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bufbooth
Registered User
Hello All, I think my 91 Toyota pickup with a 22RE engine has a stuck open cold start injector. I thought my fuel pump was failing until I did a pressure test using as the cold start injector. I connected a fuel pressure gauge to the fuel line going into the cold start injector, and had 28psi (which is about normal at idle). I revved the engine up and the pressure did not go up, should have gone to 32-35psi. As the engine warmed up, the psi started dropping to 15, then 10, then down to 0. Yes zero with the engine running. I turned the engine off and let cool for 10 minutes and started back up, and psi was at 20psi. So do I have a bad cold start injector, or a bad sensor that controls it? Thanks all...

 

csi has NOTHING to do with fuel pressure.

 

There is no "sensor" that controls the line to the CSI. You're just measuring the fuel pressure at the rail, by placing your gauge on the port usually used by the CSI.

Correct fuel pressure at idle is 33-37psi (28 is too low). https://web.archive.org/web/20150116...28fuelpump.pdf When you rev the engine, the fuel pressure goes down, not up. (Why? The FPR's job is to maintain constant pressure across the injectors. When you open the throttle, the intake manifold pressure drops, so the FPR lowers the fuel pressure to follow.)

While it's possible you've got a clog right at the CSI port only, that seems a little unlikely. Unless I've completely misunderstood your test procedure, I'd try a different fuel pressure gauge.

 

If the cold start injector opens and then gets stuck open, wouldn't that cause the fuel pressure to drop since it's dumping fuel into the air intake? It's odd that the fuel pressure gauge ended up dropping to zero (even though I could still rev the engine up). I even let the engine cool back down and repeated the pressure drop. I will locate another fuel pressure gauge and try it again.

 

No. (But ...) A CSI wouldn't do much good if whenever it opens it pulls down the pressure to the injectors.

More importantly, when you said "I did a pressure test using as the cold start injector.," I assumed you used the FSM procedure (I cited the FSM). There, you disconnect the CSI and plumb the gauge into the rail where the CSI was once connected -- no CSI in the circuit.

If you're not using the FSM procedure, you might explain what you did.

 

What I did was remove the banjo bolt that secures that small metal fuel line to the cold start injector and screwed in the fuel pressure adapter bolt in its place.
. I ordered a new fuel pressure gauge, will get it on Thursday.

 

Hello All....I received the new fuel pressure gauge and hooked it up to the cold start injector and started the engine.
The gauge read 22psi and after a few minutes dropped to 20psi and held there for the next 10 minutes.
The psi did not go up nor down when I revved up the engine, and disconnecting the csi did not cause any psi change,
nor did removing the vacuum line from the fuel regulator. I was told by the past owner that he replaced the fuel pump
shortly before he sold it to me. Also, I removed the fuel pressure gauge banjo adaptor from the csi about a minute after
turning the engine off and expected fuel to spray out, but it only dripped a couple drops.
So, do I have a fuel pump issue or a fuel pressure regulator issue (that is restricting the psi and/or not keeping the psi up after engine shut off)?
Also, when I turn the key on (but do not start the engine), should the fuel pump turn on? Right now I only pressure if the engine is running.
Is the item in the Red circle the fuel pressure regulator? And what are the items in the Orange and Purple circles?
Any suggestions on brands for a fuel pump and/or Fuel Pressure Regulator?
Thanks again....

 

Turns out the 3 inch long rubber fuel line that goes from the fuel pump to the metal fuel line was off the fuel pump, the hose clamp had loosened and was off the hose, but the hose was still inline. This was also why it was hard to start after warm, since the fuel was leaking down and the cold start injector was not being triggered (cause it was not cold). I now have 32psi and starts immediately cold or warm.

 

There is no "sensor" that controls the line to the CSI. You're just measuring the fuel pressure at the rail, by placing your gauge on the port usually used by the CSI.