m20 starting problem

[mr.vang]

it will only start with starting fluid but will not hold idle once it is started. it will stall if you don't press the gas pedal. i have been searching the web with no luck. the fuel pump is new and working fine. all fuses checked. i'm suspecting its the fuel pressure regulator since it starts with starting fluid. any help will be wonderful.

[jlevie]

Check the fuel rail pressure to see if the FPR & pump is working properly. But my guess on the cause would be intake leaks. A smoke test will find them.

[603Racing]

Check the fuel rail pressure to see if the FPR & pump is working properly. But my guess on the cause would be intake leaks. A smoke test will find them.

]

+1 on this.

Other cheap/free tests:

You can do a noid light test on the injectors to see if they are firing. Fuel pressure check and noid light test are both easy and very cheap (or free) to do and can provide great troubleshooting information.

You can also pull the fuel line after the FPR (and put it into a container to catch fuel) to see if fuel is moving through the system. This is another easy and free test to see if you're getting volume. Doesn't provide much info other than yes/no you have volume. Just remember, correct volume doesn't necessarily mean correct pressure.

Also also, you can pull the vacuum line that runs from the intake to the FPR. If it has fuel in it then the FPR is likely bad.

[Chriskbmx]

also don't forget your fuel filter!

[mr.vang]

also don't forget your fuel filter!

Fuel filter is new, I forgot to mention that.

[mr.vang]

]

+1 on this.

Other cheap/free tests:

You can do a noid light test on the injectors to see if they are firing. Fuel pressure check and noid light test are both easy and very cheap (or free) to do and can provide great troubleshooting information.

You can also pull the fuel line after the FPR (and put it into a container to catch fuel) to see if fuel is moving through the system. This is another easy and free test to see if you're getting volume. Doesn't provide much info other than yes/no you have volume. Just remember, correct volume doesn't necessarily mean correct pressure.

Also also, you can pull the vacuum line that runs from the intake to the FPR. If it has fuel in it then the FPR is likely bad.

I'll have to look into the noid light test as I have no clue what it is. Yesterday I pulled a fuel line and fuel was coming out when the car is cranked. Thanks

[mr.vang]

I just pulled the vacuum line you mentioned and its bone dry. So the fpr is good then

[603Racing]

I just pulled the vacuum line you mentioned and its bone dry. So the fpr is good then

That doesn't guarantee the FPR is good, but it's a good thing that it's dry.

It's also good that you have fuel volume, but again, it doesn't mean you have good pressure.

Noid lights can be rented from most auto parts stores. You connect them to the individual fuel injector connectors. The noid light should light up when the signal is sent to the injector. You can google it, lot's of info and videos out there.

[mr.vang]

update: so i got around to do the fuel pressure test and its at 0lbs. i'm leaning toward the fpr since the fuel pump is new. when i remove the return fuel line from the fpr, there is no fuel in it but when i unplug the fpr from the fuel rail, fuel splash out. any thoughts guys?

[jlevie]

That could be the FPR, or it could be that the pump isn't running when the engine is turning.

[mr.vang]

That could be the FPR, or it could be that the pump isn't running when the engine is turning.

the fuel pump buzz when the car is cranking. other than that, there is no noise on the "on" position. can a bad fuel pump relay cause no fuel pressure?

[jlevie]

The fuel pump only runs when the DME sees timing data from a rotating engine.

Sudden thought... Where did you measure the fuel pressure? The measurement must be done by tee'ing in the pressure gauge to the hose that connects directly to the fuel rail.

[Kozworth]

A bad relay or broken fuse 11 7.5amp fuse can cause an open. You can bypass the fuel pump relay by putting a jumper wire or paper clip on relay terminals 87 and 30.

[mr.vang]

The fuel pump only runs when the DME sees timing data from a rotating engine.

Sudden thought... Where did you measure the fuel pressure? The measurement must be done by tee'ing in the pressure gauge to the hose that connects directly to the fuel rail.

i know it has timing data because it has spark. i put a tee between the feed line ad the fuel rail. i also jump the fuel pump relay as mentioned above and still no luck. the fpr and the return line are dry. could it be that it is stuck closed or the fuel pump is not putting enough pressure to open it?

[jlevie]

Zero pressure at the rail supply and a dry return line from the FPR when the engine is cranking or the fuel pump relay is jumpered says that; a) the pump isn't getting power, b) there is an obstruction in the supply line, c) the pump is bad.

The way the system works is that the pump supplies more fuel than the injectors can use and at a higher pressure than the FPR's rating. The FPR bleeds off the excess pressure to result in the rail always being at correct pressure.