I just replaced my stock fuel pump with a Walbro high pressure in tank pump. Before my car was running between 36-40 psi fuel pressure. Well, since I made the swap, it never gets above 18-20 psi and when I nail it from idle it has a bad hickup...I'm assuming that it does this b/c of the low fuel pressure. I don't know if there is a line pinched or what. I have checked what I could without dropping the tank again and there are no leaks or pinches that I could see. After it finally cranks it idles fine, just has no fuel pressure. Anyone ever run into this before????

 

Anyone got any ideas????

 

I could be VERY wrong with this, but from what I hear the Walbro pump is not a direct drop in pump, you have to mod the bucket to make it sit up right and I BELIVE you have to mod some wires. but that was for my racetronix setup. If you KNOW your install was correct, perhaps change your fuel filter? Who knows what you stired up in the tank when you did the pump

 

Well, I didn't have to mod the bucket...or at least I didn't do that b/c it seem to sit up just fine. But I did have to cut the factory plug off and butt connect the plug that came with the pump to the original wires because the plug was different than stock. That was my first concern because that butt connection is inside the tank and I didn't really like that. As far as the bucket though, I didn't see a reason to have to modify it. And as for the fuel filter...I installed a new one during the fuel pump install. You can hear the pump come on just like it is supposed to. I have tried cycling the key on and off to try and build up pressure but it still never gets above 20 psi. Even when I stab it and the rpms go up to about 4-5 grand....it never goes above 20 psi...Thanks for the suggestion. As bad as I hate to do it, I guess I will have to drop the tank again and make sure nothing happened to the pump in the re-installation process.

 

Well the pump fits into the stock bucket but its not at a perfect upright angle. My buddy and I had to shave the ridges at the bottom of the bucket where the pump sits, know what i mean? Its the SAME exact pump you put in, so I wonder how you did it without shaving those ridges off the bottom of the bucket.

 

yeah I remeber the ridges...but I thought that it was in there good. Okay, that may be the problem. I bet the pump was not in there as good as I thought and now it has worked its way loose inside the case. Did you also have to cut the factory plug off and use the one sent with the pump? Thanks...even if I have to drop the tank again it will be okay as long as the pump is okay..Also my buddy suggested that the fuel line and the return lines may be hooked up backwards, is it possible that the car would even crank or run with these reversed???

 

Another question...what is the brown bucket for? Is that just for noise reduction or something? Do I need it really? I saw some pics of an install where the guy just hose clamped the new pump to the bracket and didn't even use the bucket. Also I noticed that he used a new piece of fuel line instead of the brown colored flex hose that was on the old pump. He also had a plug assembly for the new plug, where as I just butt connected the new plug to the stock wires. Are any of these set in stone as to which way you do it or is it pretty much whatever gets the job done?

 

dont know if it helps or not but when i did mine i just put the suction end of the pump into the little hole at bottem of the metal bracket, and zip tied pump to the metal shaft so to speak,,
i have not checked fuel presure yet,,, but it runs great,

 

well racetronix setup has a new harness so yea, my buddy re-did the wiring for me. CHeck out how the pump is sitting in bucket, i bet ya its lob sided

 

The LT1 F-body cars have a pump that is inside a plastic bucket. This bucket in combination with the fuel pump in it is designed to draw fuel from the bottom of the tank via suction. This keeps the bucket full at all times so that when the tank is low on gas and you are doing some hard cornering or acceleration the pump does not run dry and start aerating the fuel. This happens as the fuel sloshes from side to side in the tank leaving the center low on fuel. This can cause detonation and possible engine damage. The bucket also allows the car to operate with lower fuel levels in the tank due to its scavenging effect. The bucket can also effect motor cranking time as the priming time is reduced under certain conditions. The return line from the fuel pressure regulator is diverted back into the bucket via a filter sock inside so that the unused fuel also helps keep the bucket full at all times. Keeping the pump constantly immersed in gas within the bucket can extend the pump’s life by not allowing it to be exposed to open air. Open air within the tank contains moisture and in time will cause the pump to rust / seize up especially if left to sit for long periods of time without the tank topped-up (i.e. winter storage). The Racetronix pump assembly is modified with an o-ring so that it will properly seal in the bucket’s rubber check-valve so that its function is retained. The Racetronix pump assembly is fitted with a factory style fuel tube not a rubber hose. This hose is important as when the fuel module is placed back in the tank it must pivot which can cause the rubber hose to kink. This fuel tube is much more resistant to the solvents in today’s gas and it will not crack, split, swell and collapse like a rubber hose. The standard Walbro kit comes with a short length of 50PSIA rated rubber hose. The Racetronix fuel module is equipped with a one-piece soldered wiring harness made from mil spec. Teflon/silver wire. This is the same type of wire used at the factory as Teflon is the most resistant to deterioration when exposed to gas. This harness has a Walbro connector at one end and GM pins at the other which fit directly inside the factory connector. Due to the age of the F-LT1 cars much of the in-tank connectors are black / corroded due to age. The Racetronix harness replaces all these questionable components. The standard Walbro kit comes with a plastic coated in-line wiring adapter. This adapter must plug into the existing questionable factory in-tank wiring thereby adding additional connections and length.

If the bucket’s function or any of the other kit’s features are not important to you then a standard GSS307 or GSS340 255L/Hr pump can be retrofit onto the F-LT1 module. The Racetronix kit is not required to get an F-LT1 system running but rather as a better option in order to retain factory functionality, maximize pump performance and reliability.

Jack
Racetronix

 

Thanks for all of the help. The kit I got from New Era performance did not come with any of that. It came with the pump, 2 hose clamps, and a new wires with a plug on one end and open wires on the other. It didn't come with a new hose, plug to pin wires or any of that. I will drop the tank again as I am thinking that the pump is not seated properly in the bucket and/or the hose may be kinked b/c it seemed pretty flimsy to me. I will tackle this project next weekend. Dropping the tank once a weekend is plenty for me. I will repost with the solution once I figure it out. Thanks again to everyone for their suggestions, they were all very helpful.

 

Well, I just couldn't stand it so I went ahead and dropped the tank again this evening. There are two hoses that connect to the bucket other than the fuel line that connects to the pump. One of them is a return and the other is like a vent hose or something. Well, I had these two backwards. I downloaded a copy of a pic that showed which hose was the return and which was the vent. Once I connected these to their proper place, I re-installed the tank, hooked everything up, cranked the car, and just like that I had my throttle response back and 38-40 psi. Oh yeah I did have to modify the bucket for the pump to sit straight up. Thanks to everyone that gave me some suggestions, I used them all.

 

No worries bro, glad it all worked out for you. Is your fuel gauge working ok?

 

Seems to be okay...I haven't filled it up yet, but it looks to be working okay. Thanks again.