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Walboro Fuel pump losing pressure

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DSM Wiseman
Dec 20, 2002
New Cumberland, Pennsylvania
I have a question for all of you guys running a 190lph Walboro FP.

After my car is shut off it seems as if the pump is not holding the fuel pressure in the lines. It requires significantly longer for the car to start and is very annoying. Is this normal for the Walboro pumps or is mine defective?

On my 255, it seems that the pressure is only temporary in mine as well. It'll start up almost instantly a couple hours after leaving it sit, but after that it may take some cranking. It takes about 3 seconds of cranking to start it in the morning.
Also it's "losing". Loose is the opposite of tight.
you might want to finish rewiring that and see if that helps. it might not be getting enough current at start up and takes it a little longer to get going.
like i said before, please try and re wire it and see if that helps. 99% chance it will help a lot.
This happened to a buddy of mine, when all of you switched out the fuel pump how much did you twist and turn the rubber fuel line below the tank? Even if you used the fuel lines on top of the tank, you have to twist the rubber line some to get everything apart. Everybody check this rubber line for a small leak, or just go ahead and replace it. :thumb:

It should lose alittle pressure but not all of it, and not in an hour.
It has something to do with the FP solenoid being unhooked. On the stock set up manifold pressure goes through the solenoid then into the FPR. On an aftermarket FPR setup you most likely hooked the vacuum line directly from the manifold to the regulator.
I always lose pressure too Im almost positive it just bleeds off though the fpr after the car is shut down. However I don't have restart problems.
Yes I also have no restart problems and no leaks what so ever. I have a full -6 line from the tank to the fuel filter right on through to the FPR leaks.
hellotbone said:
I always loose pressure too Im almost positive it just bleeds off though the fpr after the car is shut down. However I don't have restart problems.

I don't either. I have a 255HP(not rewired), Old style spoolinup 1gAFPR on a 1g rail, and my FPS still hooked up.
my car did this for awhile. had no pressure after shutting car off. took like 4 or 5 secs of cranking before it would start.

but also, car would nto boost because we could not set the base fp high enough. i thougth maybe the fpr (brand new) or fuel pump was going out. so i bought a fuel pump, went to replace it and found out whoever i got the pump i had from used regular fuel line between the pump and sending unit instead of high pressure line.

well, there was a rip the length of the fuel line and so fuel was just dumping back out into the tank and not getting to the engine. so, replaced the pump anyway just ebcause i had a new one and it is the hp version instead of the regular version... so sucks that i spent money on a new pump when i didnt need it and a simple $1 high pressure fuel line( i got a discoutn) was all it took to fix it.
Holy crap you guys are fast with the replies.

I guess I should clairfy my original post. I can't verify that it is losing pressure, as I don't have a FP gauge. Sorry for the mixup.

It just takes significantly longer, maybe 5 or 6 seconds to start if the car sits more than an hour. It used to start in 3 or 4 cranks.

I didn't install the pump so I don't know how they did the installation. Could you be more specific as to what I should look for?

The car also seems to sputter after startup for about 30 seconds almost like there is air in the lines. :confused:

Thanks again for the lightning fast replies!
I don't know about 2Gs but for 1Gs, there is a fuel pump check valve right next the battery on the firewall that you can jump to the positive terminal which will power up the pump without starting the engine so you can check all fuel lines and connectors for leaks. If everything checks out, the o-ring at the tip of the pump is probably worn out or it was never install correctly. On a side note, you should get a afpr to keep that 255 from overrunning your stock fpr. Good luck.
I went with the 190lph so I wouldn't have to worry about an AFPR. Provided that my information was correct about only needing it with a 255 & 255HP.

I will look on alldata tonight and see if I can find anything out about the check valve. If not I guess I will have to pull the pump.

I don't think taking longer to start will hurt anything, but it's really annoying. :(
if your problem is consistant, you may have an issue with the o ring that goes in your fuel pump assembly. if you reused the old o ring, or tore the new one/didn't seat it properly, then you will lose pressure that way. not while driving, but after the engine is off.
if you didn't lubricate the o ring before you put it on there is a good chance you tore it. check the vfaq's for the walbro install and you'll see what i'm talking about.
I have the 255HP and don't have a problem with starting now. When I turn the car off it drops to about 23 psi then will slowly go to 0 (I think or slightly above haven't paid much attention) after a few hours, but 98% of the time it starts like normal, the other times it may take an extra second. Make sure you check the oring on the fuel pump outlet that seals against the sendor assembly. This is a common place for a leak & is easy to install the oring slightly croked since the walbro outlet shaft is slightly longer then the sock so the oring can move back & forth. Mine origionally had a problem with longer then normal starts until I reinstalled this oring.

This is what I did to get my oring as straight as possible. On the output shaft there is a spacer, oring & then a cap. Before I installed the pump I had everything put on the shaft and move the spacer up the shaft, moving the oring till it is just about touching the end cap. Now install the assembly, & once its in place slide the spacer, moving the oring up until you get to your mark, keeping the spacer as straight as you can. It seemed to be easier to get it straight this way compared to installing the whole assembly and trying to keep it straight while doing so.

EDIT SleeperG beat me too it :coy:
I just installed a 190 in my 2G. No rewire and no FPR. I have the same problem. What is weird about mine is that for the first few days after the install, the car would start abnormally quickly, like on the very first crank. Then, all it once, it had the same symptoms described above. Any thoughts on that?
Well thank god i found this post becuase i just did a 255 pump about half an hour ago and the same think happens to my car, it will need to crank for about 3-4 seconds before it starts, but i also believe that the pump i got isnt for my car, i had to do alot of modifying, also the exert on were you put the o-ring is pretty long and it just doesnt seem to make it the o-ring is in place but the other black tubaler bracket went in twisted it really retarded, but the seems fine i guess, i am going to get a gauge tomorow and see what happens
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