On my stock '88 5.0, I'm getting a little bit of hesitation on hard acceleration and I just put a fuel pressure gauge on the shrader valve on the rail. At idle, I'm getting 30 psi with the vac line on, and 40 psi with the line off. When I rev it to 4000 rpm's (with the vac line back on), the fuel pressure moves up to about 33-35 psi. Should it be higher than this? Also, when I tuen the car off, the psi immediately goes to 0. Does it sound like a bad pump or fpr, or both?
Fuel Pressure - Hesitation
- Thread starter TurkeyLeg
- Start date
ShortThrow50
Member
Last I remember it does go to go to zero with the car off. I dont know what the psi does under accel. I never really looked
I have mine set or 39 psig with the vacuum line disconnected and it will go to 39 psig when I am in the throttle. It sits at about 31 or 32 at idle. At half throttle it will hit 36 or so. Sounds like you have a tired pump or bad regulator or blocked fuel filter.
Darren
Darren
PUNISHER RACING
Active Member
Aero hit it, you should have 42 lbs with the vac off and it should fall to 38 with it back on. Start with the filter its cheapest.
As I recall, spec is anything over 30 PSIG is acceptable. Then stock, WOT pressure is about 38 PSI.
Your observation about the 4K RPM situation does not have enough info. We'd need to know how much manifold vac was present during this time. The fuel pressure regulator works off the manifold vacuum signal.
Good luck.
Your observation about the 4K RPM situation does not have enough info. We'd need to know how much manifold vac was present during this time. The fuel pressure regulator works off the manifold vacuum signal.
Good luck.
Good call HISSIN50! A vacuum check only requires a gage and a buddy or a long hose from the manifold to the driver's seat. This is a pretty cheap check too.
One other thing I forgot is the smock or prefilter on the inlet of the fuel pump. If you drop the tank to check this I would say just go ahead and buy a new prefilter and pump if you have the cash as this is not one of those tasks you like to do on a weekly basis. I would suggest either a 190 0r 255 lph unit as this will get you through a bunch of mods. I had the 255 lph unit on my car waaay before any mods and it was not a problem setting the fuel pressure. I would also suggest a Walbro unit as you can find them for a good price and they are damn reliable.
Darren
One other thing I forgot is the smock or prefilter on the inlet of the fuel pump. If you drop the tank to check this I would say just go ahead and buy a new prefilter and pump if you have the cash as this is not one of those tasks you like to do on a weekly basis. I would suggest either a 190 0r 255 lph unit as this will get you through a bunch of mods. I had the 255 lph unit on my car waaay before any mods and it was not a problem setting the fuel pressure. I would also suggest a Walbro unit as you can find them for a good price and they are damn reliable.
Darren
The stock one should suffice for you. The puter will dial back injector pulsewidth accordingly (in case your FP goes up a pound or two from the new pump).
To each is their own. I would get an adjustible regulator but that is just me. If you do I have run three different ones now and I like the Kirban unit the best.
Darren
Darren
