Walbro check valve sticking?

[392charger]

Hi guys. I'm brand new to this site and here's my question. Having trouble with the Walbro fuel pump in my mostly stock 1987 WE4. Pump only has less than a 100 miles on it and won't pump fuel unless I remove the check valve. This took dropping the tank MANY times to figure out. Car is a real pain to start since there's no fuel in the line at start up. Anybody have this type of problem and if so what was the fix other than a new pump. Walbro said they has issues with this pump and I gave them the number off the pump itself, to which they replied it was a newer pump and that the problem was corrected by the time mine was manufactured. Also said it has no warranty because I purchased over a year ago plus it's a high performance unit, so no help there. I was wondering if maybe the stock wiring harness was not supplying enough volts to the pump to bypass the check valve. How do you test the voltage to the pump? Is this pump junk? Do I need a Hot Wire kit? BTW, the number stamped on the pump is as follows:

F20000 169
O77207-1 Made in the USA
Pat 4500270 5421306

Thanks in advance for any help you can give.

[87geeinn]

Hmmm, not sure how removing the check valve actually helped you pump fuel. If the check valve is removed then if you do get the car to start, then fuel pressure will immediately drop off after you stop the car. I'm not sure if the check valve has any function when priming the lines/rail with fuel though.

I'd look elsewhere for your problem.

First, do you have a fuel pressure gauge? If not, get one. It's basically a necessity with these cars.

It's not much help if you can't "see" what's going on. Hell, you may even have a bad fuel pump relay. In that instance, the pump will prime, but only after the car has been cranked for a good bit and oil pressure comes up over 4psi. Then the oil pressure sender will send voltage to the fuel pump. It's basically a backup system incorporated into the oil pressure sending unit for when the fuel pump relay dies.

Could be a bad fuel pressure regulator, sticking injector, etc, etc. My advice: Get a fuel pressure gauge and stick it on the rail. And yes, you need a hotwire kit, but not until you figure this out BEFORE you start adding things to the equation. A hotwire kit just provides a stable 12v to the pump at all times, especially under load. However, a turbo regal should run just fine in stock configuration. That is: there's something wrong that needs fixin' before you add a hotwire kit.

Try this:

Go here (http://www.vortexbuicks-etc.com/), click "Troubleshooting" and then "Fuel Pump/Fuel Injector Circuitry"

[Keller]

First, where did you get the pump. There have been a rash of "Walbro copy" pumps from internet sources popping up on eBay, etc. The numbers are cloned, as well as the look and coloring of the pumps. Given the numbers, I have a feeling it was one of the TR vendors, however.

Secondly, what "check valve" are you removing? The one in the pump, or something external to it?

Third, have you ever changed the fuel filter?

A hot wire is always a good idea, as there are *7* wiring connectors between the alternator and the pump. The power strength weakens a bit with each one.

[392charger]

Thanks for the responses guys. Keller - I got the pump from G Body Parts and it seems to be a legit pump but how to tell for sure? The check valve I removed is in the pump itself. I swear it pumps but will not get pressure to the fuel rail unless the valve is removed. I've done this several times. It runs without the check valve but it 's a pain to start because the fuel drains right back into the tank at shut down. Bench testing help to confirm this problem, however that was done using power straight off a battery which is why I was supecting the factory wiring harness. Maybe it not getting enough voltage to the pump at start up. I don't know how to test the voltage output at the connector to the pump. Electrical is not my forte but I can figure it out if it's dumbed down enough for me. The fuel filter was changed even before I replaced the pump.

87geein - I'll check the fuel pressure agian, if I recall correctly it was about 33 lbs(static). I replaced the fuel pump relay with no change. Pressure regulator too but it was just Auto Zone brand. I really like those links you gave me though. I printed them out and will use them to further diagnose the problem. I'll keep you guys posted.

[87geeinn]

If you purchased the pump from G Bodyparts, you can rest assured you have a good pump, although it's always a possibility to have a lemon I suppose.

See the little black spade connector near the alternator? It should be right next to another green spade connector. The black one is the fuel pump test connector. Run a jumper wire from the black spade connector to the stud on the back of the alternator. The pump should run if the wiring back to the pump is intact. Does it?

With a paper clip, you can remove the schrader valve from the fuel rail and run a piece of hose to a container from the rail and run the pump to see if it is flowing. It should be a nice steady stream. Not exactly a perfect test by any means, but that should at least tell you if the wiring to the pump is intact.

When you replaced the pump, did you reuse the pulsator thingy? Did you make sure the hose was clamped tightly on the hanger?

I'm not sure which wire you have to backprobe to test voltage, but it's one of the three wires that can be accessed right under the driver's side rear bumper at the weatherpack connector. Of course, even if you have good voltage there, you could still have a problem from that connector to the pump itself. Maybe you pinched one of the wires after removing and replacing the tank numerous times?

[87geeinn]

Also see attached pic. You can pinch off the feed and return lines at the "soft" connectors down by the power steering pump.

[Keller]

With a paper clip, you can remove the schrader valve from the fuel rail <snip>
Mmmm...I would recommend using a real valve tool to do this. If a good auto parts store does not have one available, try a bicycle shop.

I'm still a bit surprised that you've been able to take this part of the pump apart without damaging the pump to a point of complete destruction. They aren't really meant to be taken apart. I just took apart an old AC one in the trash pile and it it was a little like opening a sardine can.

[87geeinn]

I'm still a bit surprised that you've been able to take this part of the pump apart without damaging the pump to a point of complete destruction. They aren't really meant to be taken apart. I just took apart an old AC one in the trash pile and it it was a little like opening a sardine can.

Very true. I'm going off of memory here, but I don't recall a way to actually take the Walbro pumps apart, much less put them back together.

Mmmm...I would recommend using a real valve tool to do this. If a good auto parts store does not have one available, try a bicycle shop.

I did actually pick one up, but you'd be amazed at how inventive you can be in a pinch or when you're stuck at the house and can't make a trip to the parts store. :)

[392charger]

Thanks for the help guys. Regarding the check valve or what I think is a check valve (please feel free to correct me if I'm wrong) IIRC, it's located in the outlet at the top of the fuel pump and is just held in via a crimped on bell shaped collar. I just pried a little bit and it came right off and under that is a plastic spring loaded needle and seat type lookinng thing that I assume is a anti drain back (check) valve? When the problem first started I bench tested the pump with the check valve in place, pump was running but no fuel came out. Thru the process of elimination I eventually removed the check valve and fuel shot out like a cannon (the small fire that resulted during this time from using jumper wires, from a battery to the pump, could have ended up very badly. That was really stupid on my part amd I won't do that again!), put it back in the car that way and it worked. After getting tired of hard starts with no check valve in place, I messed around with the check valve checking for burrs and what not and ended up re installing it in the pump, bench tested it again and it worked. So I put the tank back in the car, went to start it and... no fuel to the rail! I can hear the pump pressurize for a few seconds when the key is turned on too. After getting pissed, throwing some tools around and yelling at the dog. I dropped the tank again, removed the check valve, re installed the pump/tank, went to start it and... now has fuel and starts up. This takes several seconds of cranking though and I know that's not right because I have owned this car since brand new. Currently the tank is out of the car. Where do you guys suggest I start looking first?

[87geeinn]

If I were in your shoes, I'd get a new pump, get a fuel pressure gauge and install it...especially since the tank is down again.

Make sure you install it correctly. If you have the same problem, it's not the pump. I just can't help but think you've buggered the pump up by now.

Then, turn the key on and see if you have pressure to the rail. With a new pump and dry lines, it will take a few key on/off cycles to pressurize the now completely empty lines.

If no pressure, follow the troubleshooting tree that I posted.

Are you sure you installed the fuel filter the correct direction?

[Keller]

It would not hurt to ask your pump source if they would stand behind it.

The spring, etc., at the top of the pump also controls the pump output when there is higher flow needed. (i.e. under boost) With that not present, it might not be able to increase flow as needed under boost. Its absence is bad. Very Bad. That would be a recipe for blowing your head gaskets, burning a hole in a piston, etc. Some sources (e.g. Red Armstrong) shim this spring to raise the output of these pumps.

If the filter is installed properly, the regulator is OK (I recommend a -237 or adjustablle one), etc., then a new pump would probably be best. Either a replacement Walbro, or some have had good luck with Denso pumps for the last generation Turbo Supras. They are not at all plug and play, a very tight fit, and a wee bit expensive. They do offer higher output, however. On par with the requirements of a 550+ HP setup.

[392charger]

Update. Bench tested the Walbro pump again last night. Connected a brand new pressure gauge straight to the pump outlet and got reading of 32 lbs. w/o check valve in place. Installed the check valve and got NO fuel flow or pressure at all. Did the exact same test on another pump I had laying around (Borg Warner I think) and got a reading of 80 lbs! Is this ok? I guess that Walbro pump was junk. BTW, G-Body Parts was no help on this issue. This is a shame because I have purchased several things from them in the past. Anyway, I'll put the tank back in the car tonight with the 80 lb. pump and see how it goes and keep you guys posted.

[kenmosher]

If you bought it at FullThrottle, they have an exchange program that ends in April. You can get the pump diagnosed and exchanged if it's bad.

Basically, you've proven it's bad, so I'd get it replaced ASAP.

[392charger]

Here's an update for you guys. Installed a new pump and problem is solved. That Walbro was a POS. Guess I got screwed on that one but at least it's running good now. Sometimes it's the least thing you suspect ):0
Thanks for all the help though. It's very appreciated.