Wades SnS

iTrader: (2)

Ok so let me start with a little history. 98 T/A cam only car, was tuned 4 years or so ago. Car sat for three years sold it and the guy who purchased it drove it for 3 weeks then calls saying it has lost power and wont rev. So conclusion is low fuel pressure when reved above lets say 3000rpms when accelerated at a fast rate. Bought a walbro 255, put it in same thing. even at a set still if it is reved above a certain rpm quickly( snap throttle) the fuel pressure drops to near nothing. Same scenario when driving, you can watch the fuel pressure go from around 56 to 5 in a matter of about 2sec. If you let out of it it will slowly climb back to normal. on to what has been tried, Two walbro pumps, two fuel filters, new hose between pump and pump assembly, new steel braided line between filter and rail, new injectors, and the hot and ground for the pump have both been hard wired to the battery, new regulator and even tried crimping the return line. At this point in time I am out of ideas, any ideas on what it could be or what else to change.

Wades SnS

iTrader: (2)

no one has any words of wisdom? I'm clueless at this time.

All-In

If it were mine I'd be looking closely at the FPR and it's associated vacuum line first.

white01ss

iTrader: (37)

No fuel leaks? Stock style fuel system?

If you're running the stock in tank FPR and associated lines, that stock FPR could be bad.

Where's the fuel pressure gauge plumbed into? Could there be a blockage in the fuel feed line?

Wades SnS

iTrader: (2)

no fuel leaks, no vacuum line to the regulator and, stock system just a walbro pinon and steel braided hose

All-In

white01ss is right, it's located inside the fuel tank. I came across this:



That's it being held in place by the silver colored clip.

gofastwclass

iTrader: (2)

All-In and white01ss, I thought 98's had the return line on the rail. If so the fuel pressure regulator is on the rail.

I do agree with you guys, it sounds like a fuel pressure regulator issue to me as well.

Wades SnS

iTrader: (2)

If the fpr is the item shown in the pic it has been replaced. If it is on the rail I am not sure what it is or isn't . The rail looks just like a 2000 model. As for the vacuum line going to the one in the tank I can not find any.

white01ss

iTrader: (37)

Stock FPRs are fixed at 58 psi so no vacuum line.

If the tank mounted stock FPR has been replaced (and tested?) I'd start looking for a crushed spot in the fuel feed line. A restriction in that line would be like having too small a line. Pressure would look fine until the engine starts using more than can be supplied. At that point the pressure at the rail would fall off sharply.

If you can, replace the entire line with a new one.

PAGregSS

iTrader: (10)

I bet it's leaking at the hose between the tank bulkhead and the pump, in the tank.