Help needed please!

I have a 89 IROC 5.7 TPI. What should the fuel pressure be at the Fuel Rails where the check vavle is.

While driving it was anywhere from 34-47 PSI. It would idle around 37-38 be up at 45-47 while in throttle and then sometimes drop to 34 when cruising.

It's a stock FPR but I am wondering should it be like this?

Thanks,
Ed

 

those numbers are in factory specs.

 

Someback ground for this question is I came close to over heating two weeks ago. I noticed I was running high temp 240 when I came out from the store. When I started the car it started really rough like it wasn't getting fuel or spark, as it started to crank over it fired but was really slow and then came up to idle 500rpm.

I got it home without hitting 260 temp. I have changed oil and plugs becuase I felt something wasn't right it seems to hesitate.

WHile coming home last night the car started to die like it was being flooded with fuel. Had to pull over a few times and let the car sit before starting again. if I stepped on the gas pedal it would bog down. I couldn't get over 5 MPH while in this mode. I think it might have been in the limp home mode.

Compression is 120 all the way around but the fuel pressure was very erratic. O2 sensor was white and I replaced it.

It seems like it isn't getting something like fuel or spark. Going to ohm out my wires (MSD Supers) and check my rotor and cap (Hypertech cap and Rotor only 6 months old)

 

I had a very similar problem that left me scratching my head for a while.. it was sparatic too. Some days it was fine, other days it ran like crap.

Eventually it left me stranded and on a few occasions and I'd have to leave the car for a few hours before it would start again.

Then it quit all together. Turned out being the fuel pump.

 

So, how is it behaving now? Other than the erratic fuel pressure is it running good?

 

So right now I ohm'ed my wires and they are good.

I put in a MSD Cap, Rotor and Blaster coil.

The hesitating has gotten less but the motor is rocking especially when in Nuetral or Park. You can feel the car sway side to side. I wish it was from a massive engine but it's not. It started doing this after the rough start 2 weeks ago.

 

Found some issues and wanted to report them.

Found one injector OHM'img at 8.2 and all the others were 16.5

I am going to also replace the FPR with an adjustable one.

Any recommendations on Injectors (with lbs) and an AFPR

Thanks
Ed

 

you shouldnt need anything over 30lbs

 

22# are stock on 350.

I would suggest replacing what u have as long as you check the rest of them for leaking.

If I find 3 or more bad or leaking I just replace the entire set for piece of mind and no more future hassle.

If u use a size other than 22 I would recommend changing the injector constant in the chip to account for it. It will run otherwise, but it wont be 100% correct.

later
Jeremy

 

Thanks Jeremy,

Think I might go with the Ford SVO #24 injectors. Seems that they are very good.

Don't have the money to start buy PROM equipment yet but I might see if someone here in my region has a setup that I can make it right.

The car sat for many years so parts are starting to wear fast. But I'm not giving up my third gen! Just having to learn really fast on how to fix things.

 

Update on my issue.

Replaced my injectors with some FMS (Ford Motor Sports) blue top 24#. Also installed a TPIS Adjustable Fuel Pressure Regulator. Set it at 46 and everything is running great!

Thanks for all the help everyone.

 

The fuel pressure should vary, and should be much lower at idle because it is vacuum modulated. When youre idling and pulling lots of vacuum it lowers the pressure, then as you come up in the RPMs the pressure rises.