Fuel injection questions Options

[andreic]

Hello,

about 1500 miles and 1 year ago I rebuilt my 1.8L engine (I built it up to 1.9L). When I did this I also went through the fuel injection system, original L-Jet. It is working generally well. But there a few things I still gripe about and which I would like to address. If anyone could suggest where the trouble is, I would be grateful.

1) If I try to start the car after it has sat for 1-2 days (or longer), it does not start immediately. It is as if the fuel system loses pressure, and it takes a few seconds of cranking to build up fuel pressure. Where could I be losing pressure, if I am? And where would air enter the system? If I try to start the car within 2-3 hours after running it, it starts right away.

2) When starting the car cold, it runs very poorly. The RPM is very low, and even though it will (barely) idle very low without my foot on the gas, it feels as if I need to keep my foot on the gas pedal. Driving it just 2-3 blocks it starts running fine. Could it be that my AAR is faulty? How can one diagnose that without pulling the whole injection system? (The AAR is in a pretty difficult position to take out.)

3) My idle speed is not steady. As it is currently set up, after the car warms up a bit (say after driving 4-5 blocks) it will show about 1200-1300 RPM on the tach, and it will stay that way for the first 30-40 minutes of driving. But then as the engine really warms up, after 40 minutes-1 hour, then finally the idle drops to where it should be, 900-1000 RPM. If on the other hand I adjust the higher idle (the one now at 1200 RPM) to be at 900-1000, then after 1 hour of driving the idle will drop to 5-600 RPM, and I start getting the low oil pressure light to come on at idle. Any idea what could be slowly lowering my idle as the engine warms up?

4) I only get about 18-19 MPG fuel economy in semi-spirited mixed driving (1/2 city, 1/2 highway). Is this normal? I would have expected about 25 MPG, so I am wondering if something is not making my engine run too rich.

Any suggestions will be highly appreciated. Thanks, Andrei.

[IronHillRestorations]

Try turning the key on for a couple seconds, then turning it off; do this 3 or 4 times. This will turn the fuel pump on and help pressurize the fuel system. It could be that your fuel pump is nearing the end of it's service life.

I haven't had a AFC injection system in a while, Clay Perrine is very good with those systems IIRC.

I'd look for vacuum leaks; cracked intake boots or bad vacuum hose. Sounds like it's getting excessive air which is making the system run rich.

Get it warmed up to where it will idle as good as possible, then spray some carb cleaner around any suspected air leak. If the engine rpm drops then that's where your vacuum leak is.

[timothy_nd28]

Try turning the key on for a couple seconds, then turning it off; do this 3 or 4 times. This will turn the fuel pump on and help pressurize the fuel system. It could be that your fuel pump is nearing the end of it's service life.

This has nothing to do with the fuel pump

I'd look for vacuum leaks; cracked intake boots or bad vacuum hose. Sounds like it's getting excessive air which is making the system run rich.

Vacuum leaks would make his car run lean not rich

Get it warmed up to where it will idle as good as possible, then spray some carb cleaner around any suspected air leak. If the engine rpm drops then that's where your vacuum leak is.

While I don't disagree with this statement, it is very important for a Ljet system to be free of any vacuum leaks. So, verify the system has no vacuum leaks, also verify valve lash and timing. Once this has been done, minor adjustments will be needed to the air flow meter since you changed the engine displacement. It is an absolute must in having a air fuel ratio gauge before making any AFM adjustments