Car trouble :(

[anthony1707]

I just realized that I never did reply with what ended up happening with the car. I bought a used engine and 5-speed from my local l.k.q and installed it into the car, and it still did not run properly so I did do a fuel pressure test to find that it was only getting 10 p.s.i at the rail. This was strange because I had put a new fuel pump in, and I actually ended up putting an old one that I had into the car and it got the car back on the road! It was driving decently but it still has a bog at only partial throttle, and at full throttle it will rev and the car will speed up, but it feels weak- it will catch at certain points and gain more power and loose it randomly. I have replaced the v.a.f, checked for vacuum leaks, and checked ignition timing. The car seems to run better with more than the stock 8 degrees advance, and the car runs far better with the coolant temperature sensor unplugged. I replaced the sensor, but even still unplugging the sensor makes it run better. I also retested fuel pressure while the car is moving and it stays around 20 p.s.i. I see that W4rky says it should be closer to 40? Is that my problem right there? I need help making sense of this I seriously appreciate any help as I am trying to get this car running well enough for my little brother to drive daily when I ship out for the air force on the 16th. Thanks!

[WmWatt]

Did you check the fuel filtre and line? Someone may have run over something and damaged the fuel line. Is the fuel tank clean or is there something clogging the fuel intake? Is there a vacuum build up in the line? How about the fuel filller cap?

[ryanprins13]

I have never tested fuel pressure myself but i believe it should always be 40-44psi. Most festiva people are at a meet this weekend, lol. Will knows more about the fuel pressure. It could possibly be the fuel pressure regulator? But that is just a guess of mine, maybe not. If i get a minute i may look in my manual about fuel pressure. Maybe a bad wire going to the pump? How is the new transmission?

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[ryanprins13]

A

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[anthony1707]

So the fuel filter is actually a new one, and the line appears to be intact, and I can suck gas out from the tank using just my mouth so I assumed that if it was clogged it would not be so easy to suck gas out. 36.3 p.s.i is what that manual says, and I am only reading about 20 so I suppose that is the issue. The fuel filler cap seems okay, and the fuel tank is pretty clean but I will inspect it further to make sure the fuel sending unit has clean connections, and I had not considered a vacuum pocket in the fuel line. What else could cause low fuel pressure like that? Anything I can test? Ryanprins, I actually just came back from the junkyard this morning with a fuel pressure regulator, an Idle air control valve, and throttle position sensor (they had a sale so I figured I would go ahead and get what I might of needed) that I will be installing today to see if anything changes. I am very happy with the new transmission! My previous 5-speed would grind 2nd gear 100% of the time, so I am very pleased with the new one that shifts through all gears perfectly, and feels great with the new clutch. I also thought I should mention that at that L K Q in chula vista california, there are two other festivas that still have their b3's and 5 speed transmissions. One carbed, and one EFI. The carbed has around 90k miles.

[Sid_RallyX_82]

It seems like you guys have this covered, but just a thought, check that you have full voltage at the pump and 0 voltage coming out while it's running. If you don't have full voltage going in or have "left over" voltage coming out (very lengthy to explain) then the pump won't run at full capacity, no matter how new it is.

Yeah, in California, pretty much everyone will have their stock engines because of C.A.R.B. ... The only ones who don't are the one who are being sneaky with a b6 and they won't tell you it's a b6 because that's a quick ticket to getting your car crushed

[anthony1707]

Right sid, that is why I decided to just get a replacement B3, with the limited time I have I did not want to deal with getting it inspected and approved. Today I tested for voltage going to the fuel pump, and while there was no "left over" voltage, the electrical connector would provide 12v for maybe 2 seconds, and then would drop down to about 4 volts and then would rapidly fluctuate from 4-6v. I decided to just tap into the ignition 12v power source, so I now have a constant 12v power source, which did seem to make the car run better. However It will still buckle sometimes, even to the point where it makes the whole car shake violently. Testing for fuel pressure at the rail yielded 20 p.s.i, which is still too low. I then thought I would eliminate the possibility of the fuel line or the filter being clogged by running the fuel pressure test by slicing into the feed line coming directly from the fuel pump and this still yeilds 20 p.s.i! This tells me that something in that assembly is malfunctioning, and the filter looks okay. A brand new pump I had in before made the car run terrible with 10 pounds of fuel pressure and the old pump does not provide the full 38-40 pounds either. What am I missing here?

[tooldude]

Try gradually pinching off the fuel return line from the Fuel Pressure Regulator. If you can get fuel pressure to the proper rating, the FP Regulator is bad. If not, the pump is not making proper pressure. This could be caused by: (1) the tapped voltage source is system voltage but cannot supply proper current, (2) the piece of connecting hose on the fuel pump is leaking pressure, (3) the fuel pump does not meet required specs/is the wrong application, (4) the fuel pump ground is bad either through the inertia switch or at ground G400 below the liftgate center latch, (5) the fuel pump strainer is clogged, (6) there is enough restriction on the supply side that it's a problem for a higher flow rate.

[anthony1707]

Thanks for the advice tooldude, I actually tried pinching the return line from the PR and the pressure did not rise at all. I am also getting the same pressure reading at the pump as I am at the rail, so I am thinking between the pump and rail must not be clogged or restricted. I honestly did not think about possibly having improper current, and I will ensure the grounds are good, and I'll take another look at the pump assembly as see if anything is clogged down there.

[ryanprins13]

So you replaced the original fuel pump with a new one, new one was bad so you put the original back in? Is the wrecker close enough that you can grab a fuel pump or 2 there? How full is your gas tank?
Someone once had the positive wire to the fuel pump get kinked or have some issue so when the car vibrated or went over bumps the fuel pump would cut in and out. They ran a new power wire which fixed it. You did that and while using too small wires would give you less than 14 volts it should run steady and not change while your driving. That makes me think its quite possibly a bad ground.

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[anthony1707]

Ryanprins13 that is exactly right, the new one was faulty. So today I did more testing and I found that the fuel pump is good. I ran it in a bucket of cleaning solvent with 12v straight from the battery and it would run. When the return line on that little rig was crimped, the pump would build close to 60 p.s.i. This led me to think that for some reason the fuel going throughout the car was not meeting proper resistance. For some reason when I unplug the vacuum line that connects the fuel pressure regulator to the intake manifold, the pressure jumps to 38 p.s.i at idle as it should. plugging it back in will cause pressure to drop back to 20-25. I drove it today with the nipple coming from the intake manifold plugged, and with the hose to the pressure regulator disconnected and it ran like a top! looking at the fuel pressure while driving, it does go down to about 30, but it drives really well especially compared to how it ran before. Does this mean that the fuel pressure regulator is faulty? also, should fuel pressure stay at a constant 38 p.s.i when driving?

[tooldude]

Not trying to answer for someone else or break any etiquette I don't know about - the specs for the FPR are: 39psi@0in.Hg. - 33psi@10Hg - 30psi@15Hg - 28psi@20in.Hg. Fuel Pressure Leakdown test for the FPR: Run engine 30 seconds minimum. Fuel pressure should drop no more than 5psi for 60 seconds. [The fuel pump check valve leakage allowed is 2 psi max for 3 minutes] FPR valve seat leakdown test: Apply 20 in.Hg. Vacuum should not drop more than 10 in.Hg after 10 seconds. OEM fuel pump outlet pressure: 64-85 psi (max) - operating pressure 28-40.5 psi.

[Sid_RallyX_82]

Ryanprins13 that is exactly right, the new one was faulty. So today I did more testing and I found that the fuel pump is good. I ran it in a bucket of cleaning solvent with 12v straight from the battery and it would run. When the return line on that little rig was crimped, the pump would build close to 60 p.s.i. This led me to think that for some reason the fuel going throughout the car was not meeting proper resistance. For some reason when I unplug the vacuum line that connects the fuel pressure regulator to the intake manifold, the pressure jumps to 38 p.s.i at idle as it should. plugging it back in will cause pressure to drop back to 20-25. I drove it today with the nipple coming from the intake manifold plugged, and with the hose to the pressure regulator disconnected and it ran like a top! looking at the fuel pressure while driving, it does go down to about 30, but it drives really well especially compared to how it ran before. Does this mean that the fuel pressure regulator is faulty? also, should fuel pressure stay at a constant 38 p.s.i when driving?

Not trying to answer for someone else or break any etiquette I don't know about - the specs for the FPR are: 39psi@0in.Hg. - 33psi@10Hg - 30psi@15Hg - 28psi@20in.Hg. Fuel Pressure Leakdown test for the FPR: Run engine 30 seconds minimum. Fuel pressure should drop no more than 5psi for 60 seconds. [The fuel pump check valve leakage allowed is 2 psi max for 3 minutes] FPR valve seat leakdown test: Apply 20 in.Hg. Vacuum should not drop more than 10 in.Hg after 10 seconds. OEM fuel pump outlet pressure: 64-85 psi (max) - operating pressure 28-40.5 psi.

If you're getting the right fuel pressures at Bar and idle vacc., then maybe were barking up the wrong tree...
So let's back up. Old motor ran like crap. New motor runs like crap. Fuel pressure is good. What else have you kept from the old engine and are still using?

[bravekozak]

Make sure there is no fuel/water separation in fuel tank.
Blow out fuel line with compressed air.
Change Denso fuel pickup sock.
Report back.

[4_whl_hvn]

I know it has been a while since you have posted, but did you ever figure out what was causing your problem? I have been chasing similar symptoms and I suspect my fuel pressure regulator but don't want to just 'throw' parts at it.