 

Yes. Pump primes, I get fuel at the shrader valve, and rubber fuel lines but it doesn't read any pressure. Funny thing is when I turn the key off, the pump whines for about 20 seconds and the engine sounds like fuel is running back to the tank.

 

OK. So, the pump runs and you get gas at the shrader valve, but no pressure. You didn't by chance wire the pump backwards? Just a thought.

 

Just re-read complete post. You do not need to re-pin anything at the ecm. The large line should be your pressure side fuel to the fuel rail and the smaller line should be the return from the pressure regulator. You could block the return line and see if the pump builds pressure to eliminate the regulator as a problem. HTH

 

I hope not lol. from what it looks like there is only 1 way the connectors will connect to the fuel pump and fuel sender. Unless I missed something I pretty sure they are connected correctly.

 

Have you check the FPR yet? You'll have to pull your plenum off unless you can figure out a way to do it while leaving it on. I would check that and make sure the rubber diaphragm isn't cracked anywhere.

 

I did a test by pinching off the return line and it didn't make any difference on the fuel pressure. I have a couple more fpr's that I could swap out. I think it may be a wiring issue. I messed with the grounds yesterday and when I connected them back up, now my fuel pump doesn't turn off when the key is off. I have to disconnect the battery.

 

What kind of fuel PSI gauge are you using? Do you have to remove the schradervalve or does it have a center pin to open it?
Sounds like that's your problem.
You have fuel psi, just not through the valve to the gauge.

 

I'm using a fuel pressure tester from autozone. I've tested it at the shrader valve and rubber fuel lines with the same results.

 

So i tried starting the car and when I turned the key off, I pulled the oil pressure switch connector and the noise from the fuel pump and engine bay stopped. As soon as I plugged it back in, it started making noise. It's a new ops so either I got a bad one or the fuel pump/ops wiring circuit is what's wrong. What do you guys think?

 

Regardless of the ops, if the pump does truly run, you should build pressure. If you pinched off the return line, you should see over 50 psi. You changed the fuel pump out for a Walbro 255. Didn't you have to connect the pump inside the tank to the pigtails on the sending unit? Unless the pump is defective, I don't see how it can run but not build pressure.

 

sounds like a new fuel psi gauge/tester is needed.

 

I used this same pressure tester on my son's truck a couple of weeks ago and it worked fine then.

 

Wonder how many people used it or broke it between then?

 

I never took it back because I knew I would need it for my car. I think I am going to drop the tank again and install a used fuel pump that I have laying around.

 

So I put in another fuel pump and it did the exact same thing. No fuel pressure and the same noise after the key is off. Tried a different FPR and got the same results. There is nothing in my fuel lines and I replaced the fuel filter. Could it be something in my wiring harness? I did look a the ECM and there were 2 connectors that were c and d instead of having an e and f so i'm assuming my harness is not 100% factory. The wires for the Fuel injectosrs were not the factory colors that I had in my manual.

 

You keep asking about the wiring. Nobody can say what you have or don't have, we are not there. You say the fuel pump "runs" when you turn the key on. Are you sure? Tackle one problem at a time. Make sure you have voltage at the pump, then be sure the pump is running. The car was originally a TBI so the wiring to the pump should be the same. If you just removed the TBI pump and replaced it with the Walbro 255, the Walbro should also run. If the pump is in fact running, try reversing the two wires at the connector and see what happens. Can't hurt!

 

My fuel pump comes on and primes for 2 seconds. It also keeps whining for about 10 seconds after I turn the key off.


I did not repin my TBI harness. I bought 1 on here that was from a 91 tpi Camaro. I was missing a few wires so I had to add the them and pin them to connectors going into the ecm. When I unplug or wiggle the OPS wire and the noise in the engine bay goes off, that's why I am asking if my wiring harness could be jacked up

 

UNhook the feed line an stick it in a tank and hit the key. if the pump is running fuel should come out. (unless its somehow wired backwards).
The pump stays on with key off until the oil psi drops out, that's normal.

 

I unhooked the supply line at the rubber fuel lines and watched the fuel come out. didn't seem to come out very fast. Any way I disconnected the fuel pump relay and jumpered the 12v to the grey wire that goes to the fuel pump to run the fuel pump and still no pressure. Hooked all that back up and for some odd reason I now have fuel pressure. It goes up to 42 or so but still wont start. Not sure how all of sudden I have fuel pressure now but i'll take it. It seems to lose pressure fairly fast though. I did the trick to pinch the return line and the pressure didn't go up. Here is a vid of the gas coming out of the fuel line.

 

Voodoo

 

LOL, it was something.

 

faulty wiring / dirty connectors / poor grounds

or any combination of these three

 

So now it turns out I need a new IAC and TPS because my TB is off of an 87 hooked to a 92 harness and the sensors have different part numbers. I only assumed these sensors were the same. Guess I need to spend more money

 

TPS is adjustable vs non adjustable- they work the same.
Idle control motors work the same.

 

Thanks TTOP.

 

I just wanted to follow up and close this thread.


I'm really not sure what the problem was with me not getting any fuel pressure. I wish I knew to help someone else out but I didn't really remedy the issue it just kind of fixed itself.


The problem with my car not starting was the distributor was 180 out. I moved all of the spark plugs and turned the key and bam, it started. Scared the crap out of me actually :-)


Thanks to everyone for their suggestions