I've been having a tough time starting the car after it's warm and has sat for a while, but not cool enough to require cold start enrichment. It starts fine cold, and starts fine after the combustion chambers are warmed up and turned off and started again. I hooked up a gauge and my fuel pressure drops over time. I have braided teflon fuel lines, so I cannot just pinch them to see if it's the regulator or the check valve in the pump. Either way, neither of those two would cause starting issues. If your pump primes when you turn on the ignition, then your fuel pump relay is good, and you WILL have pressure while you are cranking. Even if the relay is bad, your engine will likely develop the 4 psi of oil pressure during cranking that it takes to close the fuel pump switch, turning on the pump. I deleted my cold start injector. I am still losing pressure and still have the starting issue. The injectors still flow a lot of fuel on startup, and on purpose. I don't know why they ever went with a 9th injector. The logic is there to know when it's cranking, and the computer obviously still enriches a little. Okay, on with my point...

If your engine doesn't fire right away, try this. Hold down the gas pedal (80% or more TPS reading) while cranking so the ECU will inject barely any fuel (a target ratio of 20:1). This is called "clear flood mode." If injectors are leaking, there is already a large amount of fuel in 1 or more cylinders. If it fires right up, your problem is a leaking injector. The problem is that without clearing the flood, it's injecting more fuel, and it takes a few seconds to pump out the excess fuel.

Is my thinking correct? I don't have injectors that have the clips to hold it to the rail, so I can't test it that way. As mentioned I can't pinch my lines, and even so, an FPR or check valve that doesn't hold pressure is no problem.

 

Yes that is largely true, although if the FPR leaks fuel into the vacuum line, the same thing will happen.


Why not just get a set of clips and put them back so you can test them the usual way?

 

Because the injectors (Bosch design 3) don't take the clips. I have no way of testing them, except maybe to take them off and create some kind of jig to hook them up one at a time to a compressed air supply. I would think that an FPR that leaks gas into the vacuum line would not even correctly regulate fuel pressure. Mine is exactly where it should be...43.5 psi (3 bar).

 

Question 1: How long does it take for the fuel pressure to drop after shut down?

Question 2: When the engine is up to operating temperature, do you think the CTS might be telling the ECM the coolant is still "cold" on restart?

Here's a crazy thought if you can't lock the injectors to the rail:

1. Run the engine and shut it off (maybe not necessary to do this step).
2. Pull the valve covers.
3. For the cylinders where the intake valves aren't opened, crank down the rocker nuts to open the valves, but don't bind the springs (you might want to write down how many turns of the nuts for when you put them back where they were).
4. Turn the key to RUN to pressurize the fuel system but don't crank the engine. Do this a few times.
5. Pull the plugs to see which ones are wet.

If you ever need to "pinch" the fuel lines, find some plugs and caps and use them instead of Vise-Grips.

 

1. I don't know. I don't watch paint dry. It shouldn't drop at all. If it was the FPR, it would either be leaking down through the return, which is harmless, or leaking out through the diaphragm, which it's not doing. I sat there for a good 10 minutes with the fuel relay jumpered and the vacuum line removed from the FPR.
2. No. I have no fuel consumption problems. A coolant temperature sensor reporting too cold would give me terrible mileage. This point here is negated by the fact that when it won't start, it will fire right up with the "clear flood mode."

I'm not doing all that. That's more work than just pulling the injectors, putting in my old ones, and getting a refund or whatever for these Bosches that I bought. I vowed when I changed my valve stem seals that the next time I need to do something to my spark plugs, I will pay someone to do it.

The problem is intermittent, anyway. Doing any large amount of work on it to do a test is absurd, and in my book is equal to just throwing parts at it. Time is money.

 

Yes, they do. I have them on every set of those I have. They go right back on just like they did on the older style.


Put em back on there; while not "necessary" for proper operation, they're an "assembly fixture" to allow the factory to put the injectors and rail together and handle em that way, they're REAL handy to have on, for the same reason, after the car leaves the factory. For testing, for example.

 

To check for leaky injectors run them for a minute or two. Pull the plugs, if you have a wet cylinder then you more than likely have a leaky injector.

 

These injectors don't take the clips well. They weren't designed for them. They had to be forced in because the body of the injector is slightly too large, and even then, the injectors pushed out to the point of leaking (towards the end). There is no slit in these injectors. The thicker part near the o-ring is also beveled. Irregardless, I found a couple were getting wet at the bottom while running the pump.

I already said I'm not touching the plugs. Too much of a PITA. I'd rather rip apart the intake system to directly see an injector leaking.

After I tested this, my fuel pressure no longer holds (drops to zero in seconds) and the fuel pressure is slightly higher.

I guess I will just buy a new set and a new FPR diaphragm. Should I get a brand new set, or rebuilt? These set I bought had claims of being rebuilt and tested, blah blah blah, and they leaked. I can't be spending this much time and money on something so minor, and I don't have a backup set to throw in, should something happen.

Every time I take apart a saginaw fitting, I need to put a new o-ring on it, irregardless of the fact that I put oil on them when assembling the fitting. Does anyone sell a large bulk set of those viton o-rings? Individual packets are too expensive.