Fuel pressure reg or gold temp sensor?

[Chells_88ix]

Hey guys, still trying to get this ix to start after replacing the head. Finally found a gauge that we could check the fuel pressure to the rail with and it is around 46 psi, so it looks like the pump is doing ok. Does this leave the FPR and maybe the one sensor at the end of the injection rail, the gold one? We did have to remove it during the install to save from taking several other parts to put something back on. Does that sensor only have one metal prong inside? That is what mine has and I cannot see where anything is broken off, just thought it was strange that there was only one metal prong for the electrical to plug into.

What other places are there to look? We replaced any hose that even looked like it was ready to crack to clean up all the vacuum issues and the only vacuum issue we can see may be a plastic elbow that fits to the right side of the throttle body. The previous owner had it held in with some red goo around the plug.

Any ideas? Many thanks!

[jlevie]

The single pin temp sensor is for the temp gauge and has nothing to do with operation of the engine. 46psi at the rail is a bit too high and might mean a bad FPR or obstruction in the fuel return line.

Do you have spark and operation of the fuel pump when franking over the engine. And are the injectors firing?

[Chells_88ix]

We have spark and the injectors appear to be firing, we checked those with the noid tester. We checked the fuel flow coming to the rail and it appears to be in line but coming out of the back of the FPR it is more like a slow dribble. You mentioned the operation of the fuel pump, if I have fuel to the rail at the correct amount and the pressure coming to the rail is good, should that not mean the pump is operating correctly?

[jlevie]

Only a slow dribble from the FPR suggests low fuel pressure in the rail or excessive pressure from a bad FPR. If the pump is running while the engine is cranking that combination would suggest a failing pump, clogged filter, or a bad FPR. Just checking for fuel flow only tells you that the pump is running, You need to check pressure to see if the the system is working properly.

[Knockenwelle]

If I remember correctly, the stock FPR has a 3 bar set point, which should be right about 46 psi without vacuum. Chells, if you're only getting a little fuel out of the regulator, it might be plugged with debris or just NFG. You have triple-checked the fuel line connections as to supply and return, yes?

[Chells_88ix]

We checked the pressure coming to the rail and it was about 46 psi and the flow when checked measured up to where it should for the supply line. We double checked the lines and only one had gas coming through and that one is the one connected to the fuel rail.

Stopped at the local pick n pull and picked up to FPR's that look close to new and thought we would try them out just to see if it would make a difference, plan to check that out tomorrow.

You have to try starting it several times before you can even pick up a hint of a gas smell. When we tried checking the return line only a dribble came out. Can I use the gauge to check the psi coming out? Will that tell me anything?

[jlevie]

When you checked the pressure to the rail did you insert a tee into the supply line so that you were seeing the regulated pressure? That is the only valid fuel pressure test.

There should be a lot more fuel flowing from the FPR than just a trickle. For a fuel system in good condition the minimum flow from the FPR is 875cc in 30 seconds and the test is done with the fuel relay jumpered, so no fuel is flowing through the injectors.

[Chells_88ix]

To check the pressure to the rail we did T the fuel pressure gauge into the supply line and that is where we got 46. Just finished swapping the FPR for the one we picked up at the pick n pull and we now have a steady flow of fuel coming from the back of the FPR but it still will not start, just sounds like it is starved for fuel and isn't getting enough to complete the crank over.

We have checked the injectors with the noid tester and according to that they were ok, so any other ideas to try out? I am not sure what you mean by the test using a fuel relay jumpered process. Thanks again, I appreciate all the help.

[Chells_88ix]

I am looking over the fuel prep system - fuel injectors on Real OEM's website and they show as part of the computer system a temperature sensor. Could a bad one of these cause the system to have starting issues? When we did the stop test the only number that came up is the one that can be pretty much anything and one of the items listed was the temperature sensor. Am I correct in assuming that if the injection system cannot read the engine is cold it would not send enough spray to start the car?

This is the first injected system we have worked on in our house as most of our toy cars are carb set up so tweaking is much easier.

[jlevie]

To check the pressure to the rail we did T the fuel pressure gauge into the supply line and that is where we got 46. Just finished swapping the FPR for the one we picked up at the pick n pull and we now have a steady flow of fuel coming from the back of the FPR but it still will not start, just sounds like it is starved for fuel and isn't getting enough to complete the crank over.

We have checked the injectors with the noid tester and according to that they were ok, so any other ideas to try out? I am not sure what you mean by the test using a fuel relay jumpered process. Thanks again, I appreciate all the help.

Have you re-checked fuel pressure with this FPR in place?

I'm suspecting a problem with the fuel pump. With the plugged up FPR in place you should have had a lot more than 46psi. Only seeing that much pressure and very little flow from the FPR tends to suggest a failing fuel pump. Now that you have flow from the FPR you need to make sure that you still have normal pressure in the rail.

To run fuel pressure and delivery tests you need the fuel pump running. While that will happen when the engine is cranking, it is much easier to run the pressure and delivery tests by jumpering the fuel pump relay to force the pump on. This and many other things are documented in the Bentley manual.

A shorted Coolant Temp Sensor (CTS) would tell the DME that the engine was hot and thus needs a leaner mixture. Assuming no short in the wiring between the DME & CTS, unplugging the CTS would make the DME think that the engine is very cold and it would then command a richer mixture. In moderate ambients 60F or above the engine will start even with a bad CTS.

An intake leak may make it impossible to start the engine because the mixture may be just way too lean.

[Chells_88ix]

Plan to recheck it tomorrow, the rain moved in and the car is outside right now as I had to put another car in the garage to change the oil. I saw the process in the Bentley that you mention, I guess I just hate sticking wires in places that might "scare" me :). We have just been cranking the car and monitoring the battery level closely. I don't think there is a short in the wiring as the loom looks to be in good order and tightly wrapped still.

I did notice something that made me wonder, the previous owner for some reason beyond me removed the AC and when I look at the water elbow diagram on RealOEM it shows a switch and another item that are not present on my elbow. I am wondering if they swapped the elbow out for a non AC car, if so I also wonder if they put the two sensors that are there in backwards since mine appear to be different than the diagram. May throw up a post and see if another ix owner will post a picture of their's for comparison.

If it doesn't start soon there may be an ix for sale, with no real rust to be seen that I have found, for a cheap price :).