racerx520

iTrader: (1)

Hey guys, figured I'd make a new thread since I'm not sure if it's the same problem as before but I'm sure it probably is. I am having a problem with fuel AGAIN. I just replaced fuel pump, pulsator, sender, afpr and injectors and it was running great but I needed to adjust the afpr since it was running high psi. Well I finally moved the car from the garage to get to the Xmas decorations and the car hardly runs again. Put a fuel pressure Guage on and now it runs at almost 30 psi again, and once the car stalls and the fuel pump kicks off, instant 0 psi. Any thoughts? I can't get this fuel problem under control despite how many parts I throw at it.

mmadden55

Fuel filter?

racerx520

iTrader: (1)

I did a quick leak down test. Pinched the return line and when I turn on the key I hear the pump go on (walbro pump was told it's a but higher pressure) and it got up to 30psi. After the pump kicked off it was instant 0. The research I did real quick is fuel injectors. After I did the pump, filter, sender, pulsator and afpr I had it at about 55 psi with the vacuum line connected, so pretty high. I was really just to lazy and in a rush to get back to my newborn baby to sit at my friends shop and adjust the afpr. I road tested the car for a couple days (which included a few burnouts too and a few stomping the pedal to the floor) without adjusting the pressure cuz of laziness. Is there a chance maybe I blew up the 24lb southbay injectors I put in it? I have a set of 24lb svo injectors laying around here somewhere I could try but I don't want to tear down the intake system again before you guys read this and tell me maybe the problem is something simpler......I really really hope it's not the fuel pump leaking back. I'd be pissed since everyone gave walbro such good reviews.

Fred SS

iTrader: (3)

Congratulation on your newborn. I would suggest you remove the pulsator and replace with a length of fuel injection hose rated for immersion. I have heard that it is common for the pulsator to leak.

racerx520

iTrader: (1)

It isn't acting like a leak though. That was a problem last time I think where the pressure was flopping, now it is steady but low until stall. Sure hope it isn't the pulsator, it's brand new and I don't really have time until spring to do another tank drop

racerx520

iTrader: (1)

Thank you !

racerx520

iTrader: (1)

I think I need to redo the pressure test, I think I did it wrong for testing the supply line.

Fred SS

iTrader: (3)

I re-read your posts and your correct, it is not the pulsator. By pinching the return line and pressure still dropped to zero rules out anything in the tank.

racerx520

iTrader: (1)

The searching I was doing came up with says that if it leaks back without the supply line pinched then it can be the fuel pump....which I just replaced about a month ago and drove the car for like 3 days.

One of my biggest questions though is if high pressure (45-55 without the vacuum line disconnected) can ruin the afpr or Bosch injectors from southbay.

racerx520

iTrader: (1)

Ok, so I think I have bad news. Run the motor and clamp return line, then clamp supply and cut the motor real quick and holds pressure but won't hold with just return clamped. That's indicative of problems at the pump, right?

Fred SS

iTrader: (3)

I have an afpr. I've had my pressure up to 50 psi without issues. Since then I've reduced it to 45 psi after I saw higher HC readings at my last emissions test. Also, I saw a video from one of the injector companies, where they tested Bosch 3's up to about 60 psi and they still flow perfectly.

I think my previous post about pinching the return fuel line may be erroneous. If you pinch the supply line and the leak stops, then there is a problem in the tank. If you pinch the return line and the leak stops, then something is wrong with the regulator. If you pinch both and the leak continues then the injectors are leaking. Someone please correct me if I'm I'm wrong.

Fred SS

iTrader: (3)

Correct.

racerx520

iTrader: (1)

Ugh....I can't believe it. I have had nothing but problems with this car lately. It's like it just wants to go to the crusher. I'm so livid right now over this thing. The pump, sender, afpr, filter, pulsator and sock were all just replaced literally a month ago. And only drove maybe 5 days tops.

Fred SS

iTrader: (3)

Of all the new parts you installed, the pulsator is the weak link. Apparently it is a known leak path. When I did my swap, I did not install it. For now, leave the car alone for awhile, take a break.

racerx520

iTrader: (1)

I thought the pulsator is necessary in these cars. It's not acting like it was before. I think it's the check valve in the pump since it is leaking back. With the pulsator before it wouldn't hold pressure steady while running but when it shut down it still held.

Fred SS

iTrader: (3)

Strange problem. In my TPI swap, I did not use the pulsator. I also installed a new bosch fuel pump and sock. When the motor is running, fuel pressure stays steady. When I turn off the motor, the pressure slowly bleeds down to zero in about 5 minutes. Since the motor runs fine, I have not looked into it but I suspect the check valve in the pump is not functioning properly. In your situation, your pressure bleeds to zero immediately. From your previous tests, it would appear something is wrong in the tank, either the pulsator or the pump.

racerx520

iTrader: (1)

Hmm....maybe I'll have to look into running without the pulsator. I'm not going to go with walbro again. I think 5 mins is fine, i think in a perfect world the system is supposed to retain pressure slightly

Fred SS

iTrader: (3)

I'm a little surprised your having a problem with the walbro pump, but from your other thread it would appear knock-offs are in the mix. Man, it can be so hard and expensive to get good auto parts these days. Unless your buying from a known good source, don't buy. When I finally get around to changing pumps, I'm going with racetronix. You can buy directly from their website.


Good Luck.

racerx520

iTrader: (1)

i may go with them, just because ive heard a few things about them, and only good things.

Steve Mack

iTrader: (5)

Crank the afpr back up to 55 psi since it ran fine before at that pressure.It's the last thing you adjusted it could be the problem.

racerx520

iTrader: (1)

i never adjusted it from 55psi, i never had a chance to. the exact way the car was running i put it away that way, started it up a month later and super low psi, and pressure wont hold.

twinsemi

Can you disconnect the fuel lines from the tank, block them off and pressurize them? Look for any leaks, maybe an injector or two stuck open. Air pressure is going to be better than using the fuel pump to look for leaks.

racerx520

iTrader: (1)

If I leave both the return and supply clamped it holds pressure in the fuel rail. My only other thought would be the rubber lines from the sender to the hard lines under the car, but I don't smell or see any gas

twinsemi

So if the fuel rail holds psi with both ends blocked, then your injectors aren't leaking down. And I think you said earlier that you hold pressure if just the pump line is blocked off. It kind of has to be either the pulsator or the pump, since you have no external leaks. And when we point the finger there, we are first looking at any fittings that might be leaking inside the tank.
FWIW, I have had very good results with an Aeromotive 340 pump in my 55. It is connected to a PWM box that gives me adjustable delivery, since it has more capacity than my motor needs. I'm hoping it will last longer that way.

racerx520

iTrader: (1)

From whatI was reading a lot of people have problems with the check valves in the pumps but I guess it could be the pulsator too. Fred said he removed his pulsator, is that ok to do? I thought it was a necessary part

L98GTA87

iTrader: (1)

I removed my pulsator when I put in my racetronix pump. No problems with it.

racerx520

iTrader: (1)

Which racetronix pump did you buy? I saw 2 different ones. I may just remove the pulsator then since that's 2 people with no problems

L98GTA87

iTrader: (1)

I got the whole kit with the upgraded fuel pump harness but to be honest didn't really notice a difference with the harness. Here's the link:

http://www.racetronix.biz/customkiti...c=RFPK-005&eq=

Fred SS

iTrader: (3)

From what I have read, the pulsator is suppose to smooth out the pulses from the fuel pump. But that was over a decade ago. I think the latest design fuel pumps today, Bosch, Ractronix, etc probably don't need it. When you drop the tank to replace the pump, get rid of that pulsator. To replace the pulsator, be sure to use fuel injection hose rated for immersion. Regular fuel injection hose is intended to have constant contact with fuel inside the hose, but long term contact with fuel on the exterior surface will damage the hose. There is hose made specially for use in fuel tanks where the hose will be immersed in fuel. Go to a good auto parts store like NAPA. Good luck.

racerx520

iTrader: (1)

i'm sure that you're right, but i just want to make sure there are more success stories of no pulsator and no horror stories lol. i dont want to have to drop the tank again, its starting to turn into my 5x transmission swap cuz i kept buying 700r4's on craigslist lol

ULTM8Z

If you're clamping the return, it'll mask a problem with the AFPR. I once had a cheapo Accel regulator leak pressure, and then returned it to Jegs.

I then got a TPIS regulator and it doesn't leak.

My bet is the AFPR. What you should do is unhook the return line at the tank, then key on to energize the fuel pump. If it leaks significantly, your regulator is faulty.

racerx520

iTrader: (1)

But it holds pressure if I clamped the supply line too. That's why I think it's the pump. IIRC, if only return doesn't hold pressure then that's the reg. But this is the supply which isn't holding