Car struggles when I go WOT and loses fuel psi as I rev high
09-12-09, 10:21 PM
#1
Car struggles when I go WOT and loses fuel psi as I rev high
Hi,
I am trying to get the car running fine and all so I can sell it. The car is acting weird and I am not sure why. Here's a little background of what happened/happening.
I autocrossed it this one time... last run, the car just bogged and then it died on me. Not sure if it was because the gas was out... but the needle was not even close to E yet. There were no fuel psi at all, pinched the lines around... took awhile but it started to hold pressure. Car started up then head right home with a gas fill up. After that, I took the car out and see if anything is wrong... drove around and the car would struggle and sound weird and bog when I put more than 50% throttle. And as I rev, the car would struggle even more. So something gotta be wrong, I did that with the hood open... my bro realizes that the pressure drops.... from 2.5 down to 2 when I hit 7K RPM. Sometimes, the car would die and NO pressure AT ALL unless I pinch around on the lines. It's WEIRD! I thought maybe the tank had some rust in it and the pump picked it up. So now, I replaced both... the car still have the same struggle when I apply a little more throttle. It sounds like it's fine if I don't put too much throttle. Not sure why, and the pressure still drops as a I rev it up high. I use a 15A fuse for the pump, not sure if it has to do with anything.
What is the problem? I haven't checked the compression but I will try to get to that soon. Do I need a new carb? Is it the lines?
I am trying to get the car running fine and all so I can sell it. The car is acting weird and I am not sure why. Here's a little background of what happened/happening.
I autocrossed it this one time... last run, the car just bogged and then it died on me. Not sure if it was because the gas was out... but the needle was not even close to E yet. There were no fuel psi at all, pinched the lines around... took awhile but it started to hold pressure. Car started up then head right home with a gas fill up. After that, I took the car out and see if anything is wrong... drove around and the car would struggle and sound weird and bog when I put more than 50% throttle. And as I rev, the car would struggle even more. So something gotta be wrong, I did that with the hood open... my bro realizes that the pressure drops.... from 2.5 down to 2 when I hit 7K RPM. Sometimes, the car would die and NO pressure AT ALL unless I pinch around on the lines. It's WEIRD! I thought maybe the tank had some rust in it and the pump picked it up. So now, I replaced both... the car still have the same struggle when I apply a little more throttle. It sounds like it's fine if I don't put too much throttle. Not sure why, and the pressure still drops as a I rev it up high. I use a 15A fuse for the pump, not sure if it has to do with anything.
What is the problem? I haven't checked the compression but I will try to get to that soon. Do I need a new carb? Is it the lines?
09-12-09, 10:40 PM
#2
Definitely soundfs like fuel supply. Since you ran the tank low along with the hard cornering during autocross, I'd look at a clog in the intank pickup tube. I had one that would strart right up and idle fine, until I gave it the slightest bit of gas, then it immediately died. This was with a new pump and filter. Finally traced it down to a pickup tube that was clogged with rust.
I know it's a pita, but the best fix is drain/drop the tank. Pull the fuel pickup/return assembly, I bead blasted mine clean. then inspect the tank for rust and consider having it boiled and sealed. Many radiator shops can do the boiling, sealing can be done yourself. A qt. of sealer runs about 20 bucks and will do the entire tank, boilng can run 30-40.
Use PB Blaster and an impact screw driver to remove the screws on the pickup assembly. I replace them with allen head screws for easier removal later on.
I know it's a pita, but the best fix is drain/drop the tank. Pull the fuel pickup/return assembly, I bead blasted mine clean. then inspect the tank for rust and consider having it boiled and sealed. Many radiator shops can do the boiling, sealing can be done yourself. A qt. of sealer runs about 20 bucks and will do the entire tank, boilng can run 30-40.
Use PB Blaster and an impact screw driver to remove the screws on the pickup assembly. I replace them with allen head screws for easier removal later on.
09-13-09, 08:37 PM
#4
If you're pressure is dropping it has nothing to do with timing. Even if your timing was off, I'd start with the fuel problem first.
Where is the fuel pressure gauge mounted exactly..?
Is it a GSL-SE model...? The pick-ups in the tank are different btwn the GSL-SE and the lower models.
Edit: Sorry I just seen your signature. Being it's a GS the pickup tube is inside the tank and unlike the SE can't be removed to check. You could remove the feed line and drop a hose into a gas can to see if the same pressure drop is happening. See if you can blow back into the feed line on the tank.
I just had to go actually check a gastank I have laying around to see if what I wrote was true, that you couldn't remove the pickup on the lower models and I was right. That almost seems absurd. I removed the float for the gas gauge and looked in with a flashlight and sure enough the pickup tube does have the screen and a "S" shaped line just like I thought. The "S" shaped line on my SE tank was clogged on the part that runs parallel to the ground... But again, on the SE tank the pickup could be removed to fix it...?
Where is the fuel pressure gauge mounted exactly..?
Is it a GSL-SE model...? The pick-ups in the tank are different btwn the GSL-SE and the lower models.
Edit: Sorry I just seen your signature. Being it's a GS the pickup tube is inside the tank and unlike the SE can't be removed to check. You could remove the feed line and drop a hose into a gas can to see if the same pressure drop is happening. See if you can blow back into the feed line on the tank.
I just had to go actually check a gastank I have laying around to see if what I wrote was true, that you couldn't remove the pickup on the lower models and I was right. That almost seems absurd. I removed the float for the gas gauge and looked in with a flashlight and sure enough the pickup tube does have the screen and a "S" shaped line just like I thought. The "S" shaped line on my SE tank was clogged on the part that runs parallel to the ground... But again, on the SE tank the pickup could be removed to fix it...?
09-13-09, 10:28 PM
#7
I'm just thinking out loud.
Seems like a pain in the *** but dropping the tank and blowing into the pickup tube freely would rule out pickup tube being clogged.
While you had the tank down you could undo the gas guage float, look inside the tank & see the screen that covers the pickup tube to make sure she's clean / free of debris.
Disconnect at the regulator and then at the fuel filter or fuel pump, whichevers back there in line first and blow thru to see if it flows freely.
Get a multi meter and check the leads to the fuel pump when the pressure drop happens. See if maybe you're loosing voltage and the pump is not doing it's job 100%.
At least that's what I'd do.
Just keep ruling out the next possible cause until it's fixed.
Seems like a pain in the *** but dropping the tank and blowing into the pickup tube freely would rule out pickup tube being clogged.
While you had the tank down you could undo the gas guage float, look inside the tank & see the screen that covers the pickup tube to make sure she's clean / free of debris.
Disconnect at the regulator and then at the fuel filter or fuel pump, whichevers back there in line first and blow thru to see if it flows freely.
Get a multi meter and check the leads to the fuel pump when the pressure drop happens. See if maybe you're loosing voltage and the pump is not doing it's job 100%.
At least that's what I'd do.
Just keep ruling out the next possible cause until it's fixed.
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